[{"Name":"Periodic law","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Periodic Law","Duration":"5m 19s","ChapterTopicVideoID":20260,"CourseChapterTopicPlaylistID":90859,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:01.590","Text":"In the previous videos,"},{"Start":"00:01.590 ","End":"00:03.630","Text":"we talked about the periodic table."},{"Start":"00:03.630 ","End":"00:07.560","Text":"In this video, we\u0027ll talk about the basis of the periodic table."},{"Start":"00:07.560 ","End":"00:11.820","Text":"The basis of the periodic table is the periodic law."},{"Start":"00:11.820 ","End":"00:19.545","Text":"In 1869, Dmitri Mendeleev and Lothar Meyer independently proposed the periodic law."},{"Start":"00:19.545 ","End":"00:24.615","Text":"They said that when the elements are arranged in order of increasing atomic mass,"},{"Start":"00:24.615 ","End":"00:27.225","Text":"nowadays we know it\u0027s the atomic number,"},{"Start":"00:27.225 ","End":"00:30.645","Text":"certain properties recur periodically."},{"Start":"00:30.645 ","End":"00:36.565","Text":"This was a revolutionary discovery and it changed chemistry completely."},{"Start":"00:36.565 ","End":"00:39.395","Text":"Meyer defined the atomic volume."},{"Start":"00:39.395 ","End":"00:44.495","Text":"He defined it as the molar mass divided by the density of the solid element."},{"Start":"00:44.495 ","End":"00:48.560","Text":"V the molar volume is equal to the molar mass,"},{"Start":"00:48.560 ","End":"00:51.110","Text":"which has units of grams per mole,"},{"Start":"00:51.110 ","End":"00:54.440","Text":"divided by the density of the solid element,"},{"Start":"00:54.440 ","End":"00:57.905","Text":"which has units of grams per centimeters cubed."},{"Start":"00:57.905 ","End":"01:04.235","Text":"Grams cancels, and we\u0027re left with centimeter cubed per mole."},{"Start":"01:04.235 ","End":"01:10.480","Text":"When the molar volume is plotted against the atomic mass or atomic number nowadays,"},{"Start":"01:10.480 ","End":"01:13.250","Text":"there are peaks for the alkali metals,"},{"Start":"01:13.250 ","End":"01:17.675","Text":"and he called this Group 1 all the alkali metals in Group 1."},{"Start":"01:17.675 ","End":"01:20.310","Text":"Let\u0027s try to draw it."},{"Start":"01:22.310 ","End":"01:26.600","Text":"On the y-axis, we have the molar volume,"},{"Start":"01:26.600 ","End":"01:31.700","Text":"and on the x-axis we have Z, the atomic number."},{"Start":"01:31.700 ","End":"01:35.315","Text":"When we plot the volume against the atomic number,"},{"Start":"01:35.315 ","End":"01:38.510","Text":"we see that there are peaks at lithium,"},{"Start":"01:38.510 ","End":"01:42.055","Text":"sodium, potassium,"},{"Start":"01:42.055 ","End":"01:45.330","Text":"rubidium, and cesium."},{"Start":"01:45.330 ","End":"01:48.390","Text":"This is lithium, sodium,"},{"Start":"01:48.390 ","End":"01:53.235","Text":"potassium, rubidium, and cesium."},{"Start":"01:53.235 ","End":"02:01.730","Text":"So we can see that the volume has peaks at the alkali metals,"},{"Start":"02:01.730 ","End":"02:07.175","Text":"which means that the alkali metals have a particular property in common."},{"Start":"02:07.175 ","End":"02:11.780","Text":"Now Mendeleev produced his periodic table in 1869,"},{"Start":"02:11.780 ","End":"02:16.025","Text":"and it was very significant and much"},{"Start":"02:16.025 ","End":"02:23.375","Text":"celebrated to the extent that now 150 years or so after its discovery,"},{"Start":"02:23.375 ","End":"02:30.200","Text":"it has been the basis of many articles and journals and films and so on."},{"Start":"02:30.200 ","End":"02:35.300","Text":"Mendeleev\u0027s periodic table had a different structure than the modern periodic table,"},{"Start":"02:35.300 ","End":"02:39.290","Text":"it had 8 columns which are called groups, and 12 rows,"},{"Start":"02:39.290 ","End":"02:42.610","Text":"and elements with similar properties are in the same group,"},{"Start":"02:42.610 ","End":"02:44.270","Text":"that\u0027s the most important thing."},{"Start":"02:44.270 ","End":"02:47.795","Text":"Elements with similar properties are in the same group."},{"Start":"02:47.795 ","End":"02:50.340","Text":"Let\u0027s take an example, Group 1."},{"Start":"02:50.340 ","End":"02:54.200","Text":"Group 1 contains the alkali metals whose properties are"},{"Start":"02:54.200 ","End":"02:59.795","Text":"similar and change gradually with increasing atomic mass or atomic number."},{"Start":"02:59.795 ","End":"03:02.160","Text":"For example, the melting point."},{"Start":"03:02.160 ","End":"03:06.290","Text":"The melting point of lithium is 174 degrees Celsius,"},{"Start":"03:06.290 ","End":"03:10.040","Text":"which is greater than that of sodium, which is 97.8,"},{"Start":"03:10.040 ","End":"03:13.505","Text":"which is greater than that of potassium, 63.7,"},{"Start":"03:13.505 ","End":"03:16.160","Text":"which is greater than rubidium 38.9,"},{"Start":"03:16.160 ","End":"03:19.475","Text":"which is greater than cesium, 28.5."},{"Start":"03:19.475 ","End":"03:25.070","Text":"So we see the melting point changes as we proceed down the group."},{"Start":"03:25.070 ","End":"03:29.245","Text":"Now Mendeleev noticed that there were some elements that were missing,"},{"Start":"03:29.245 ","End":"03:32.850","Text":"and he left spaces for 3 elements which were later discovered,"},{"Start":"03:32.850 ","End":"03:38.045","Text":"gallium in 1875, scandium in 1879,"},{"Start":"03:38.045 ","End":"03:40.940","Text":"and germanium in 1886."},{"Start":"03:40.940 ","End":"03:43.565","Text":"Let us take an example of germanium."},{"Start":"03:43.565 ","End":"03:46.660","Text":"Mendeleev called it eka-silicon,"},{"Start":"03:46.660 ","End":"03:48.840","Text":"which means after silicon."},{"Start":"03:48.840 ","End":"03:52.605","Text":"It\u0027s lower than silicon in the periodic table."},{"Start":"03:52.605 ","End":"04:01.130","Text":"We have silicon and below that we have germanium in column 14, group 14."},{"Start":"04:01.130 ","End":"04:04.710","Text":"Mendeleev proposed eka-silicon should have"},{"Start":"04:04.710 ","End":"04:10.745","Text":"the following properties: Its molar mass in grams per mole should be 72."},{"Start":"04:10.745 ","End":"04:19.550","Text":"Germanium has 72.6, it\u0027s density in grams per centimeter cubed should be 5.5,"},{"Start":"04:19.550 ","End":"04:24.635","Text":"in fact it\u0027s 5.47 and its color should be dirty gray."},{"Start":"04:24.635 ","End":"04:26.570","Text":"In fact it\u0027s grayish white,"},{"Start":"04:26.570 ","End":"04:29.195","Text":"which is not much different."},{"Start":"04:29.195 ","End":"04:32.510","Text":"Mendeleev realized that some elements"},{"Start":"04:32.510 ","End":"04:35.525","Text":"weren\u0027t in the correct place according to their properties."},{"Start":"04:35.525 ","End":"04:39.400","Text":"Even improvements in measuring the molar masses didn\u0027t help."},{"Start":"04:39.400 ","End":"04:44.150","Text":"This dilemma was resolved by Moseley in 1913."},{"Start":"04:44.150 ","End":"04:46.745","Text":"He measured the X-ray spectra."},{"Start":"04:46.745 ","End":"04:49.230","Text":"Using X-ray spectra of the elements,"},{"Start":"04:49.230 ","End":"04:51.170","Text":"Moseley measured the nuclear charge,"},{"Start":"04:51.170 ","End":"04:52.610","Text":"that\u0027s the atomic number,"},{"Start":"04:52.610 ","End":"04:56.705","Text":"and realized that the periodic table should be based on the atomic number."},{"Start":"04:56.705 ","End":"04:59.775","Text":"He predicted the existence of technetium,"},{"Start":"04:59.775 ","End":"05:02.080","Text":"which is Z=43,"},{"Start":"05:02.080 ","End":"05:04.660","Text":"promethium, Z=61,"},{"Start":"05:04.660 ","End":"05:07.230","Text":"and rhenium, Z=75,"},{"Start":"05:07.230 ","End":"05:11.705","Text":"and all these 3 were later discovered in 1937,"},{"Start":"05:11.705 ","End":"05:14.785","Text":"1945, and 1925."},{"Start":"05:14.785 ","End":"05:19.860","Text":"In this video, we talked about the periodic law."}],"ID":21053}],"Thumbnail":null,"ID":90859},{"Name":"Metals and Nonmetals and their Ions","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Metals and their Ions","Duration":"7m 44s","ChapterTopicVideoID":20261,"CourseChapterTopicPlaylistID":90860,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.635","Text":"In previous videos, we talked about the periodic table."},{"Start":"00:04.635 ","End":"00:09.960","Text":"In this video, we\u0027ll talk about metals and their ions."},{"Start":"00:09.960 ","End":"00:11.880","Text":"Here\u0027s our periodic table."},{"Start":"00:11.880 ","End":"00:15.420","Text":"We\u0027re going to begin by talking about the noble gases."},{"Start":"00:15.420 ","End":"00:20.190","Text":"You recall that the noble gases occupy Group 18,"},{"Start":"00:20.190 ","End":"00:23.130","Text":"which is the right-hand side of the periodic table."},{"Start":"00:23.130 ","End":"00:28.530","Text":"Now, apart from helium in which the 1S orbital is filled out,"},{"Start":"00:28.530 ","End":"00:35.215","Text":"all the others are characterized by having both the s and the p full."},{"Start":"00:35.215 ","End":"00:39.500","Text":"Neon has 2s full and 2p full,"},{"Start":"00:39.500 ","End":"00:42.005","Text":"and argon 3s and 3p,"},{"Start":"00:42.005 ","End":"00:45.125","Text":"and krypton 4s and 4p and so on."},{"Start":"00:45.125 ","End":"00:46.610","Text":"Some of them, in addition,"},{"Start":"00:46.610 ","End":"00:49.265","Text":"have other sub-shells which are full,"},{"Start":"00:49.265 ","End":"00:51.875","Text":"for example, 3d in krypton,"},{"Start":"00:51.875 ","End":"00:54.740","Text":"and 4d in xenon,"},{"Start":"00:54.740 ","End":"00:59.105","Text":"and 5d and 4f in radon."},{"Start":"00:59.105 ","End":"01:05.520","Text":"But the main feature is that the valence s and p are full."},{"Start":"01:11.390 ","End":"01:14.585","Text":"Now, these elements are very stable."},{"Start":"01:14.585 ","End":"01:20.480","Text":"As a result, many ions tend to have the same configuration as the noble gases."},{"Start":"01:20.480 ","End":"01:26.405","Text":"Now, the periodic table is divided into metals, non-metals, and metalloids."},{"Start":"01:26.405 ","End":"01:29.480","Text":"We talked about this in a very early video."},{"Start":"01:29.480 ","End":"01:32.525","Text":"Now, the majority of the elements are metals,"},{"Start":"01:32.525 ","End":"01:35.690","Text":"and metals are good conductors of heat and electricity,"},{"Start":"01:35.690 ","End":"01:38.525","Text":"and are malleable and ductile,"},{"Start":"01:38.525 ","End":"01:41.585","Text":"they can be drawn into long wires."},{"Start":"01:41.585 ","End":"01:45.665","Text":"Now, the non-metals are on the right-hand side of the table."},{"Start":"01:45.665 ","End":"01:48.110","Text":"They are the rare gases,"},{"Start":"01:48.110 ","End":"01:50.585","Text":"there are the halogens,"},{"Start":"01:50.585 ","End":"01:58.570","Text":"and there are these non-metals in green that are in the 14th,"},{"Start":"01:58.610 ","End":"02:04.725","Text":"15th, 16th, and 17th groups."},{"Start":"02:04.725 ","End":"02:10.555","Text":"The ones in green are non-metals and also yellow and pale blue."},{"Start":"02:10.555 ","End":"02:13.435","Text":"All the rest are metals,"},{"Start":"02:13.435 ","End":"02:17.740","Text":"except for the metalloids which are an olive green."},{"Start":"02:17.740 ","End":"02:21.865","Text":"Here, we have them in olive green like a staircase."},{"Start":"02:21.865 ","End":"02:26.530","Text":"These have some metallic and some non-metallic properties."},{"Start":"02:26.530 ","End":"02:29.755","Text":"Now, let\u0027s discuss the metal ions."},{"Start":"02:29.755 ","End":"02:31.675","Text":"Now, they\u0027re always cations."},{"Start":"02:31.675 ","End":"02:33.745","Text":"The metal ions are always cations."},{"Start":"02:33.745 ","End":"02:37.225","Text":"The non-metallic ions are always anions."},{"Start":"02:37.225 ","End":"02:41.745","Text":"Let\u0027s take some examples of Groups 1, 2, and 3."},{"Start":"02:41.745 ","End":"02:45.414","Text":"Group 1, let\u0027s take the example of rubidium,"},{"Start":"02:45.414 ","End":"02:47.250","Text":"but they\u0027re all similar."},{"Start":"02:47.250 ","End":"02:51.680","Text":"That is like krypton with 1 electron the 5s orbital."},{"Start":"02:51.680 ","End":"02:58.380","Text":"It turns into an ion rubidium plus by losing this 5s electron."},{"Start":"02:58.380 ","End":"03:01.415","Text":"In Group 2, for example, calcium,"},{"Start":"03:01.415 ","End":"03:07.290","Text":"which has the argon configuration and 2 electrons and 4s,"},{"Start":"03:07.290 ","End":"03:13.905","Text":"here, the calcium loses 2 electrons from 4s and becomes like argon."},{"Start":"03:13.905 ","End":"03:17.810","Text":"Both rubidium plus and calcium 2 plus have"},{"Start":"03:17.810 ","End":"03:22.890","Text":"the configurations of rare gases or noble gases."},{"Start":"03:30.920 ","End":"03:36.995","Text":"Now, if we jump over to the p block which begins with Group 13,"},{"Start":"03:36.995 ","End":"03:42.475","Text":"then aluminum which has 2 electrons in 3s and 1 in 3p,"},{"Start":"03:42.475 ","End":"03:45.269","Text":"loses all these 3 electrons,"},{"Start":"03:45.269 ","End":"03:47.610","Text":"becomes aluminum 3 plus,"},{"Start":"03:47.610 ","End":"03:52.760","Text":"again with a rare gas configuration, noble gas configuration."},{"Start":"03:52.760 ","End":"03:56.630","Text":"But when we go further down Group 3, for example,"},{"Start":"03:56.630 ","End":"04:03.080","Text":"to indium which now has 2 electrons in 5s and 1 in 5p, here,"},{"Start":"04:03.080 ","End":"04:07.490","Text":"it can lose the 5s and the 5p electrons,"},{"Start":"04:07.490 ","End":"04:08.675","Text":"just like aluminum,"},{"Start":"04:08.675 ","End":"04:11.525","Text":"and to give us indium 3 plus."},{"Start":"04:11.525 ","End":"04:17.000","Text":"But in addition, there\u0027s another possible ion which is indium plus,"},{"Start":"04:17.000 ","End":"04:22.845","Text":"and that\u0027s because we\u0027ve lost only the p electron."},{"Start":"04:22.845 ","End":"04:25.765","Text":"Here, we\u0027ve lost only the 5p electrons."},{"Start":"04:25.765 ","End":"04:32.735","Text":"Now, this phenomenon of losing only a p electron is called the inert-pair effect."},{"Start":"04:32.735 ","End":"04:40.775","Text":"The inert-pair effect is a tendency of atoms to form ions too lower than expected."},{"Start":"04:40.775 ","End":"04:43.310","Text":"Instead of getting 3 plus,"},{"Start":"04:43.310 ","End":"04:45.890","Text":"we get 1 plus,"},{"Start":"04:45.890 ","End":"04:51.595","Text":"and especially occurs for heavier atoms in the p-block such as indium."},{"Start":"04:51.595 ","End":"04:55.189","Text":"The reason for this is that in these heavy atoms,"},{"Start":"04:55.189 ","End":"04:59.300","Text":"the s electrons are much lower in energy than p electrons."},{"Start":"04:59.300 ","End":"05:03.140","Text":"The s electrons act like an inert-pair,"},{"Start":"05:03.140 ","End":"05:04.865","Text":"they stay where they are."},{"Start":"05:04.865 ","End":"05:07.400","Text":"In some books, they call this a lazy"},{"Start":"05:07.400 ","End":"05:16.340","Text":"pair because they can leave but they don\u0027t want to, something like that."},{"Start":"05:16.340 ","End":"05:19.174","Text":"Now, what about the transition metal ions?"},{"Start":"05:19.174 ","End":"05:26.270","Text":"Now, all transition metals lose the s electrons before they lose the d electrons,"},{"Start":"05:26.270 ","End":"05:30.095","Text":"and many transition metals have more than 1 ion."},{"Start":"05:30.095 ","End":"05:33.395","Text":"There are multiple oxidation states."},{"Start":"05:33.395 ","End":"05:35.570","Text":"Let\u0027s take some examples."},{"Start":"05:35.570 ","End":"05:37.250","Text":"Iron, for example,"},{"Start":"05:37.250 ","End":"05:42.410","Text":"has 2 electrons in 4s and 6 electrons in 3d."},{"Start":"05:42.410 ","End":"05:46.845","Text":"The first thing that it loses are the s electrons,"},{"Start":"05:46.845 ","End":"05:51.765","Text":"so we get iron 2 plus which is like argon,"},{"Start":"05:51.765 ","End":"05:54.340","Text":"and 6 electrons in 3d."},{"Start":"05:54.340 ","End":"05:58.735","Text":"But there\u0027s also another ion which is iron 3 plus"},{"Start":"05:58.735 ","End":"06:03.410","Text":"where in addition to losing the 4s electrons,"},{"Start":"06:03.410 ","End":"06:06.820","Text":"we also lose 1 of the d electrons."},{"Start":"06:06.820 ","End":"06:13.564","Text":"Of course, 5 electrons in the d subshell is considered very stable."},{"Start":"06:13.564 ","End":"06:16.010","Text":"Another example is copper."},{"Start":"06:16.010 ","End":"06:20.930","Text":"Here, we have 1 electron 4s and 10 electrons in 3d."},{"Start":"06:20.930 ","End":"06:25.810","Text":"The 4s electron could be lost to give copper plus."},{"Start":"06:25.810 ","End":"06:32.000","Text":"Sometimes, it\u0027s called a pseudo noble gas because in addition to being like a noble gas,"},{"Start":"06:32.000 ","End":"06:34.745","Text":"it also has full d subshell."},{"Start":"06:34.745 ","End":"06:37.760","Text":"Other examples of this are zinc 2 plus,"},{"Start":"06:37.760 ","End":"06:40.795","Text":"silver plus, and gold plus."},{"Start":"06:40.795 ","End":"06:43.365","Text":"But in addition to copper plus,"},{"Start":"06:43.365 ","End":"06:45.620","Text":"there\u0027s also copper 2 plus."},{"Start":"06:45.620 ","End":"06:53.045","Text":"There, not only have the s electrons being lost but also 1 electron from the 3d."},{"Start":"06:53.045 ","End":"06:54.950","Text":"Let\u0027s take an example."},{"Start":"06:54.950 ","End":"06:58.460","Text":"What is the configuration of chromium 3 plus?"},{"Start":"06:58.460 ","End":"07:02.195","Text":"We have to look and see what the configuration of chromium is."},{"Start":"07:02.195 ","End":"07:04.355","Text":"Remember, it\u0027s an exception."},{"Start":"07:04.355 ","End":"07:06.039","Text":"It looks like argon,"},{"Start":"07:06.039 ","End":"07:10.290","Text":"1 electron 4s and 5 electrons in 3d."},{"Start":"07:10.290 ","End":"07:16.200","Text":"It has 2 half-full subshells and we have to lose 3 electrons."},{"Start":"07:16.200 ","End":"07:18.630","Text":"Always, you first lose the electrons from"},{"Start":"07:18.630 ","End":"07:22.970","Text":"the 4s ad then we need to lose another 2 electrons so"},{"Start":"07:22.970 ","End":"07:30.045","Text":"they come out from 3d and we\u0027re left with 3d with 3 electrons in it."},{"Start":"07:30.045 ","End":"07:34.280","Text":"This is the configuration of chromium 3 plus,"},{"Start":"07:34.280 ","End":"07:38.345","Text":"it\u0027s like argon, and 3 electrons in 3d."},{"Start":"07:38.345 ","End":"07:44.850","Text":"In this video, we talked about metals and their ions."}],"ID":21054},{"Watched":false,"Name":"Nonmetals and their Ions","Duration":"2m 46s","ChapterTopicVideoID":20262,"CourseChapterTopicPlaylistID":90860,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:01.410","Text":"In the previous video,"},{"Start":"00:01.410 ","End":"00:03.600","Text":"we talked about metal ions,"},{"Start":"00:03.600 ","End":"00:06.765","Text":"in this video we\u0027ll talk about nonmetal ions."},{"Start":"00:06.765 ","End":"00:09.720","Text":"Here\u0027s our periodic table, once again,"},{"Start":"00:09.720 ","End":"00:14.685","Text":"just to remind us that non metals are on the right hand side of the table,"},{"Start":"00:14.685 ","End":"00:17.475","Text":"there are these elements in green,"},{"Start":"00:17.475 ","End":"00:19.740","Text":"in groups 14,"},{"Start":"00:19.740 ","End":"00:23.300","Text":"15 and 16, in group 17,"},{"Start":"00:23.300 ","End":"00:27.380","Text":"the halogens, and group 18, the noble gases."},{"Start":"00:27.380 ","End":"00:29.165","Text":"These are our nonmetals,"},{"Start":"00:29.165 ","End":"00:31.535","Text":"all the rest are metals,"},{"Start":"00:31.535 ","End":"00:34.070","Text":"and of course a few metalloids."},{"Start":"00:34.070 ","End":"00:38.060","Text":"Now, non metals are non conductors of heat and electricity,"},{"Start":"00:38.060 ","End":"00:40.475","Text":"they don\u0027t conduct heat and electricity,"},{"Start":"00:40.475 ","End":"00:43.580","Text":"many of them are gases, for example, fluorine,"},{"Start":"00:43.580 ","End":"00:49.285","Text":"chlorine, all the noble gases, oxygen,"},{"Start":"00:49.285 ","End":"00:53.720","Text":"that\u0027s the main ones and bromine,"},{"Start":"00:53.720 ","End":"00:58.940","Text":"for example, is a liquid at room temperature and some are solids, for example,"},{"Start":"00:58.940 ","End":"01:01.175","Text":"carbon, phosphorus,"},{"Start":"01:01.175 ","End":"01:03.800","Text":"and sulfur and if they are solids,"},{"Start":"01:03.800 ","End":"01:05.275","Text":"they are brittle,"},{"Start":"01:05.275 ","End":"01:10.105","Text":"you can\u0027t make them into a thin sheet or into a long wire."},{"Start":"01:10.105 ","End":"01:12.430","Text":"Now, what about their ions?"},{"Start":"01:12.430 ","End":"01:16.980","Text":"Let\u0027s take some examples from groups 15, 16 and 17."},{"Start":"01:16.980 ","End":"01:19.485","Text":"In group 15 we have nitrogen,"},{"Start":"01:19.485 ","End":"01:26.370","Text":"which has 2 electrons in 2s and 3 electrons in 2p and that forms"},{"Start":"01:26.370 ","End":"01:33.310","Text":"the nitrogen 3 minus ion in which we have another 3 electrons in 2p,"},{"Start":"01:33.310 ","End":"01:42.645","Text":"so we have 2p^6 and 2s^2 and that\u0027s the configuration of neon,"},{"Start":"01:42.645 ","End":"01:45.650","Text":"so that\u0027s not particularly common."},{"Start":"01:45.650 ","End":"01:48.710","Text":"In group 16, we have oxygen,"},{"Start":"01:48.710 ","End":"01:54.800","Text":"which has 2 electrons in 2s and 4 electrons in 2p and when it becomes an ion,"},{"Start":"01:54.800 ","End":"01:58.880","Text":"it accepts another 2 electrons into the 2p,"},{"Start":"01:58.880 ","End":"02:05.300","Text":"so now it has a configuration of neon and that\u0027s the O^2 minus ion,"},{"Start":"02:05.300 ","End":"02:06.940","Text":"which is very common."},{"Start":"02:06.940 ","End":"02:09.465","Text":"In group 17 for example,"},{"Start":"02:09.465 ","End":"02:11.880","Text":"chlorine has 2 electrons in"},{"Start":"02:11.880 ","End":"02:17.060","Text":"3s and 5 electrons in 3p and it can accept another electron into"},{"Start":"02:17.060 ","End":"02:20.945","Text":"the 3p so that it now has a configuration of"},{"Start":"02:20.945 ","End":"02:26.810","Text":"argon and that\u0027s chlorine minus and remind you of the names,"},{"Start":"02:26.810 ","End":"02:32.120","Text":"this is called nitride, oxide,"},{"Start":"02:32.120 ","End":"02:40.310","Text":"and chloride and they\u0027re all anions, negatively charged anions."},{"Start":"02:40.310 ","End":"02:46.170","Text":"In this video, we talked about the non metals and their ions."}],"ID":21055}],"Thumbnail":null,"ID":90860},{"Name":"Sizes of Atoms and Ions","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Atomic Radius","Duration":"7m 11s","ChapterTopicVideoID":20265,"CourseChapterTopicPlaylistID":90861,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.295","Text":"In the previous videos,"},{"Start":"00:02.295 ","End":"00:04.815","Text":"we talked about metals and non-metals."},{"Start":"00:04.815 ","End":"00:08.625","Text":"In this video, we\u0027ll discuss the atomic radius."},{"Start":"00:08.625 ","End":"00:10.680","Text":"Now according to quantum theory,"},{"Start":"00:10.680 ","End":"00:13.485","Text":"an atom doesn\u0027t have a defined size."},{"Start":"00:13.485 ","End":"00:19.800","Text":"That\u0027s because we never know where 100 percent probability of finding the electron is."},{"Start":"00:19.800 ","End":"00:23.340","Text":"However, when an atom is combined with other atoms,"},{"Start":"00:23.340 ","End":"00:26.580","Text":"we can measure the distance between 2 neighboring atoms,"},{"Start":"00:26.580 ","End":"00:29.685","Text":"and then estimate the atomic radius."},{"Start":"00:29.685 ","End":"00:35.355","Text":"Let\u0027s start with a covalent radius that occurs in non-metals or metalloids."},{"Start":"00:35.355 ","End":"00:38.940","Text":"The covalent radius is half the distance between the centers of"},{"Start":"00:38.940 ","End":"00:44.115","Text":"2 identical atoms connected by a single covalent bond."},{"Start":"00:44.115 ","End":"00:49.430","Text":"Now, we haven\u0027t yet learned what covalent bonds are, but at the moment,"},{"Start":"00:49.430 ","End":"00:58.160","Text":"just to know that\u0027s the sort of bond we have in H_2 or Cl_2 or F_2."},{"Start":"00:58.160 ","End":"01:02.650","Text":"Let\u0027s take an example of chlorine gas, the Cl_2."},{"Start":"01:02.650 ","End":"01:07.760","Text":"Here we have 2 chlorine atoms and we\u0027ve drawn them 1 beside the other."},{"Start":"01:07.760 ","End":"01:12.530","Text":"Now, if we draw a line between the 2 centers,"},{"Start":"01:12.530 ","End":"01:14.000","Text":"between the 2 nuclei,"},{"Start":"01:14.000 ","End":"01:22.740","Text":"then the radius will be half that distance here."},{"Start":"01:22.790 ","End":"01:27.365","Text":"The inter-nuclear distance is 198 picometers,"},{"Start":"01:27.365 ","End":"01:30.830","Text":"the covalent radius of chlorine will be half of that,"},{"Start":"01:30.830 ","End":"01:32.510","Text":"which is 99 picometers,"},{"Start":"01:32.510 ","End":"01:37.135","Text":"and recall that picometer is 10^-12 meters."},{"Start":"01:37.135 ","End":"01:42.980","Text":"There\u0027s also metallic radius and metallic radius is half the distance between"},{"Start":"01:42.980 ","End":"01:48.935","Text":"the centers of 2 neighboring atoms in a solid metal sample."},{"Start":"01:48.935 ","End":"01:51.695","Text":"Let us take an example of sodium metal."},{"Start":"01:51.695 ","End":"01:56.404","Text":"Here are 2 sodium atoms in sodium metal, and again,"},{"Start":"01:56.404 ","End":"02:02.610","Text":"we\u0027ll draw the distance between the 2 centers."},{"Start":"02:04.730 ","End":"02:08.955","Text":"The radius is this distance here,"},{"Start":"02:08.955 ","End":"02:13.205","Text":"so the inter-nuclear distance is 372 picometers."},{"Start":"02:13.205 ","End":"02:15.635","Text":"The metallic radius is half of that,"},{"Start":"02:15.635 ","End":"02:18.410","Text":"and that\u0027s a 186 picometers."},{"Start":"02:18.410 ","End":"02:23.570","Text":"Now, those are Van der Waals radius and that occurs in noble gases."},{"Start":"02:23.570 ","End":"02:26.190","Text":"Noble gases don\u0027t form chemical bonds,"},{"Start":"02:26.190 ","End":"02:28.860","Text":"that\u0027s why they\u0027re called noble, they standalone."},{"Start":"02:28.860 ","End":"02:35.870","Text":"But the radii of solidified noble gases are larger than covalent radii,"},{"Start":"02:35.870 ","End":"02:41.325","Text":"so don\u0027t take them into account when testing the trends."},{"Start":"02:41.325 ","End":"02:43.200","Text":"Let us look at the trends."},{"Start":"02:43.200 ","End":"02:45.935","Text":"At the moment, we\u0027re just talking about the main group elements,"},{"Start":"02:45.935 ","End":"02:48.005","Text":"that\u0027s the S and P blocks."},{"Start":"02:48.005 ","End":"02:52.160","Text":"Now atomic radii generally decrease from left to right across"},{"Start":"02:52.160 ","End":"02:57.310","Text":"a period and increase down a group that\u0027s illustrated here,"},{"Start":"02:57.310 ","End":"03:00.350","Text":"so the arrow points to the place where"},{"Start":"03:00.350 ","End":"03:04.280","Text":"the atomic radius is greatest and that\u0027s on the left hand side."},{"Start":"03:04.280 ","End":"03:06.485","Text":"Let\u0027s take some examples."},{"Start":"03:06.485 ","End":"03:10.850","Text":"The second period are all the distances are in picometers."},{"Start":"03:10.850 ","End":"03:12.890","Text":"We have lithium is 152,"},{"Start":"03:12.890 ","End":"03:17.360","Text":"beryllium 113, boron 88, nitrogen 75,"},{"Start":"03:17.360 ","End":"03:20.630","Text":"oxygen 66, and fluorine 58,"},{"Start":"03:20.630 ","End":"03:26.840","Text":"so we can see that the radius is decreasing across the period."},{"Start":"03:26.840 ","End":"03:29.175","Text":"Here\u0027s a group 2."},{"Start":"03:29.175 ","End":"03:30.660","Text":"We start with beryllium,"},{"Start":"03:30.660 ","End":"03:33.945","Text":"which is 113, then magnesium 160,"},{"Start":"03:33.945 ","End":"03:39.840","Text":"calcium 197, strontium 215, and barium 217."},{"Start":"03:39.840 ","End":"03:45.184","Text":"We can see that the radius is increasing down the group."},{"Start":"03:45.184 ","End":"03:48.560","Text":"Now, what are the explanations of this behavior?"},{"Start":"03:48.560 ","End":"03:50.540","Text":"Let\u0027s start with the easy one."},{"Start":"03:50.540 ","End":"03:52.385","Text":"As we go down the group,"},{"Start":"03:52.385 ","End":"03:56.920","Text":"the outermost electron is in a shell of increasing principle quantum number,"},{"Start":"03:56.920 ","End":"03:59.625","Text":"and it\u0027s there for further from the nucleus,"},{"Start":"03:59.625 ","End":"04:02.250","Text":"so that\u0027s fairly obvious."},{"Start":"04:02.250 ","End":"04:07.385","Text":"Now what about the decrease across the period how can we explain that?"},{"Start":"04:07.385 ","End":"04:11.480","Text":"We can explain it by considering the effect of nuclear charge,"},{"Start":"04:11.480 ","End":"04:15.460","Text":"this is a concept we\u0027ve talked about in previous videos."},{"Start":"04:15.460 ","End":"04:20.330","Text":"Let us consider the effect of nuclear charge of the outermost electron."},{"Start":"04:20.330 ","End":"04:24.035","Text":"This is again for the main group elements S and P blocks."},{"Start":"04:24.035 ","End":"04:28.985","Text":"The effective nuclear charge increases from left to right across a period,"},{"Start":"04:28.985 ","End":"04:31.505","Text":"and increases down a group."},{"Start":"04:31.505 ","End":"04:33.695","Text":"This is in blue,"},{"Start":"04:33.695 ","End":"04:37.655","Text":"the blue is effective nuclear charge."},{"Start":"04:37.655 ","End":"04:41.960","Text":"You can see it\u0027s increasing from left to right and"},{"Start":"04:41.960 ","End":"04:47.660","Text":"increasing also from the top to the bottom, down the group."},{"Start":"04:47.660 ","End":"04:53.155","Text":"The red arrow refers to the atomic radius,"},{"Start":"04:53.155 ","End":"05:00.550","Text":"so blue is Zeff effective and red is atomic radius."},{"Start":"05:00.550 ","End":"05:02.885","Text":"Now across the period,"},{"Start":"05:02.885 ","End":"05:05.195","Text":"the new electrons in the same shell,"},{"Start":"05:05.195 ","End":"05:06.950","Text":"remember we went down the group,"},{"Start":"05:06.950 ","End":"05:08.570","Text":"they were in a different shell,"},{"Start":"05:08.570 ","End":"05:12.215","Text":"so they were obviously further away from the nucleus."},{"Start":"05:12.215 ","End":"05:13.775","Text":"But across the period,"},{"Start":"05:13.775 ","End":"05:17.035","Text":"the new electrons are in the same shell,"},{"Start":"05:17.035 ","End":"05:20.035","Text":"and it all about the same distance from the nucleus,"},{"Start":"05:20.035 ","End":"05:22.290","Text":"but they\u0027re spread out and not"},{"Start":"05:22.290 ","End":"05:25.340","Text":"effective in shielding each other from the nuclear charge,"},{"Start":"05:25.340 ","End":"05:30.680","Text":"so that the effective nuclear charge increases as does of course,"},{"Start":"05:30.680 ","End":"05:32.660","Text":"the real nuclear charge,"},{"Start":"05:32.660 ","End":"05:37.360","Text":"so Zeff effective increases."},{"Start":"05:38.270 ","End":"05:43.550","Text":"We see Zeff effective increasing and the radius decreasing."},{"Start":"05:43.550 ","End":"05:47.345","Text":"As the effective nuclear charge increases,"},{"Start":"05:47.345 ","End":"05:52.615","Text":"the atom becomes more compact with a smaller atomic radius."},{"Start":"05:52.615 ","End":"05:59.000","Text":"We see the opposite behaviors of effective nuclear charge and the radius."},{"Start":"05:59.000 ","End":"06:01.384","Text":"Now what about the transition metals?"},{"Start":"06:01.384 ","End":"06:04.729","Text":"Here, the atomic radius is approximately constant"},{"Start":"06:04.729 ","End":"06:08.105","Text":"across a period apart from a few exceptions,"},{"Start":"06:08.105 ","End":"06:10.115","Text":"so let\u0027s take an example."},{"Start":"06:10.115 ","End":"06:14.260","Text":"The example is Fe, Co, Ni."},{"Start":"06:14.260 ","End":"06:21.795","Text":"Iron is like argon and has 6 electrons in 3_d and 2 electrons in 4_s."},{"Start":"06:21.795 ","End":"06:25.460","Text":"Cobalt is similar, the same except it has"},{"Start":"06:25.460 ","End":"06:30.150","Text":"several electrons in 3_d and nickel is again the same,"},{"Start":"06:30.150 ","End":"06:32.280","Text":"but has 8 electrons in 3_d,"},{"Start":"06:32.280 ","End":"06:38.930","Text":"so the only difference between these 3 atoms is the number of electrons in 3_d."},{"Start":"06:38.930 ","End":"06:45.280","Text":"All the electrons are added in the d subshell and don\u0027t shield the outer electrons,"},{"Start":"06:45.280 ","End":"06:48.620","Text":"so the effective nuclear charge is approximately constant,"},{"Start":"06:48.620 ","End":"06:50.015","Text":"is approximately 2,"},{"Start":"06:50.015 ","End":"06:54.335","Text":"and so are the radii there are 124 for iron,"},{"Start":"06:54.335 ","End":"06:59.275","Text":"125 for cobalt, and 125 also for nickel."},{"Start":"06:59.275 ","End":"07:06.395","Text":"In transition metals, the atomic radius is approximately constant across the period."},{"Start":"07:06.395 ","End":"07:11.580","Text":"In this video, we discussed the trends in the atomic radii."}],"ID":21058},{"Watched":false,"Name":"Exercise 1","Duration":"2m 25s","ChapterTopicVideoID":22994,"CourseChapterTopicPlaylistID":90861,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.045","Text":"Hi. We\u0027re going to solve the following exercise."},{"Start":"00:03.045 ","End":"00:05.459","Text":"Indicate the atom with a larger radius,"},{"Start":"00:05.459 ","End":"00:07.530","Text":"a, chlorine or selenium."},{"Start":"00:07.530 ","End":"00:13.350","Text":"Before we start with a, we\u0027re just going to look at our periodic table."},{"Start":"00:13.350 ","End":"00:16.665","Text":"Then our periodic table we have a general trend,"},{"Start":"00:16.665 ","End":"00:18.960","Text":"which is correct for the main group elements,"},{"Start":"00:18.960 ","End":"00:20.625","Text":"meaning the S and the P blocks."},{"Start":"00:20.625 ","End":"00:22.275","Text":"As we go down a group,"},{"Start":"00:22.275 ","End":"00:31.775","Text":"the atomic radius increases and as we go across a period from left to right,"},{"Start":"00:31.775 ","End":"00:35.280","Text":"the atomic radius decreases,"},{"Start":"00:36.640 ","End":"00:40.130","Text":"meaning it increases towards the left."},{"Start":"00:40.130 ","End":"00:41.990","Text":"If we look at this general trend,"},{"Start":"00:41.990 ","End":"00:45.140","Text":"we accept that the atomic radius to increase as we are"},{"Start":"00:45.140 ","End":"00:48.620","Text":"lower down and more to the left of the periodic table."},{"Start":"00:48.620 ","End":"00:50.390","Text":"Now, we\u0027re going to look at the periodic table."},{"Start":"00:50.390 ","End":"00:55.100","Text":"You can look at yours and find chlorine and selenium and you will find that selenium"},{"Start":"00:55.100 ","End":"01:00.260","Text":"compared to chlorine is more to the bottom of the periodic table and more to the left,"},{"Start":"01:00.260 ","End":"01:05.420","Text":"meaning that an, a Selenium is the larger atom."},{"Start":"01:05.420 ","End":"01:07.385","Text":"Now we\u0027re going to look at b."},{"Start":"01:07.385 ","End":"01:11.300","Text":"Here we need to decide if sodium or magnesium is the larger atom."},{"Start":"01:11.300 ","End":"01:14.030","Text":"Now again, if you will have a look at your periodic table,"},{"Start":"01:14.030 ","End":"01:17.780","Text":"you will see that sodium and magnesium are in the same period."},{"Start":"01:17.780 ","End":"01:20.600","Text":"However, sodium is more to the left,"},{"Start":"01:20.600 ","End":"01:24.670","Text":"therefore, sodium is larger radius."},{"Start":"01:24.670 ","End":"01:29.059","Text":"In c, we\u0027re asked about rubidium and magnesium."},{"Start":"01:29.059 ","End":"01:31.730","Text":"Now again, take a look at your periodic table and you will see that"},{"Start":"01:31.730 ","End":"01:35.930","Text":"rubidium is also lower down and also to the left of magnesium."},{"Start":"01:35.930 ","End":"01:38.910","Text":"Therefore, rubidium is the larger atom."},{"Start":"01:38.910 ","End":"01:43.120","Text":"In d, we have silicon or tin."},{"Start":"01:43.120 ","End":"01:45.200","Text":"Now again, in your periodic table,"},{"Start":"01:45.200 ","End":"01:47.330","Text":"you will see that both of these are in the same group."},{"Start":"01:47.330 ","End":"01:49.910","Text":"Silicon and tin are found in the same group."},{"Start":"01:49.910 ","End":"01:53.105","Text":"However, tin is lower down."},{"Start":"01:53.105 ","End":"01:57.325","Text":"Therefore, tin is the larger atom since it\u0027s below the silicon."},{"Start":"01:57.325 ","End":"02:00.585","Text":"In e, we have indium or Sulfur."},{"Start":"02:00.585 ","End":"02:02.510","Text":"Again, in your periodic table,"},{"Start":"02:02.510 ","End":"02:07.180","Text":"you will see that indium is lower down and to the left of the Sulfur."},{"Start":"02:07.180 ","End":"02:10.275","Text":"That makes indium the larger atom."},{"Start":"02:10.275 ","End":"02:14.404","Text":"Again, the atom with the larger radius is in a, selenium,"},{"Start":"02:14.404 ","End":"02:16.295","Text":"and b sodium,"},{"Start":"02:16.295 ","End":"02:19.775","Text":"c rubidium, d tin,"},{"Start":"02:19.775 ","End":"02:22.030","Text":"and in e Indium."},{"Start":"02:22.030 ","End":"02:23.510","Text":"These are our final answers."},{"Start":"02:23.510 ","End":"02:26.130","Text":"Thank you very much for watching."}],"ID":23844},{"Watched":false,"Name":"Exercise 2","Duration":"1m 48s","ChapterTopicVideoID":22995,"CourseChapterTopicPlaylistID":90861,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.355","Text":"Hey, we\u0027re going to solve the following exercise."},{"Start":"00:02.355 ","End":"00:07.140","Text":"Which is the largest atom in period 5 and the smallest atom in group 2?"},{"Start":"00:07.140 ","End":"00:09.810","Text":"If this is our periodic table,"},{"Start":"00:09.810 ","End":"00:15.330","Text":"first we\u0027re going to look at the largest atom in period 5 for the main group elements,"},{"Start":"00:15.330 ","End":"00:17.085","Text":"meaning the S and the P blocks."},{"Start":"00:17.085 ","End":"00:20.260","Text":"As we go from left to right in a period,"},{"Start":"00:20.260 ","End":"00:22.650","Text":"the atomic radius decreases."},{"Start":"00:22.650 ","End":"00:26.460","Text":"Therefore, since we want the largest atom in period 5 we will go to period"},{"Start":"00:26.460 ","End":"00:30.885","Text":"5 and the atom which is most of the left is going to be our largest atom."},{"Start":"00:30.885 ","End":"00:33.410","Text":"In our case, if you look at your periodic table,"},{"Start":"00:33.410 ","End":"00:36.319","Text":"you will find that rubidium is found most to the left,"},{"Start":"00:36.319 ","End":"00:43.180","Text":"so the largest atom in period 5 is rubidium."},{"Start":"00:48.500 ","End":"00:52.335","Text":"Now, we have to find the smallest atom in group 2."},{"Start":"00:52.335 ","End":"00:55.340","Text":"Now we\u0027re going to take the general trend for the groups."},{"Start":"00:55.340 ","End":"00:58.610","Text":"As we go down a group from top to bottom,"},{"Start":"00:58.610 ","End":"01:02.010","Text":"the atomic radius increases."},{"Start":"01:02.360 ","End":"01:07.140","Text":"If we want to find the smallest atom in group 2,"},{"Start":"01:07.140 ","End":"01:11.850","Text":"we go to group 2 on the periodic table and the smallest atom is going to be the atom,"},{"Start":"01:11.850 ","End":"01:18.135","Text":"which is furthest up since the atomic radius increases from top to bottom."},{"Start":"01:18.135 ","End":"01:19.560","Text":"In group 2,"},{"Start":"01:19.560 ","End":"01:23.135","Text":"the atom which is highest up is beryllium."},{"Start":"01:23.135 ","End":"01:34.740","Text":"Therefore, beryllium is the smallest atom in group 2."},{"Start":"01:36.460 ","End":"01:40.010","Text":"Again, rubidium is the largest atom in period"},{"Start":"01:40.010 ","End":"01:44.915","Text":"5 and beryllium is the smallest atom in group 2."},{"Start":"01:44.915 ","End":"01:46.774","Text":"These are our final answers."},{"Start":"01:46.774 ","End":"01:49.530","Text":"Thank you very much for watching."}],"ID":23845},{"Watched":false,"Name":"Exercise 3","Duration":"2m 27s","ChapterTopicVideoID":22996,"CourseChapterTopicPlaylistID":90861,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.894","Text":"Hi, we\u0027re going to solve the following exercise."},{"Start":"00:02.894 ","End":"00:06.480","Text":"Arrange the atoms in order of increasing radius: oxygen,"},{"Start":"00:06.480 ","End":"00:09.240","Text":"phosphorus, strontium, and rubidium."},{"Start":"00:09.240 ","End":"00:12.060","Text":"If you look at your periodic table at the main group elements,"},{"Start":"00:12.060 ","End":"00:13.650","Text":"which is the S and P blocks,"},{"Start":"00:13.650 ","End":"00:17.370","Text":"there\u0027s a general trend as we go down in a group from top to bottom,"},{"Start":"00:17.370 ","End":"00:20.620","Text":"the atomic radius increases."},{"Start":"00:21.950 ","End":"00:25.940","Text":"As we go from left to right along a period,"},{"Start":"00:25.940 ","End":"00:30.390","Text":"the atomic radius decreases."},{"Start":"00:30.880 ","End":"00:35.240","Text":"We want to find the order of increasing radius for the following elements."},{"Start":"00:35.240 ","End":"00:39.290","Text":"We\u0027ll take a look at each one and see where it is located in the periodic table."},{"Start":"00:39.290 ","End":"00:45.640","Text":"The oxygen is located in Period 2 Group 16,"},{"Start":"00:45.640 ","End":"00:52.215","Text":"phosphorus is located in Period 3 Group 15,"},{"Start":"00:52.215 ","End":"01:00.070","Text":"rubidium is located in Period 5 Group 1,"},{"Start":"01:00.140 ","End":"01:07.430","Text":"and strontium is located in Period 5 Group 2."},{"Start":"01:07.430 ","End":"01:12.415","Text":"Now we\u0027re going to look at the location of the atoms and see which is the smallest."},{"Start":"01:12.415 ","End":"01:14.845","Text":"If we compare locations of all the atoms,"},{"Start":"01:14.845 ","End":"01:19.600","Text":"we can see that the oxygen is most to the right since he\u0027s in"},{"Start":"01:19.600 ","End":"01:25.360","Text":"the largest group and also most of the top of the periodic table since he\u0027s in Period 2."},{"Start":"01:25.360 ","End":"01:29.140","Text":"Therefore, the oxygen will be the smallest atom again,"},{"Start":"01:29.140 ","End":"01:31.690","Text":"since it\u0027s located most to the right and"},{"Start":"01:31.690 ","End":"01:34.450","Text":"to the top of the periodic table compared to the other elements."},{"Start":"01:34.450 ","End":"01:37.585","Text":"The next element is phosphorus."},{"Start":"01:37.585 ","End":"01:41.110","Text":"Again, it\u0027s located to the right,"},{"Start":"01:41.110 ","End":"01:44.050","Text":"it\u0027s in Group 15, and it\u0027s in Period 3,"},{"Start":"01:44.050 ","End":"01:45.235","Text":"so it\u0027s high up."},{"Start":"01:45.235 ","End":"01:47.830","Text":"Next, if we compare our rubidium and strontium,"},{"Start":"01:47.830 ","End":"01:49.760","Text":"they\u0027re both in the same period,"},{"Start":"01:49.760 ","End":"01:51.855","Text":"in Period 5, however,"},{"Start":"01:51.855 ","End":"01:55.005","Text":"the rubidium is in Group 1 and the strontium is in Group 2,"},{"Start":"01:55.005 ","End":"01:58.950","Text":"meaning they\u0027re one next to the other."},{"Start":"01:58.950 ","End":"02:02.255","Text":"The rubidium will be here and the strontium is here."},{"Start":"02:02.255 ","End":"02:04.190","Text":"Since the rubidium is in Group 1,"},{"Start":"02:04.190 ","End":"02:07.010","Text":"it\u0027s more to the left of the strontium therefore,"},{"Start":"02:07.010 ","End":"02:09.095","Text":"this makes the rubidium the larger atom."},{"Start":"02:09.095 ","End":"02:15.225","Text":"The strontium is next in line and the rubidium is the largest."},{"Start":"02:15.225 ","End":"02:18.980","Text":"Again, the oxygen is the smallest than the phosphorus than"},{"Start":"02:18.980 ","End":"02:23.720","Text":"the strontium and the largest atom here is the rubidium."},{"Start":"02:23.720 ","End":"02:25.400","Text":"That is our final answer."},{"Start":"02:25.400 ","End":"02:28.080","Text":"Thank you very much for watching."}],"ID":23846},{"Watched":false,"Name":"Ionic Radius","Duration":"7m 27s","ChapterTopicVideoID":20266,"CourseChapterTopicPlaylistID":90861,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:01.440","Text":"In the previous video,"},{"Start":"00:01.440 ","End":"00:03.840","Text":"we talked about the atomic radius."},{"Start":"00:03.840 ","End":"00:07.515","Text":"In this video, we\u0027ll talk about the ionic radius."},{"Start":"00:07.515 ","End":"00:11.070","Text":"We\u0027re going to talk about the ionic radius."},{"Start":"00:11.070 ","End":"00:14.880","Text":"Now we can\u0027t use the same procedure as for the atomic radius,"},{"Start":"00:14.880 ","End":"00:18.960","Text":"since 2 identical ions are never adjacent to each other,"},{"Start":"00:18.960 ","End":"00:22.370","Text":"we never have sodium plus,"},{"Start":"00:22.370 ","End":"00:25.760","Text":"for example, next to another sodium plus,"},{"Start":"00:25.760 ","End":"00:27.560","Text":"they would repel each other."},{"Start":"00:27.560 ","End":"00:30.320","Text":"This is the procedure we use."},{"Start":"00:30.320 ","End":"00:33.530","Text":"First, we measure the distance between the centers of"},{"Start":"00:33.530 ","End":"00:37.990","Text":"a cation and a neighboring oxygen ion, O_2 minus."},{"Start":"00:37.990 ","End":"00:42.545","Text":"We take the radius of the oxygen anion to be 140 picometers,"},{"Start":"00:42.545 ","End":"00:45.185","Text":"and then calculate the radius of the cation."},{"Start":"00:45.185 ","End":"00:49.800","Text":"Let\u0027s take an example, magnesium oxide."},{"Start":"00:49.800 ","End":"00:54.340","Text":"Draw the magnesium 2 plus in blue,"},{"Start":"00:55.610 ","End":"00:59.430","Text":"and oxygen in red,"},{"Start":"00:59.430 ","End":"01:02.235","Text":"the O_2 minus in red."},{"Start":"01:02.235 ","End":"01:11.660","Text":"We\u0027ll see later why that the oxygen 2 minus is much larger than magnesium 2 plus."},{"Start":"01:11.660 ","End":"01:15.890","Text":"We can draw a line between the 2 centers."},{"Start":"01:15.890 ","End":"01:21.170","Text":"The distance between them is 212 picometers."},{"Start":"01:21.170 ","End":"01:28.400","Text":"The radius of magnesium 2 plus is 212 minus a 140 picometers,"},{"Start":"01:28.400 ","End":"01:33.935","Text":"which is the radius of the O_2 minus and that gives us 72 picometers."},{"Start":"01:33.935 ","End":"01:36.815","Text":"In this way, we can calculate the radius of"},{"Start":"01:36.815 ","End":"01:41.345","Text":"magnesium 2 plus and indeed of any other cation."},{"Start":"01:41.345 ","End":"01:45.875","Text":"Then from the cations we can get to other anions and so on."},{"Start":"01:45.875 ","End":"01:51.200","Text":"Now, what\u0027s the relative size of a cation compared to its parent atom?"},{"Start":"01:51.200 ","End":"01:55.805","Text":"Well, cations are always smaller than their parent atom."},{"Start":"01:55.805 ","End":"02:00.005","Text":"The nuclear charge pulls the remaining electrons closer."},{"Start":"02:00.005 ","End":"02:02.555","Text":"Let\u0027s take some examples."},{"Start":"02:02.555 ","End":"02:06.530","Text":"Sodium has a radius of 154 picometers,"},{"Start":"02:06.530 ","End":"02:10.160","Text":"and sodium plus has a radius of 102,"},{"Start":"02:10.160 ","End":"02:12.980","Text":"so it\u0027s smaller than sodium."},{"Start":"02:12.980 ","End":"02:18.020","Text":"Magnesium 2 plus has a radius of 72 picometers,"},{"Start":"02:18.020 ","End":"02:20.615","Text":"which is smaller than magnesium,"},{"Start":"02:20.615 ","End":"02:22.625","Text":"which has a radius of 160."},{"Start":"02:22.625 ","End":"02:26.900","Text":"An aluminum 3 plus has a radius of 54 picometers,"},{"Start":"02:26.900 ","End":"02:29.600","Text":"which is much smaller than that of aluminum,"},{"Start":"02:29.600 ","End":"02:31.790","Text":"which is a 143 picometers."},{"Start":"02:31.790 ","End":"02:36.890","Text":"We see that the cations are always smaller than the parent atom."},{"Start":"02:36.890 ","End":"02:40.155","Text":"Now let\u0027s talk about the trends,"},{"Start":"02:40.155 ","End":"02:43.415","Text":"and again, we\u0027re considering the main group atoms."},{"Start":"02:43.415 ","End":"02:50.180","Text":"Ionic radius of cations generally decreases across the periodic table,"},{"Start":"02:50.180 ","End":"02:52.190","Text":"as does the atomic radius."},{"Start":"02:52.190 ","End":"02:55.270","Text":"However, the changes in their ionic radius"},{"Start":"02:55.270 ","End":"02:58.840","Text":"are much greater than those in the atomic radius,"},{"Start":"02:58.840 ","End":"03:03.380","Text":"and that\u0027s because the charge increases from left to right."},{"Start":"03:03.380 ","End":"03:04.850","Text":"However, in a group,"},{"Start":"03:04.850 ","End":"03:08.630","Text":"cations in the same group all have the same charge."},{"Start":"03:08.630 ","End":"03:11.435","Text":"The radius increases down the group,"},{"Start":"03:11.435 ","End":"03:16.085","Text":"just as does the atomic radius. Here we have it."},{"Start":"03:16.085 ","End":"03:20.420","Text":"The ionic radius decreases from left to right,"},{"Start":"03:20.420 ","End":"03:24.410","Text":"and increases from down a group,"},{"Start":"03:24.410 ","End":"03:26.585","Text":"increases from the top to the bottom."},{"Start":"03:26.585 ","End":"03:29.900","Text":"Here\u0027s some examples. The third period,"},{"Start":"03:29.900 ","End":"03:32.330","Text":"for example, sodium plus is 102,"},{"Start":"03:32.330 ","End":"03:34.565","Text":"magnesium 2 plus, 72,"},{"Start":"03:34.565 ","End":"03:37.130","Text":"and aluminum 3 plus 54,"},{"Start":"03:37.130 ","End":"03:43.250","Text":"so the radius decreases as the charge increases."},{"Start":"03:43.250 ","End":"03:46.055","Text":"We go from plus 1 to plus 2 to plus 3,"},{"Start":"03:46.055 ","End":"03:48.305","Text":"and the radius decreases."},{"Start":"03:48.305 ","End":"03:51.860","Text":"Group 1, lithium is 76,"},{"Start":"03:51.860 ","End":"03:56.295","Text":"sodium 102, potassium 138,"},{"Start":"03:56.295 ","End":"04:00.650","Text":"rubidium 122, cesium 167."},{"Start":"04:00.650 ","End":"04:08.105","Text":"We see that the radius of these ions increases as we go down the group,"},{"Start":"04:08.105 ","End":"04:10.640","Text":"it increases as we go down the group."},{"Start":"04:10.640 ","End":"04:12.575","Text":"Now what about the anions?"},{"Start":"04:12.575 ","End":"04:17.315","Text":"What is the relative size of an anion compared to its parent atom?"},{"Start":"04:17.315 ","End":"04:19.595","Text":"Now here we have the opposite behavior."},{"Start":"04:19.595 ","End":"04:23.420","Text":"Anions are always larger than their parent atom,"},{"Start":"04:23.420 ","End":"04:26.990","Text":"whereas cations are always smaller than their parent atom."},{"Start":"04:26.990 ","End":"04:29.045","Text":"Here\u0027s some examples."},{"Start":"04:29.045 ","End":"04:33.920","Text":"Chlorine has an atomic radius of 99,"},{"Start":"04:33.920 ","End":"04:37.565","Text":"whereas chlorine minus is 181."},{"Start":"04:37.565 ","End":"04:40.340","Text":"Much larger than chlorine itself."},{"Start":"04:40.340 ","End":"04:43.325","Text":"Oxygen has a radius of 66,"},{"Start":"04:43.325 ","End":"04:47.850","Text":"but the oxygen 2 minus ion has a radius of 140,"},{"Start":"04:47.850 ","End":"04:50.160","Text":"so it\u0027s much larger than oxygen."},{"Start":"04:50.160 ","End":"04:53.220","Text":"Nitrogen 3 minus has a radius of 171"},{"Start":"04:53.220 ","End":"04:58.280","Text":"compared to the radius of nitrogen itself, which is just 75."},{"Start":"04:58.280 ","End":"05:02.810","Text":"The anion is much larger than the parent atom."},{"Start":"05:02.810 ","End":"05:06.080","Text":"Now, what are the trends?"},{"Start":"05:06.080 ","End":"05:15.620","Text":"We can see that the anions become larger as we go from right to left."},{"Start":"05:15.620 ","End":"05:20.665","Text":"In other words, becomes smaller as we go from left to right."},{"Start":"05:20.665 ","End":"05:25.340","Text":"This really only refers to the top part"},{"Start":"05:25.340 ","End":"05:31.880","Text":"here because these are the non-metals that form anions."},{"Start":"05:31.880 ","End":"05:34.175","Text":"Let\u0027s take some examples."},{"Start":"05:34.175 ","End":"05:36.165","Text":"In the second period,"},{"Start":"05:36.165 ","End":"05:39.285","Text":"nitrogen 3 minus 171,"},{"Start":"05:39.285 ","End":"05:41.945","Text":"oxygen 2 minus 140,"},{"Start":"05:41.945 ","End":"05:44.900","Text":"and fluorine minus 133."},{"Start":"05:44.900 ","End":"05:48.425","Text":"We see as the charge becomes more negative,"},{"Start":"05:48.425 ","End":"05:51.385","Text":"the anion is larger."},{"Start":"05:51.385 ","End":"05:54.540","Text":"The 3 minus, it\u0027s 171,"},{"Start":"05:54.540 ","End":"05:58.715","Text":"2 minus 140, 1 minus 133."},{"Start":"05:58.715 ","End":"06:01.325","Text":"Here\u0027s a group, group 17."},{"Start":"06:01.325 ","End":"06:06.785","Text":"Fluorine minus is 133 chlorine minus 181,"},{"Start":"06:06.785 ","End":"06:11.120","Text":"bromine minus 196, and iodine minus 220."},{"Start":"06:11.120 ","End":"06:14.899","Text":"The same behavior as we had for the atomic radius."},{"Start":"06:14.899 ","End":"06:18.585","Text":"Now what\u0027s an isoelectronic species?"},{"Start":"06:18.585 ","End":"06:24.770","Text":"Atoms and ions with the same number of electrons are called isoelectronic."},{"Start":"06:24.770 ","End":"06:27.710","Text":"They all have the same electron configuration,"},{"Start":"06:27.710 ","End":"06:32.165","Text":"but different nuclear charges leading to different radii."},{"Start":"06:32.165 ","End":"06:34.309","Text":"Let\u0027s consider an example."},{"Start":"06:34.309 ","End":"06:41.555","Text":"Cl minus K plus and magnesium 2 plus all have the same electron configuration,"},{"Start":"06:41.555 ","End":"06:45.235","Text":"the older the same electron configuration as argon."},{"Start":"06:45.235 ","End":"06:49.595","Text":"They all have the identical number of electrons."},{"Start":"06:49.595 ","End":"06:55.970","Text":"However, the nuclear charges are 17 for chlorine, 19 for potassium,"},{"Start":"06:55.970 ","End":"06:57.845","Text":"and 20 for magnesium,"},{"Start":"06:57.845 ","End":"07:03.740","Text":"so the one with the highest charge will be the smallest."},{"Start":"07:03.740 ","End":"07:07.325","Text":"We have Cl minus bigger than K plus,"},{"Start":"07:07.325 ","End":"07:10.595","Text":"which is bigger than magnesium 2 plus."},{"Start":"07:10.595 ","End":"07:15.900","Text":"This is called an isoelectronic series."},{"Start":"07:22.180 ","End":"07:27.420","Text":"In this video, we learned about ionic radii."}],"ID":21059},{"Watched":false,"Name":"Exercise 4","Duration":"3m 28s","ChapterTopicVideoID":22997,"CourseChapterTopicPlaylistID":90861,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.220","Text":"Hi, we\u0027re going to solve the following exercise."},{"Start":"00:02.220 ","End":"00:04.605","Text":"Indicate the atom or ion with the larger size."},{"Start":"00:04.605 ","End":"00:05.790","Text":"We\u0027re going to take a look at a."},{"Start":"00:05.790 ","End":"00:09.879","Text":"In a, we have the potassium atom or the potassium cation."},{"Start":"00:09.879 ","End":"00:13.695","Text":"Now since cations are always smaller than their parent atom,"},{"Start":"00:13.695 ","End":"00:17.865","Text":"the potassium atom is larger than the potassium cation,"},{"Start":"00:17.865 ","End":"00:20.535","Text":"so our answer for a is potassium."},{"Start":"00:20.535 ","End":"00:22.815","Text":"Now we\u0027re going to take a look at b."},{"Start":"00:22.815 ","End":"00:26.055","Text":"In b we have chlorine or the chloride anion."},{"Start":"00:26.055 ","End":"00:28.980","Text":"Now anions are always larger than their parent atoms, therefore,"},{"Start":"00:28.980 ","End":"00:34.035","Text":"in this case the chloride anion is the larger of the two."},{"Start":"00:34.035 ","End":"00:41.565","Text":"Now we\u0027re going on to c. In c we have the potassium cation or the calcium cation."},{"Start":"00:41.565 ","End":"00:43.310","Text":"Now, if you look at the periodic table,"},{"Start":"00:43.310 ","End":"00:46.475","Text":"you will see that the potassium cation and the calcium cation have"},{"Start":"00:46.475 ","End":"00:49.940","Text":"the same electron configuration as the noble gas argon,"},{"Start":"00:49.940 ","End":"00:52.100","Text":"and they have the same number of electrons,"},{"Start":"00:52.100 ","End":"00:53.960","Text":"meaning they are isoelectronic."},{"Start":"00:53.960 ","End":"00:55.760","Text":"In isoelectronic ions,"},{"Start":"00:55.760 ","End":"00:57.380","Text":"in order to check which is larger,"},{"Start":"00:57.380 ","End":"00:59.105","Text":"we need to look at the nuclear charge."},{"Start":"00:59.105 ","End":"01:04.130","Text":"If we look at the potassium cation and the calcium cation,"},{"Start":"01:04.130 ","End":"01:10.065","Text":"you will see that the nuclear charge for the potassium cation is 19, because that =19."},{"Start":"01:10.065 ","End":"01:15.290","Text":"The nuclear charge for the calcium cation is 20, because that =20."},{"Start":"01:15.290 ","End":"01:20.040","Text":"Now, the nuclear charge is larger for the calcium cation,"},{"Start":"01:20.040 ","End":"01:25.670","Text":"meaning the calcium cation is smaller because the higher the nuclear charge,"},{"Start":"01:25.670 ","End":"01:28.205","Text":"the smaller the ionic radius."},{"Start":"01:28.205 ","End":"01:32.344","Text":"In this case, the potassium cation is going to be the larger cation."},{"Start":"01:32.344 ","End":"01:34.940","Text":"Now we\u0027re going to go onto d. In d,"},{"Start":"01:34.940 ","End":"01:38.870","Text":"we have the bromide anion or the selenide anion."},{"Start":"01:38.870 ","End":"01:43.400","Text":"Again, the bromide and the selenide anions are isoelectronic,"},{"Start":"01:43.400 ","End":"01:46.430","Text":"meaning they have the same number of electrons and they both"},{"Start":"01:46.430 ","End":"01:49.870","Text":"have the same electron configuration as krypton, the noble gas."},{"Start":"01:49.870 ","End":"01:51.200","Text":"In this case again,"},{"Start":"01:51.200 ","End":"01:52.820","Text":"we have to look at the nuclear charge."},{"Start":"01:52.820 ","End":"01:58.345","Text":"The nuclear charge of the bromide anion = 35,"},{"Start":"01:58.345 ","End":"02:03.780","Text":"and the nuclear charge of the selenide anion = 34."},{"Start":"02:03.780 ","End":"02:09.820","Text":"Again, the ion with the higher nuclear charge has a smaller radius,"},{"Start":"02:09.820 ","End":"02:13.120","Text":"so the bromide anion has a smaller radius,"},{"Start":"02:13.120 ","End":"02:17.215","Text":"therefore the larger radius is the selenide anion."},{"Start":"02:17.215 ","End":"02:19.390","Text":"Now we\u0027re going to go on to e. In e,"},{"Start":"02:19.390 ","End":"02:22.840","Text":"we have the bromide anion and the rubidium cation."},{"Start":"02:22.840 ","End":"02:24.970","Text":"Again, these two are isoelectronic,"},{"Start":"02:24.970 ","End":"02:27.580","Text":"meaning they have the same number of electrons and again,"},{"Start":"02:27.580 ","End":"02:31.420","Text":"they have the same electron configuration as the noble gas krypton."},{"Start":"02:31.420 ","End":"02:33.969","Text":"If we look at the bromide anion,"},{"Start":"02:33.969 ","End":"02:37.135","Text":"we will see that the nuclear charge is 35."},{"Start":"02:37.135 ","End":"02:40.685","Text":"Compare it to the rubidium cation,"},{"Start":"02:40.685 ","End":"02:43.890","Text":"and the nuclear charge is 37."},{"Start":"02:43.890 ","End":"02:49.055","Text":"Again, the higher nuclear charge belongs to the smaller radius."},{"Start":"02:49.055 ","End":"02:53.750","Text":"Meaning that the rubidium cation has a smaller radius,"},{"Start":"02:53.750 ","End":"02:58.430","Text":"therefore the bromide anion has a larger radius."},{"Start":"02:58.430 ","End":"03:00.200","Text":"Again, we\u0027re just going to take a look at our answers."},{"Start":"03:00.200 ","End":"03:05.990","Text":"In a, we found that the potassium atom has a larger radius,"},{"Start":"03:05.990 ","End":"03:10.880","Text":"b we found that the chloride anion is larger and c,"},{"Start":"03:10.880 ","End":"03:13.520","Text":"we found that the potassium cation is larger."},{"Start":"03:13.520 ","End":"03:21.090","Text":"In d, the selenide anion was the ion with the larger size and in e,"},{"Start":"03:21.670 ","End":"03:25.730","Text":"the bromide anion has a larger size."},{"Start":"03:25.730 ","End":"03:27.350","Text":"These are our final answers."},{"Start":"03:27.350 ","End":"03:29.790","Text":"Thank you very much for watching."}],"ID":23847},{"Watched":false,"Name":"Exercise 5","Duration":"3m 33s","ChapterTopicVideoID":22998,"CourseChapterTopicPlaylistID":90861,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.550","Text":"Hi, we\u0027re going to solve the following exercise."},{"Start":"00:03.550 ","End":"00:06.850","Text":"Give 1 example of an isoelectronic pair of: a,"},{"Start":"00:06.850 ","End":"00:08.950","Text":"2 different cations, b,"},{"Start":"00:08.950 ","End":"00:10.415","Text":"2 different anions,"},{"Start":"00:10.415 ","End":"00:13.030","Text":"and c, a cation and an anion."},{"Start":"00:13.030 ","End":"00:17.650","Text":"First I want to remind you that isoelectronic species are atoms or ions"},{"Start":"00:17.650 ","End":"00:22.360","Text":"with the same number of electrons and they also have the same electron configuration."},{"Start":"00:22.360 ","End":"00:25.420","Text":"For a, we want 2 different cations."},{"Start":"00:25.420 ","End":"00:28.105","Text":"If you look at your periodic table,"},{"Start":"00:28.105 ","End":"00:35.640","Text":"you will see that the sodium cation and the magnesium cation,"},{"Start":"00:35.640 ","End":"00:43.490","Text":"for example, have the same electron configuration as the noble gas neon."},{"Start":"00:44.750 ","End":"00:49.540","Text":"You were asked to give 1 example of an isoelectronic pair of 2 different cations,"},{"Start":"00:49.540 ","End":"00:51.070","Text":"but I\u0027ll give you another example."},{"Start":"00:51.070 ","End":"00:58.400","Text":"For example, we can also take the potassium cation and the calcium cation."},{"Start":"00:58.400 ","End":"01:02.050","Text":"These have the same electron configuration and the same number of"},{"Start":"01:02.050 ","End":"01:05.500","Text":"electrons as the noble gas argon."},{"Start":"01:05.500 ","End":"01:10.525","Text":"That\u0027s another example of 2 cations which are isoelectronic."},{"Start":"01:10.525 ","End":"01:15.070","Text":"Now it\u0027s also important to note that an isoelectronic pair of cations don\u0027t"},{"Start":"01:15.070 ","End":"01:19.825","Text":"have to have the same electron configuration as a noble gas as in these 2 examples."},{"Start":"01:19.825 ","End":"01:30.460","Text":"For example, the copper cation and the zinc cation are also isoelectronic cations,"},{"Start":"01:30.460 ","End":"01:37.460","Text":"and they have the same electron configuration as the argon 3d^10."},{"Start":"01:37.460 ","End":"01:40.645","Text":"There\u0027s the argon and another 10 electrons in their d-orbital."},{"Start":"01:40.645 ","End":"01:43.660","Text":"That\u0027s another example of 2 cations which"},{"Start":"01:43.660 ","End":"01:46.360","Text":"are an isoelectronic pair. Now we\u0027ll go on to b."},{"Start":"01:46.360 ","End":"01:52.315","Text":"In b, we\u0027re asked to find 2 different anions which are isoelectronic."},{"Start":"01:52.315 ","End":"01:54.715","Text":"Again, look at your periodic table."},{"Start":"01:54.715 ","End":"01:56.380","Text":"These can be, for example,"},{"Start":"01:56.380 ","End":"02:01.530","Text":"the bromide anion and the selenide anion."},{"Start":"02:01.530 ","End":"02:04.630","Text":"These have the same electron configuration and"},{"Start":"02:04.630 ","End":"02:07.980","Text":"the same number of electrons as the krypton gas,"},{"Start":"02:07.980 ","End":"02:14.663","Text":"or for example the chloride anion and the sulfur anion,"},{"Start":"02:14.663 ","End":"02:18.695","Text":"or for example the chloride anion and the sulfide anion."},{"Start":"02:18.695 ","End":"02:22.375","Text":"These have the same electron configuration as the argon gas."},{"Start":"02:22.375 ","End":"02:27.095","Text":"This is an example of 2 different anions which are isoelectronic."},{"Start":"02:27.095 ","End":"02:30.290","Text":"Now in c, we\u0027re asked to find a cation and an anion."},{"Start":"02:30.290 ","End":"02:32.750","Text":"These can be taken from the anions that we have"},{"Start":"02:32.750 ","End":"02:37.640","Text":"previously given in the other question, and the cations."},{"Start":"02:37.640 ","End":"02:42.710","Text":"For example, the potassium cation and"},{"Start":"02:42.710 ","End":"02:45.320","Text":"the chloride anion both give us"},{"Start":"02:45.320 ","End":"02:48.755","Text":"the same electron configuration and number of electrons as argon."},{"Start":"02:48.755 ","End":"02:54.180","Text":"Another example is the rubidium cation and the bromide anion."},{"Start":"02:54.180 ","End":"02:58.805","Text":"These give us the same electron configuration as krypton."},{"Start":"02:58.805 ","End":"03:04.160","Text":"Those are 2 examples of a cation and anion which are isoelectronic."},{"Start":"03:04.160 ","End":"03:05.780","Text":"Again, in a,"},{"Start":"03:05.780 ","End":"03:08.794","Text":"1 example of an isoelectronic pair of cations"},{"Start":"03:08.794 ","End":"03:12.320","Text":"is the sodium cation and the magnesium cation."},{"Start":"03:12.320 ","End":"03:16.100","Text":"1 example in b of an isoelectronic pair of"},{"Start":"03:16.100 ","End":"03:20.450","Text":"anions is the bromide anion and the selenide anion."},{"Start":"03:20.450 ","End":"03:26.390","Text":"Then c, 1 example of a cation and an anion which are isoelectronic,"},{"Start":"03:26.390 ","End":"03:29.870","Text":"is the potassium cation and the chloride anion."},{"Start":"03:29.870 ","End":"03:31.790","Text":"These are our final answers."},{"Start":"03:31.790 ","End":"03:34.410","Text":"Thank you very much for watching."}],"ID":23848}],"Thumbnail":null,"ID":90861},{"Name":"Losing or Gaining Electrons","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Ionization Energy","Duration":"8m 48s","ChapterTopicVideoID":20267,"CourseChapterTopicPlaylistID":90862,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:01.560","Text":"In previous videos,"},{"Start":"00:01.560 ","End":"00:04.575","Text":"we talked about the atomic and ionic radius."},{"Start":"00:04.575 ","End":"00:09.150","Text":"In this video, we\u0027ll learn about the ionization energy."},{"Start":"00:09.150 ","End":"00:11.925","Text":"What\u0027s the ionization energy?"},{"Start":"00:11.925 ","End":"00:15.510","Text":"The ionization energy is the minimum energy required to"},{"Start":"00:15.510 ","End":"00:19.245","Text":"remove an electron from an atom in the gas phase."},{"Start":"00:19.245 ","End":"00:23.505","Text":"Minimum means that it doesn\u0027t have any kinetic energy."},{"Start":"00:23.505 ","End":"00:25.260","Text":"To go from X,"},{"Start":"00:25.260 ","End":"00:27.420","Text":"which has some element in the gas phase,"},{"Start":"00:27.420 ","End":"00:31.666","Text":"to X plus the gas phase, releasing electron."},{"Start":"00:31.666 ","End":"00:36.765","Text":"This is called the ionization energy and we\u0027re going to write it as I."},{"Start":"00:36.765 ","End":"00:39.405","Text":"Some people use E_i(X),"},{"Start":"00:39.405 ","End":"00:42.030","Text":"but we\u0027re just going to use I."},{"Start":"00:42.030 ","End":"00:46.495","Text":"We\u0027re going to consider 3 examples: hydrogen, magnesium, and aluminum."},{"Start":"00:46.495 ","End":"00:49.975","Text":"But we\u0027ve already talked about hydrogen in the previous video."},{"Start":"00:49.975 ","End":"00:52.165","Text":"Let\u0027s recall hydrogen."},{"Start":"00:52.165 ","End":"00:54.970","Text":"To go from hydrogen to hydrogen plus,"},{"Start":"00:54.970 ","End":"00:58.420","Text":"taking out electron, that\u0027s I_1,"},{"Start":"00:58.420 ","End":"01:04.575","Text":"there\u0027s the difference in energy between the highest energy state n equal to infinity,"},{"Start":"01:04.575 ","End":"01:07.585","Text":"and the ground energy state n=1."},{"Start":"01:07.585 ","End":"01:11.030","Text":"There\u0027s difference in n=1,"},{"Start":"01:11.030 ","End":"01:14.200","Text":"to n equal to infinity,"},{"Start":"01:14.360 ","End":"01:22.825","Text":"and we saw in previous video that that energy is 100,312 kilojoules per mole."},{"Start":"01:22.825 ","End":"01:25.800","Text":"Now let\u0027s look at magnesium."},{"Start":"01:25.800 ","End":"01:29.415","Text":"To go from magnesium to magnesium plus that\u0027s I_1,"},{"Start":"01:29.415 ","End":"01:32.430","Text":"is 738 kilojoules per mole."},{"Start":"01:32.430 ","End":"01:37.260","Text":"To go from magnesium plus to magnesium 2 plus, that\u0027s I_2,"},{"Start":"01:37.260 ","End":"01:40.985","Text":"is 1,451 kilojoules per mole,"},{"Start":"01:40.985 ","End":"01:43.090","Text":"approximately twice as much."},{"Start":"01:43.090 ","End":"01:48.075","Text":"To go from magnesium 2 plus to magnesium 3 plus, that\u0027s I_3,"},{"Start":"01:48.075 ","End":"01:54.740","Text":"is much, much greater than to go from the 1st electron or taking out the 2nd electron."},{"Start":"01:54.740 ","End":"01:59.615","Text":"I_3 is 7,733 kilojoules per mole."},{"Start":"01:59.615 ","End":"02:01.290","Text":"How can we explain this?"},{"Start":"02:01.290 ","End":"02:05.650","Text":"We need to look at the electron configurations."},{"Start":"02:05.650 ","End":"02:09.420","Text":"Magnesium, it has 2 electrons in the 3s,"},{"Start":"02:09.420 ","End":"02:12.840","Text":"magnesium plus, has 1 electron and 3s."},{"Start":"02:12.840 ","End":"02:15.310","Text":"We\u0027ve taken out 1 electron from 3s."},{"Start":"02:15.310 ","End":"02:18.850","Text":"Magnesium 2 plus has no electrons in 3s,"},{"Start":"02:18.850 ","End":"02:22.480","Text":"so we\u0027ve taken out all the electrons in the valence shell,"},{"Start":"02:22.480 ","End":"02:24.530","Text":"and we\u0027re left with neon."},{"Start":"02:24.530 ","End":"02:28.820","Text":"Now to take out another electron means we have to take it out from neon,"},{"Start":"02:28.820 ","End":"02:31.795","Text":"which is closed shell."},{"Start":"02:31.795 ","End":"02:36.125","Text":"To have a closed shell to take out another electron,"},{"Start":"02:36.125 ","End":"02:39.590","Text":"and so that costs a ginormous amount of energy."},{"Start":"02:39.590 ","End":"02:43.380","Text":"We\u0027re taking out electrons from a closed shell."},{"Start":"02:43.750 ","End":"02:47.150","Text":"That would leave us with helium,"},{"Start":"02:47.150 ","End":"02:48.995","Text":"the previous noble gas,"},{"Start":"02:48.995 ","End":"02:52.730","Text":"2 electrons and 2s and 5 electrons in 2p."},{"Start":"02:52.730 ","End":"02:54.815","Text":"Now let\u0027s look at aluminum."},{"Start":"02:54.815 ","End":"03:00.500","Text":"The 1st ionization potential is 578 kilojoules per mole."},{"Start":"03:00.500 ","End":"03:03.755","Text":"The 2nd is 1,817,"},{"Start":"03:03.755 ","End":"03:05.935","Text":"about 3 times as higher,"},{"Start":"03:05.935 ","End":"03:10.275","Text":"and the 3rd one is 2,745."},{"Start":"03:10.275 ","End":"03:12.360","Text":"It\u0027s much higher than I_2,"},{"Start":"03:12.360 ","End":"03:15.010","Text":"but not enormously so 2,745."},{"Start":"03:15.770 ","End":"03:19.580","Text":"Let\u0027s look at the electron configurations."},{"Start":"03:19.580 ","End":"03:24.610","Text":"Aluminum has 2 electrons and 3s and 1 electron and 3p."},{"Start":"03:24.610 ","End":"03:27.415","Text":"The 1st election we take out is from 3p,"},{"Start":"03:27.415 ","End":"03:29.885","Text":"so we\u0027re left with 2 electrons and 3s."},{"Start":"03:29.885 ","End":"03:33.020","Text":"Then we have to take out another electron,"},{"Start":"03:33.020 ","End":"03:36.110","Text":"this time from a positively charged cation,"},{"Start":"03:36.110 ","End":"03:38.000","Text":"so it\u0027s a bit more difficult,"},{"Start":"03:38.000 ","End":"03:40.455","Text":"and we have to take it out from the 3s,"},{"Start":"03:40.455 ","End":"03:43.165","Text":"so we\u0027re left with just 1 electron and 3s."},{"Start":"03:43.165 ","End":"03:47.150","Text":"Now we have to take out electron from the 3s,"},{"Start":"03:47.150 ","End":"03:51.245","Text":"from cation with a positive charge of 2."},{"Start":"03:51.245 ","End":"03:53.180","Text":"That\u0027s a bit more difficult,"},{"Start":"03:53.180 ","End":"03:55.565","Text":"and that gives us aluminum 3 plus,"},{"Start":"03:55.565 ","End":"03:58.790","Text":"now in a closed shell configuration."},{"Start":"03:58.790 ","End":"04:03.870","Text":"That\u0027s the reason that I_3 is bigger than I_2,"},{"Start":"04:04.280 ","End":"04:07.050","Text":"bigger than I_1,"},{"Start":"04:07.050 ","End":"04:09.120","Text":"but not enormously so,"},{"Start":"04:09.120 ","End":"04:12.210","Text":"like the previous case of magnesium."},{"Start":"04:12.210 ","End":"04:20.210","Text":"We can summarize that by saying that the I_3 from magnesium is 3 times I_3 for aluminum."},{"Start":"04:20.210 ","End":"04:24.310","Text":"Now, let us look at the trends in the main group elements."},{"Start":"04:24.310 ","End":"04:28.835","Text":"The ionization energy generally increases across a period."},{"Start":"04:28.835 ","End":"04:31.280","Text":"Here it is increasing across a period."},{"Start":"04:31.280 ","End":"04:34.220","Text":"This is the ionization energy,"},{"Start":"04:34.220 ","End":"04:38.945","Text":"and that\u0027s the same behavior as that of the effective nuclear charge."},{"Start":"04:38.945 ","End":"04:41.810","Text":"The green is z effective."},{"Start":"04:41.810 ","End":"04:46.550","Text":"Of course it\u0027s the opposite behavior from the atomic radius,"},{"Start":"04:46.550 ","End":"04:48.410","Text":"which I\u0027ve done in red here,"},{"Start":"04:48.410 ","End":"04:50.440","Text":"so that\u0027s the radius."},{"Start":"04:50.440 ","End":"04:53.720","Text":"Down the group, the ionization energy generally"},{"Start":"04:53.720 ","End":"04:58.100","Text":"decreases down a group as the atomic radius increases."},{"Start":"04:58.100 ","End":"05:01.510","Text":"Here is our ionization energy,"},{"Start":"05:01.510 ","End":"05:03.870","Text":"highest at the top,"},{"Start":"05:03.870 ","End":"05:06.635","Text":"compared to the atomic radius,"},{"Start":"05:06.635 ","End":"05:09.125","Text":"which is highest at the bottom."},{"Start":"05:09.125 ","End":"05:12.845","Text":"Of course, there are occasional exceptions."},{"Start":"05:12.845 ","End":"05:19.705","Text":"For example, oxygen has a slightly lower ionization energy than nitrogen."},{"Start":"05:19.705 ","End":"05:22.160","Text":"What\u0027s the reason for this?"},{"Start":"05:22.160 ","End":"05:27.800","Text":"Nitrogen has configuration of 2p^3,"},{"Start":"05:27.800 ","End":"05:30.235","Text":"it has 3 electrons and 2p,"},{"Start":"05:30.235 ","End":"05:34.535","Text":"whereas oxygen has 4 electrons and 2p."},{"Start":"05:34.535 ","End":"05:38.980","Text":"In nitrogen, each electron and 2p,"},{"Start":"05:38.980 ","End":"05:42.950","Text":"can be in a different orbital, whereas an oxygen,"},{"Start":"05:42.950 ","End":"05:46.730","Text":"one of the orbitals contains 2 electrons,"},{"Start":"05:46.730 ","End":"05:49.500","Text":"which can repel each other,"},{"Start":"05:49.870 ","End":"05:54.840","Text":"giving a little extra kick for the electron to leave,"},{"Start":"05:54.840 ","End":"06:00.595","Text":"and that\u0027s the reason that oxygen is slightly lower ionization energy than nitrogen."},{"Start":"06:00.595 ","End":"06:06.005","Text":"Now, the highest values of the ionization energy on the top right-hand corner,"},{"Start":"06:06.005 ","End":"06:09.410","Text":"Group 18, I\u0027ve indicated it here in red."},{"Start":"06:09.410 ","End":"06:12.155","Text":"Helium is 2,370,"},{"Start":"06:12.155 ","End":"06:16.440","Text":"and neon, 2,080 kilojoules per mole."},{"Start":"06:16.440 ","End":"06:20.570","Text":"The very high ionization to the top right-hand corner."},{"Start":"06:20.570 ","End":"06:24.890","Text":"These are rare gases or noble gases."},{"Start":"06:24.890 ","End":"06:29.630","Text":"The elements with the highest ionization energies are usually nonmetals."},{"Start":"06:29.630 ","End":"06:34.585","Text":"Now, the lowest values of ionization energy in the bottom left-hand corner."},{"Start":"06:34.585 ","End":"06:36.135","Text":"Here\u0027s Group 1,"},{"Start":"06:36.135 ","End":"06:38.250","Text":"I\u0027ve indicated in blue,"},{"Start":"06:38.250 ","End":"06:44.580","Text":"and we have rubidium 402 and cesium 376 kilojoules per mole."},{"Start":"06:44.580 ","End":"06:49.880","Text":"These are much, much lower ionization energies than those of the nonmetals."},{"Start":"06:49.880 ","End":"06:52.310","Text":"Let\u0027s say a few words about metals."},{"Start":"06:52.310 ","End":"06:53.750","Text":"First of core,"},{"Start":"06:53.750 ","End":"06:57.050","Text":"the elements with the lowest ionization energies are metals,"},{"Start":"06:57.050 ","End":"07:00.190","Text":"and tend to form positive ions."},{"Start":"07:00.190 ","End":"07:04.280","Text":"Now, metals themselves consists of an array of cations in"},{"Start":"07:04.280 ","End":"07:08.595","Text":"a sea of electrons that move easily and conduct electricity."},{"Start":"07:08.595 ","End":"07:12.875","Text":"We have to release these electrons from the atoms."},{"Start":"07:12.875 ","End":"07:23.000","Text":"That means that only substances that have a very low ionization energy can be metals,"},{"Start":"07:23.000 ","End":"07:30.660","Text":"because we have all these little cations in a sea of electrons."},{"Start":"07:31.610 ","End":"07:36.935","Text":"Now, let\u0027s look at the behavior of the metallic character."},{"Start":"07:36.935 ","End":"07:42.605","Text":"This is an example of behavior which changes diagonally."},{"Start":"07:42.605 ","End":"07:46.940","Text":"Previously we had behavior that changed along a period"},{"Start":"07:46.940 ","End":"07:51.595","Text":"or changed down a group here, there\u0027s diagonal behavior."},{"Start":"07:51.595 ","End":"07:54.345","Text":"We can distinguish which is which,"},{"Start":"07:54.345 ","End":"07:58.395","Text":"because the red arrow on the top,"},{"Start":"07:58.395 ","End":"08:03.720","Text":"the grid is pointing towards the metals."},{"Start":"08:03.720 ","End":"08:07.690","Text":"This is increasing metallic character."},{"Start":"08:11.900 ","End":"08:16.355","Text":"Whereas the lower arrow is pointing towards the nonmetals,"},{"Start":"08:16.355 ","End":"08:19.620","Text":"so that\u0027s increasing"},{"Start":"08:21.070 ","End":"08:32.520","Text":"non-metallic character."},{"Start":"08:33.350 ","End":"08:37.560","Text":"Here it\u0027s summarized. Metallic character increases diagonally,"},{"Start":"08:37.560 ","End":"08:42.215","Text":"non-metallic character decreases diagonally in the opposite direction."},{"Start":"08:42.215 ","End":"08:47.970","Text":"In this video, we talked about ionization energy."}],"ID":21060},{"Watched":false,"Name":"Exercise 1","Duration":"3m 25s","ChapterTopicVideoID":22999,"CourseChapterTopicPlaylistID":90862,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.075","Text":"Hi. We\u0027re going to solve the following exercise."},{"Start":"00:03.075 ","End":"00:07.380","Text":"Arrange the following in order of decreasing ionization energy: germanium,"},{"Start":"00:07.380 ","End":"00:10.890","Text":"francium, barium, nitrogen, and tin."},{"Start":"00:10.890 ","End":"00:13.230","Text":"First of all, we\u0027re going to look at the general trend in"},{"Start":"00:13.230 ","End":"00:16.545","Text":"our periodic table of what happens with ionization energy."},{"Start":"00:16.545 ","End":"00:19.740","Text":"The general trend of the ionization energy is actually"},{"Start":"00:19.740 ","End":"00:24.570","Text":"the opposite of the general trend for the atomic radius."},{"Start":"00:24.570 ","End":"00:28.440","Text":"In this case, as we go from left to right in a period,"},{"Start":"00:28.440 ","End":"00:32.440","Text":"the ionization energy increases."},{"Start":"00:33.260 ","End":"00:38.685","Text":"As we go from top to bottom down a group in the periodic table,"},{"Start":"00:38.685 ","End":"00:43.060","Text":"the ionization energy decreases."},{"Start":"00:46.280 ","End":"00:49.060","Text":"Now this is of course the general trend."},{"Start":"00:49.060 ","End":"00:50.815","Text":"There are exceptions to the rule."},{"Start":"00:50.815 ","End":"00:54.189","Text":"Now if we look at the atoms that we are given here in the question,"},{"Start":"00:54.189 ","End":"00:57.310","Text":"we have germanium and if you will look at the periodic table,"},{"Start":"00:57.310 ","End":"01:02.635","Text":"you will see that germanium is in group 14 and period 4."},{"Start":"01:02.635 ","End":"01:05.350","Text":"We\u0027re also given francium."},{"Start":"01:05.350 ","End":"01:11.650","Text":"Francium is in group 2 and period 7."},{"Start":"01:11.650 ","End":"01:19.220","Text":"Barium is in group 2, period 6."},{"Start":"01:19.860 ","End":"01:27.670","Text":"Nitrogen is in group 15 and period 2 and"},{"Start":"01:27.670 ","End":"01:35.830","Text":"tin is found in group 14, period 5."},{"Start":"01:35.830 ","End":"01:40.269","Text":"Now again, if we look at the general trend of the ionization energy,"},{"Start":"01:40.269 ","End":"01:44.200","Text":"and we want to find the largest ionization energy."},{"Start":"01:44.200 ","End":"01:49.885","Text":"The largest will be most to the right and also most to the top."},{"Start":"01:49.885 ","End":"01:53.800","Text":"Since again, the ionization energy increases as we go from left to right in"},{"Start":"01:53.800 ","End":"01:59.005","Text":"a period and from bottom to top in a group, it also increases."},{"Start":"01:59.005 ","End":"02:01.930","Text":"Again, the atom which is most to the top"},{"Start":"02:01.930 ","End":"02:05.305","Text":"and to the right is going to have the largest ionization energy."},{"Start":"02:05.305 ","End":"02:08.435","Text":"If we compare all of these in our case,"},{"Start":"02:08.435 ","End":"02:15.860","Text":"the nitrogen is also most of the right since it\u0027s in group 15 and all the rest are in"},{"Start":"02:15.860 ","End":"02:19.670","Text":"lower groups and it\u0027s also most to the top since it\u0027s in"},{"Start":"02:19.670 ","End":"02:25.295","Text":"period 2 and that\u0027s the highest period from all the atoms we\u0027re given."},{"Start":"02:25.295 ","End":"02:29.585","Text":"The nitrogen is going to have the largest ionization energy."},{"Start":"02:29.585 ","End":"02:32.915","Text":"Next we have germanium and tin,"},{"Start":"02:32.915 ","End":"02:36.200","Text":"which are in the same group but if we look at the periods,"},{"Start":"02:36.200 ","End":"02:42.050","Text":"we can see that germanium is higher up compared to the tin,"},{"Start":"02:42.050 ","End":"02:47.680","Text":"and therefore germanium is going to be second and tin is going to be third."},{"Start":"02:47.680 ","End":"02:51.410","Text":"Because again, they\u0027re in period 4 and 5."},{"Start":"02:51.410 ","End":"02:54.950","Text":"Now we\u0027re going on and we have our barium and"},{"Start":"02:54.950 ","End":"02:57.420","Text":"our francium and if we compare"},{"Start":"02:57.420 ","End":"03:00.725","Text":"the barium and the francium we can see that there are in the same group."},{"Start":"03:00.725 ","End":"03:05.210","Text":"However, the barium is higher up since it\u0027s in period 6 compared to the francium,"},{"Start":"03:05.210 ","End":"03:06.875","Text":"which is in period 7."},{"Start":"03:06.875 ","End":"03:14.419","Text":"Therefore, the barium is going to have a larger ionization energy than the francium."},{"Start":"03:14.419 ","End":"03:19.055","Text":"So again, the nitrogen has the largest ionization energy than the germanium,"},{"Start":"03:19.055 ","End":"03:22.430","Text":"tin, barium and francium."},{"Start":"03:22.430 ","End":"03:23.900","Text":"That is our final answer."},{"Start":"03:23.900 ","End":"03:26.520","Text":"Thank you very much for watching."}],"ID":23840},{"Watched":false,"Name":"Exercise 2","Duration":"2m 33s","ChapterTopicVideoID":23000,"CourseChapterTopicPlaylistID":90862,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.595","Text":"Hi. We\u0027re going to solve the following exercise."},{"Start":"00:02.595 ","End":"00:04.950","Text":"How much energy must be absorbed to convert"},{"Start":"00:04.950 ","End":"00:09.300","Text":"200 milligrams of magnesium to the magnesium cation?"},{"Start":"00:09.300 ","End":"00:15.870","Text":"The first ionization energy of magnesium equals 737.7 kilojoules per mole."},{"Start":"00:15.870 ","End":"00:17.970","Text":"What we\u0027re going to do is first of all,"},{"Start":"00:17.970 ","End":"00:21.660","Text":"calculate the number of moles of the magnesium,"},{"Start":"00:21.660 ","End":"00:26.940","Text":"and then we will calculate the energy which needs to be absorbed."},{"Start":"00:26.940 ","End":"00:31.590","Text":"Remember that the number of moles equals the mass divided by the molar mass."},{"Start":"00:31.590 ","End":"00:36.780","Text":"Again, the number of moles equals the mass divided by the molar mass."},{"Start":"00:36.780 ","End":"00:45.755","Text":"The mass in our case is 200 milligrams divided by the molar mass of magnesium,"},{"Start":"00:45.755 ","End":"00:51.450","Text":"which is 24.31 grams per mole."},{"Start":"00:51.460 ","End":"00:54.830","Text":"Since we have milligrams and grams,"},{"Start":"00:54.830 ","End":"00:57.140","Text":"we\u0027re going to use a conversion factor."},{"Start":"00:57.140 ","End":"00:59.330","Text":"We\u0027re going to convert our milligrams to grams."},{"Start":"00:59.330 ","End":"01:05.500","Text":"We\u0027re going to multiply this by 1 gram per 1,000 milligrams."},{"Start":"01:05.500 ","End":"01:09.255","Text":"The milligrams is going to cancel out."},{"Start":"01:09.255 ","End":"01:19.110","Text":"This equals 8.23 times 10^-3 moles of magnesium."},{"Start":"01:19.110 ","End":"01:22.255","Text":"Now we know the number of moles of magnesium,"},{"Start":"01:22.255 ","End":"01:26.225","Text":"and we also know that the first ionization energy of magnesium"},{"Start":"01:26.225 ","End":"01:31.920","Text":"equals 737.7 kilojoules per mole."},{"Start":"01:34.580 ","End":"01:37.835","Text":"To calculate the energy which must be absorbed,"},{"Start":"01:37.835 ","End":"01:40.310","Text":"it just equals the number of moles,"},{"Start":"01:40.310 ","End":"01:43.145","Text":"which we calculated a magnesium of course,"},{"Start":"01:43.145 ","End":"01:49.775","Text":"times the first ionization energy of magnesium,"},{"Start":"01:49.775 ","End":"01:53.465","Text":"since we\u0027re going from magnesium to magnesium plus."},{"Start":"01:53.465 ","End":"01:59.930","Text":"The number of moles of magnesium is 8.23 times 10 to the negative 3 mole,"},{"Start":"01:59.930 ","End":"02:06.320","Text":"which is what we calculated times the first ionization energy of magnesium,"},{"Start":"02:06.320 ","End":"02:13.770","Text":"which equals again 737.7 kilojoules per mole."},{"Start":"02:13.770 ","End":"02:16.080","Text":"The moles cancel out,"},{"Start":"02:16.080 ","End":"02:21.290","Text":"and our answer is 6.07 kilojoules."},{"Start":"02:21.290 ","End":"02:24.170","Text":"The energy which must be absorbed again to convert"},{"Start":"02:24.170 ","End":"02:27.994","Text":"200 milligrams of magnesium to magnesium plus equals"},{"Start":"02:27.994 ","End":"02:30.545","Text":"6.07 kilojoules."},{"Start":"02:30.545 ","End":"02:32.030","Text":"That is our final answer."},{"Start":"02:32.030 ","End":"02:34.590","Text":"Thank you very much for watching."}],"ID":23841},{"Watched":false,"Name":"Exercise 3","Duration":"2m 6s","ChapterTopicVideoID":23001,"CourseChapterTopicPlaylistID":90862,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.835","Text":"Hi, we\u0027re going to solve the following exercise."},{"Start":"00:02.835 ","End":"00:04.950","Text":"How much energy is required to remove"},{"Start":"00:04.950 ","End":"00:09.750","Text":"all the third shell electrons and 3 moles of gaseous aluminum atoms."},{"Start":"00:09.750 ","End":"00:12.150","Text":"In the third shell of aluminum,"},{"Start":"00:12.150 ","End":"00:13.695","Text":"we have 3 electrons,"},{"Start":"00:13.695 ","End":"00:17.685","Text":"2 are in the S orbital and 1 is in the P orbital."},{"Start":"00:17.685 ","End":"00:19.950","Text":"Here we know the first ionization energy,"},{"Start":"00:19.950 ","End":"00:21.330","Text":"the second ionization energy,"},{"Start":"00:21.330 ","End":"00:24.135","Text":"and the third ionization energy of aluminum."},{"Start":"00:24.135 ","End":"00:26.940","Text":"First of all, to find the energy per mole that is"},{"Start":"00:26.940 ","End":"00:29.820","Text":"required to remove all of these electrons,"},{"Start":"00:29.820 ","End":"00:32.955","Text":"we have to sum up all of our ionization energies."},{"Start":"00:32.955 ","End":"00:35.340","Text":"The ionization energy equals"},{"Start":"00:35.340 ","End":"00:40.420","Text":"the first ionization energy plus the second 1 plus the third 1."},{"Start":"00:57.770 ","End":"01:07.510","Text":"The sum of the ionization energies equals 5,139.6 kilojoules per mole."},{"Start":"01:07.510 ","End":"01:11.620","Text":"Now again, after summing up all of the ionization energies,"},{"Start":"01:11.620 ","End":"01:14.680","Text":"we found the energy which is required to remove"},{"Start":"01:14.680 ","End":"01:18.520","Text":"the third shell electrons in 1 mole of gaseous aluminum atoms,"},{"Start":"01:18.520 ","End":"01:20.680","Text":"since this is in kilojoules per mole."},{"Start":"01:20.680 ","End":"01:24.070","Text":"Since we know we have 3 moles of gaseous aluminum atoms,"},{"Start":"01:24.070 ","End":"01:28.710","Text":"we have to take this value and multiply it by 3."},{"Start":"01:28.710 ","End":"01:33.560","Text":"The energy which is required is the energy per"},{"Start":"01:33.560 ","End":"01:41.110","Text":"mole times 3 mole."},{"Start":"01:41.110 ","End":"01:51.695","Text":"The moles cancel out and this equals 15,418.8 kilojoules."},{"Start":"01:51.695 ","End":"01:53.870","Text":"Again, the amount of energy which is required to"},{"Start":"01:53.870 ","End":"01:56.210","Text":"remove all the search electrons and 3 moles of"},{"Start":"01:56.210 ","End":"02:02.900","Text":"gaseous aluminum atoms equals 15,418.8 kilojoules."},{"Start":"02:02.900 ","End":"02:04.490","Text":"That is our final answer."},{"Start":"02:04.490 ","End":"02:07.110","Text":"Thank you very much for watching."}],"ID":23842},{"Watched":false,"Name":"Exercise 4","Duration":"3m 11s","ChapterTopicVideoID":23002,"CourseChapterTopicPlaylistID":90862,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.045","Text":"Hi. We\u0027re going to solve the following exercise."},{"Start":"00:03.045 ","End":"00:06.690","Text":"How many sodium ions can be produced per kilojoule of energy"},{"Start":"00:06.690 ","End":"00:10.350","Text":"absorbed by a sample of gaseous sodium atoms?"},{"Start":"00:10.350 ","End":"00:17.490","Text":"The first ionization energy of sodium equals 495.8 kilojoules per mole."},{"Start":"00:17.490 ","End":"00:22.680","Text":"We know that the energy which is required to remove 1 electron from"},{"Start":"00:22.680 ","End":"00:29.085","Text":"a mole of gaseous sodium atoms equals 495.8 kilojoules."},{"Start":"00:29.085 ","End":"00:31.155","Text":"Again, this is per mole."},{"Start":"00:31.155 ","End":"00:34.755","Text":"Assuming that we have 1 mole of sodium atoms,"},{"Start":"00:34.755 ","End":"00:38.685","Text":"we\u0027re going to get 1 mole of sodium ions, and then 1 mole,"},{"Start":"00:38.685 ","End":"00:47.700","Text":"just want to remind you we have 6.022 times 10 to the 23 ions."},{"Start":"00:47.700 ","End":"00:49.555","Text":"In this case again,"},{"Start":"00:49.555 ","End":"00:55.430","Text":"this is Avogadro\u0027s number and this could be also atoms and molecules and so on."},{"Start":"00:55.430 ","End":"00:59.905","Text":"In our case, this is ions because we\u0027re talking about the sodium ions."},{"Start":"00:59.905 ","End":"01:06.660","Text":"I know that I have 6.022 times 10 to the 23 ions in 1 mole of sodium ions,"},{"Start":"01:06.660 ","End":"01:10.670","Text":"and I also know that the energy which is required to turn"},{"Start":"01:10.670 ","End":"01:16.180","Text":"the sodium atoms into ions is 495.8 kilojoules per mole."},{"Start":"01:16.180 ","End":"01:18.635","Text":"If I take the number of ions per mole,"},{"Start":"01:18.635 ","End":"01:27.360","Text":"which is 6.022 times 10^23 ions per mole,"},{"Start":"01:27.670 ","End":"01:34.260","Text":"and divide this by the energy per mole,"},{"Start":"01:34.260 ","End":"01:42.010","Text":"which is 495.8 kilojoules per mole."},{"Start":"01:42.820 ","End":"01:50.480","Text":"I will find the number of sodium ions which can be produced per kilojoule of energy."},{"Start":"01:50.480 ","End":"02:01.450","Text":"This equals 1.21 times 10^23 ions per kilojoule."},{"Start":"02:01.450 ","End":"02:04.130","Text":"Just a reminder, if we look at our units here,"},{"Start":"02:04.130 ","End":"02:06.690","Text":"we have ions per mole,"},{"Start":"02:09.340 ","End":"02:13.085","Text":"divided by kilojoules per mole,"},{"Start":"02:13.085 ","End":"02:16.910","Text":"which is a fraction divided by a fraction."},{"Start":"02:16.910 ","End":"02:18.995","Text":"When you divide by a fraction,"},{"Start":"02:18.995 ","End":"02:22.290","Text":"it\u0027s the same as multiplying by the reciprocal of the fraction."},{"Start":"02:22.290 ","End":"02:29.825","Text":"It\u0027s the same as taking the ions per mole times the mole per kilojoules."},{"Start":"02:29.825 ","End":"02:31.595","Text":"The moles cancel out,"},{"Start":"02:31.595 ","End":"02:37.815","Text":"and we\u0027re left with ions per kilojoules."},{"Start":"02:37.815 ","End":"02:40.280","Text":"Again, in order to find the number of"},{"Start":"02:40.280 ","End":"02:43.595","Text":"the sodium ions which are produced per kilojoule of energy,"},{"Start":"02:43.595 ","End":"02:47.045","Text":"which is absorbed by the sodium atoms,"},{"Start":"02:47.045 ","End":"02:53.555","Text":"all we did is take the number of ions which are produced per mole,"},{"Start":"02:53.555 ","End":"02:57.710","Text":"divided by the energy which is required per"},{"Start":"02:57.710 ","End":"03:02.690","Text":"mole and this gave us the number of ions per kilojoule of energy."},{"Start":"03:02.690 ","End":"03:08.530","Text":"Again, our answer equals 1.21 times 10^23 ions per kilojoule."},{"Start":"03:08.530 ","End":"03:09.710","Text":"That is our final answer."},{"Start":"03:09.710 ","End":"03:12.330","Text":"Thank you very much for watching."}],"ID":23843},{"Watched":false,"Name":"Electron Affinity","Duration":"6m 59s","ChapterTopicVideoID":20268,"CourseChapterTopicPlaylistID":90862,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:01.785","Text":"In the previous video,"},{"Start":"00:01.785 ","End":"00:04.470","Text":"we learned about the ionization energy."},{"Start":"00:04.470 ","End":"00:10.125","Text":"In this video, we\u0027ll talk about the related topic of electron affinity."},{"Start":"00:10.125 ","End":"00:13.575","Text":"What did we learn about ionization energy?"},{"Start":"00:13.575 ","End":"00:17.625","Text":"We learned that the ionization energy is the minimum energy"},{"Start":"00:17.625 ","End":"00:22.295","Text":"required to remove an electron from an atom in the gas phase."},{"Start":"00:22.295 ","End":"00:24.605","Text":"What about the electron affinity?"},{"Start":"00:24.605 ","End":"00:27.150","Text":"Electron affinity is the energy change,"},{"Start":"00:27.150 ","End":"00:32.820","Text":"that\u0027s the change in enthalpy when an atom gains an electron in the gas phase."},{"Start":"00:32.820 ","End":"00:36.740","Text":"Ionization energy is about removing an electron,"},{"Start":"00:36.740 ","End":"00:40.864","Text":"and electron affinity is about gaining an electron."},{"Start":"00:40.864 ","End":"00:44.630","Text":"We can write the electron affinity in this way; X,"},{"Start":"00:44.630 ","End":"00:47.960","Text":"which is some element in the gas phase,"},{"Start":"00:47.960 ","End":"00:54.990","Text":"plus an electron in the gas phase to form an anion of X in the gas phase."},{"Start":"00:54.990 ","End":"00:58.530","Text":"The energy change is Delta H_ea,"},{"Start":"00:58.530 ","End":"01:01.950","Text":"ea for electron affinity."},{"Start":"01:01.950 ","End":"01:05.825","Text":"Let\u0027s take some examples from Group 16 and 17."},{"Start":"01:05.825 ","End":"01:11.810","Text":"Now these are nonmetals most likely to form negative ions."},{"Start":"01:11.810 ","End":"01:16.430","Text":"For them, the Delta H_ea is very negative,"},{"Start":"01:16.430 ","End":"01:19.190","Text":"its most negative in the periodic table."},{"Start":"01:19.190 ","End":"01:23.305","Text":"First, let\u0027s consider Group 17, the halides."},{"Start":"01:23.305 ","End":"01:29.370","Text":"For fluorine, Delta H_ea is minus 328."},{"Start":"01:29.370 ","End":"01:32.985","Text":"For chlorine, minus 349."},{"Start":"01:32.985 ","End":"01:35.910","Text":"For bromine, minus 325."},{"Start":"01:35.910 ","End":"01:40.355","Text":"For iodine, minus 295 kilojoules per mole."},{"Start":"01:40.355 ","End":"01:42.700","Text":"What about Group 16?"},{"Start":"01:42.700 ","End":"01:49.900","Text":"Here, oxygen, minus 141 kilojoules per mole, sulfur,"},{"Start":"01:49.900 ","End":"01:52.720","Text":"minus 200, selenium,"},{"Start":"01:52.720 ","End":"01:57.400","Text":"minus 195, and tellurium, minus 190."},{"Start":"01:57.400 ","End":"02:01.450","Text":"We can see that the values for the halogens are much"},{"Start":"02:01.450 ","End":"02:06.685","Text":"greater than the values for Group 16 beginning with oxygen."},{"Start":"02:06.685 ","End":"02:10.375","Text":"Now Delta H_ea being negative,"},{"Start":"02:10.375 ","End":"02:17.155","Text":"Delta H_ea less than 0 means that the ion is more stable than the parent atom."},{"Start":"02:17.155 ","End":"02:22.030","Text":"This is very important to Group 17 where chlorine minus"},{"Start":"02:22.030 ","End":"02:27.075","Text":"the chloride anion is isoelectronic with argon,"},{"Start":"02:27.075 ","End":"02:29.190","Text":"and so is very stable."},{"Start":"02:29.190 ","End":"02:32.585","Text":"All the Group 17 anions are"},{"Start":"02:32.585 ","End":"02:38.450","Text":"isoelectronic with various noble gases and they\u0027re all very stable."},{"Start":"02:38.450 ","End":"02:42.275","Text":"That\u0027s why the values are greater for Group 17,"},{"Start":"02:42.275 ","End":"02:45.995","Text":"more negative than Group 16."},{"Start":"02:45.995 ","End":"02:48.885","Text":"Let\u0027s take another example of oxygen."},{"Start":"02:48.885 ","End":"02:54.575","Text":"Oxygen plus electron gives us all minus anion,"},{"Start":"02:54.575 ","End":"03:03.125","Text":"and we saw above that Delta H_ea for this is minus a 141 kilojoules per mole."},{"Start":"03:03.125 ","End":"03:07.430","Text":"But oxygen minus is not the common anion of oxygen."},{"Start":"03:07.430 ","End":"03:13.640","Text":"We need to add another electron in order to get O^2 minus."},{"Start":"03:13.640 ","End":"03:18.620","Text":"O minus plus electron to give us O^2 minus has"},{"Start":"03:18.620 ","End":"03:24.545","Text":"a Delta H_ea of plus 844 kilojoules per mole."},{"Start":"03:24.545 ","End":"03:27.800","Text":"When the second electron is added,"},{"Start":"03:27.800 ","End":"03:32.280","Text":"we find we have an endothermic process."},{"Start":"03:39.290 ","End":"03:45.105","Text":"When we add the 2 equations together to give us O,"},{"Start":"03:45.105 ","End":"03:50.325","Text":"in the gas phase plus 2 electrons to form O^2 minus,"},{"Start":"03:50.325 ","End":"03:52.710","Text":"and we add Delta H,"},{"Start":"03:52.710 ","End":"03:59.425","Text":"then we get Delta H is equal to plus 703 kilojoules per mole."},{"Start":"03:59.425 ","End":"04:05.300","Text":"Now we have the formation of O^2 minus as an endothermic process,"},{"Start":"04:05.300 ","End":"04:09.455","Text":"which suggests O^2 minus at least in the gas phase,"},{"Start":"04:09.455 ","End":"04:12.950","Text":"is less stable than O."},{"Start":"04:12.950 ","End":"04:15.365","Text":"Now why is this the case?"},{"Start":"04:15.365 ","End":"04:22.925","Text":"It\u0027s very strange since O^2 minus is isoelectronic with neon and its usual anion of O."},{"Start":"04:22.925 ","End":"04:26.720","Text":"Why is Delta H_ea positive?"},{"Start":"04:26.720 ","End":"04:32.915","Text":"The reason is that we need to invest energy to attach an electron to an anion."},{"Start":"04:32.915 ","End":"04:38.720","Text":"This second process where we\u0027re attaching electron to an anion is extremely"},{"Start":"04:38.720 ","End":"04:46.100","Text":"endothermic because we have negative and negative charges which repel each other."},{"Start":"04:46.100 ","End":"04:52.399","Text":"Should point out that when O^2 minus is found in an ionic crystal or in a solution,"},{"Start":"04:52.399 ","End":"04:55.805","Text":"there are always other energy processes involved"},{"Start":"04:55.805 ","End":"05:00.170","Text":"that compensate for the endothermic formation of the ion in the gas phase."},{"Start":"05:00.170 ","End":"05:02.000","Text":"For example, in a solution,"},{"Start":"05:02.000 ","End":"05:04.535","Text":"it could be the solvation energy,"},{"Start":"05:04.535 ","End":"05:07.289","Text":"which is very negative,"},{"Start":"05:09.410 ","End":"05:11.714","Text":"or in a crystal,"},{"Start":"05:11.714 ","End":"05:14.350","Text":"the lattice energy,"},{"Start":"05:15.170 ","End":"05:18.165","Text":"which is very negative."},{"Start":"05:18.165 ","End":"05:24.904","Text":"These will compensate for the endothermic formation of O^2 minus."},{"Start":"05:24.904 ","End":"05:27.500","Text":"Now what about noble gases?"},{"Start":"05:27.500 ","End":"05:31.425","Text":"Noble gases have complete S and P subshells."},{"Start":"05:31.425 ","End":"05:37.445","Text":"We have to add an additional electron to a new shell far from the nucleus."},{"Start":"05:37.445 ","End":"05:43.115","Text":"The noble gases all have small positive values of Delta H_ea."},{"Start":"05:43.115 ","End":"05:47.990","Text":"They tend not to form negative anions."},{"Start":"05:47.990 ","End":"05:50.370","Text":"Now in some textbooks,"},{"Start":"05:50.370 ","End":"05:54.815","Text":"other definitions are used for the electron affinity."},{"Start":"05:54.815 ","End":"06:01.720","Text":"Some textbooks define the electron affinity as E_ea equal to minus Delta H_ea."},{"Start":"06:01.720 ","End":"06:06.365","Text":"In other words, it has the opposite sign from Delta H_ea."},{"Start":"06:06.365 ","End":"06:09.065","Text":"That would mean, for example,"},{"Start":"06:09.065 ","End":"06:12.125","Text":"that for fluorine or for oxygen,"},{"Start":"06:12.125 ","End":"06:15.645","Text":"then ea would be positive,"},{"Start":"06:15.645 ","End":"06:19.050","Text":"whereas Delta H_ea is negative."},{"Start":"06:19.050 ","End":"06:21.125","Text":"This is we\u0027re more intuitive,"},{"Start":"06:21.125 ","End":"06:26.840","Text":"since 1 expects that are more positive affinity means a stronger attraction."},{"Start":"06:26.840 ","End":"06:29.630","Text":"Affinity means subtraction after all."},{"Start":"06:29.630 ","End":"06:32.520","Text":"Now what about the trends?"},{"Start":"06:32.530 ","End":"06:37.984","Text":"Now the trends are less clear than for ionization energy."},{"Start":"06:37.984 ","End":"06:42.845","Text":"But the clearest statement one can make is the highest values of"},{"Start":"06:42.845 ","End":"06:48.425","Text":"E_ea are on the top right-hand side of the periodic table,"},{"Start":"06:48.425 ","End":"06:51.525","Text":"whereas Z_effective is highest,"},{"Start":"06:51.525 ","End":"06:55.490","Text":"and where we have the nonmetals for after all,"},{"Start":"06:55.490 ","End":"06:59.730","Text":"it\u0027s a nonmetals that form anions."}],"ID":21061}],"Thumbnail":null,"ID":90862},{"Name":"Atomic Properties","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Magnetic Properties of Atoms","Duration":"2m 44s","ChapterTopicVideoID":20263,"CourseChapterTopicPlaylistID":90863,"HasSubtitles":true,"ThumbnailPath":"https://www.proprep.uk/Images/Videos_Thumbnails/20263.jpeg","UploadDate":"2019-11-05T12:55:16.4670000","DurationForVideoObject":"PT2M44S","Description":null,"MetaTitle":"Magnetic Properties of Atoms: Video + Workbook | Proprep","MetaDescription":"Periodic Table and Atomic Properties - Atomic Properties. Watch the video made by an expert in the field. Download the workbook and maximize your learning.","Canonical":"https://www.proprep.uk/general-modules/all/general-chemistry/periodic-table-and-atomic-properties/atomic-properties/vid21056","VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.385","Text":"In previous videos, we learned about the electron configuration of atoms."},{"Start":"00:05.385 ","End":"00:08.550","Text":"In this video, we\u0027ll learn about related property,"},{"Start":"00:08.550 ","End":"00:11.850","Text":"the magnetic properties of atoms."},{"Start":"00:11.850 ","End":"00:15.075","Text":"Let\u0027s recall what we learned about spin."},{"Start":"00:15.075 ","End":"00:18.900","Text":"An electron creates a magnetic field due to its spin."},{"Start":"00:18.900 ","End":"00:21.300","Text":"An electron with spin up will generate"},{"Start":"00:21.300 ","End":"00:25.845","Text":"an electric field in the opposite direction to the electron with spin down."},{"Start":"00:25.845 ","End":"00:27.945","Text":"This is illustrated here."},{"Start":"00:27.945 ","End":"00:33.430","Text":"Here\u0027s an electron with spin up the way, that means m_s=1/2."},{"Start":"00:34.130 ","End":"00:36.870","Text":"Here\u0027s the magnetic field."},{"Start":"00:36.870 ","End":"00:38.505","Text":"This is like the North Pole,"},{"Start":"00:38.505 ","End":"00:40.065","Text":"this is South Pole."},{"Start":"00:40.065 ","End":"00:44.530","Text":"Here\u0027s an electron with spin m_s=-1/2."},{"Start":"00:45.460 ","End":"00:52.475","Text":"Here\u0027s the magnetic field with the south pointing downwards and the north to the top."},{"Start":"00:52.475 ","End":"00:58.550","Text":"We can see the magnetic field here is the opposite direction from this one."},{"Start":"00:58.550 ","End":"01:01.910","Text":"Now, what\u0027s a diamagnetic atom?"},{"Start":"01:01.910 ","End":"01:07.580","Text":"An atom where all the electrons appeared does not generate a net magnetic field."},{"Start":"01:07.580 ","End":"01:11.600","Text":"We saw that one\u0027s pointing upwards and the other one\u0027s pointing downwards,"},{"Start":"01:11.600 ","End":"01:12.980","Text":"so they cancel each other."},{"Start":"01:12.980 ","End":"01:15.530","Text":"It is said to be diamagnetic."},{"Start":"01:15.530 ","End":"01:20.150","Text":"That means the sample is slightly repelled by an external magnetic field."},{"Start":"01:20.150 ","End":"01:22.940","Text":"What\u0027s the paramagnetic atom?"},{"Start":"01:22.940 ","End":"01:27.050","Text":"An atom with unpaired spins is paramagnetic."},{"Start":"01:27.050 ","End":"01:31.160","Text":"It means it\u0027s weakly attracted by an external magnetic field."},{"Start":"01:31.160 ","End":"01:33.065","Text":"The more unpaired spins,"},{"Start":"01:33.065 ","End":"01:36.005","Text":"the stronger the paramagnetism."},{"Start":"01:36.005 ","End":"01:39.335","Text":"Let\u0027s take the example of chromium."},{"Start":"01:39.335 ","End":"01:43.700","Text":"Chromium has the configuration of argon,"},{"Start":"01:43.700 ","End":"01:47.570","Text":"1 electron in 4s and 5 electrons in 3d,"},{"Start":"01:47.570 ","End":"01:50.575","Text":"so it has 6 unpaired spins,"},{"Start":"01:50.575 ","End":"01:56.820","Text":"1 in 4s and 5 in 3d."},{"Start":"01:59.830 ","End":"02:07.255","Text":"It will have strong paramagnetic properties because it has 6 unpaired spins."},{"Start":"02:07.255 ","End":"02:10.410","Text":"Now, if we look at its ion, chromium 3+,"},{"Start":"02:10.410 ","End":"02:16.915","Text":"we learned before that that has the configuration of argon and 3 electrons in 3d,"},{"Start":"02:16.915 ","End":"02:19.715","Text":"so it\u0027s 3 unpaired spins."},{"Start":"02:19.715 ","End":"02:23.860","Text":"Now, we only have 3 unpaired spins."},{"Start":"02:25.910 ","End":"02:34.060","Text":"It\u0027s paramagnetic properties will be much lower than those of chromium atom."},{"Start":"02:34.060 ","End":"02:39.245","Text":"The ion is less paramagnetic than the atom."},{"Start":"02:39.245 ","End":"02:44.310","Text":"In this video, we learned about the magnetic properties of atoms."}],"ID":21056},{"Watched":false,"Name":"Polarizability","Duration":"2m 18s","ChapterTopicVideoID":20264,"CourseChapterTopicPlaylistID":90863,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:01.740","Text":"In a previous video,"},{"Start":"00:01.740 ","End":"00:04.260","Text":"we learned about the atomic radius."},{"Start":"00:04.260 ","End":"00:09.915","Text":"In this video, we\u0027ll talk about the related topic of atomic polarizability."},{"Start":"00:09.915 ","End":"00:11.775","Text":"What\u0027s the polarizability?"},{"Start":"00:11.775 ","End":"00:13.230","Text":"For an isolated atom,"},{"Start":"00:13.230 ","End":"00:16.155","Text":"the electron charge distribution is spherical."},{"Start":"00:16.155 ","End":"00:20.580","Text":"Here it is, in the presence of an electric field or near another atom,"},{"Start":"00:20.580 ","End":"00:24.870","Text":"molecule or ion, the charge distribution becomes distorted."},{"Start":"00:24.870 ","End":"00:28.920","Text":"Supposing these are two electrically charged plates"},{"Start":"00:28.920 ","End":"00:34.450","Text":"supposing this as positive, and this is negative."},{"Start":"00:34.670 ","End":"00:41.980","Text":"Then the electron charge will move towards the positive plate."},{"Start":"00:44.390 ","End":"00:52.400","Text":"Now, the center of mass of the electric charge is displaced from the nucleus."},{"Start":"00:52.400 ","End":"00:56.885","Text":"It\u0027s no longer centered upon the nucleus so say it\u0027s found here."},{"Start":"00:56.885 ","End":"00:59.840","Text":"The atom is said to be polarized,"},{"Start":"00:59.840 ","End":"01:05.075","Text":"the polarizability Alpha is a measure of how easy it is to polarize the atom."},{"Start":"01:05.075 ","End":"01:10.400","Text":"Now, we can show that the polarizability is proportional to the volume of the atom."},{"Start":"01:10.400 ","End":"01:13.790","Text":"Alpha is proportional to V,"},{"Start":"01:13.790 ","End":"01:14.810","Text":"the volume of the atom,"},{"Start":"01:14.810 ","End":"01:19.390","Text":"which is 4/3 Pi times r^3."},{"Start":"01:19.390 ","End":"01:21.464","Text":"If the radius increases,"},{"Start":"01:21.464 ","End":"01:23.625","Text":"so will the polarizability."},{"Start":"01:23.625 ","End":"01:27.920","Text":"It\u0027s important to point out that the loosely bound valence electrons,"},{"Start":"01:27.920 ","End":"01:31.549","Text":"that\u0027s electrons that are farthest"},{"Start":"01:31.549 ","End":"01:35.780","Text":"from the nucleus contribute most to the polarizability."},{"Start":"01:35.780 ","End":"01:37.520","Text":"Now what are the trends?"},{"Start":"01:37.520 ","End":"01:40.565","Text":"Again, we\u0027re referring to the main group elements."},{"Start":"01:40.565 ","End":"01:44.540","Text":"The polarizability and atomic radius decrease from"},{"Start":"01:44.540 ","End":"01:48.920","Text":"left to right across a period and increase down a group."},{"Start":"01:48.920 ","End":"01:53.000","Text":"The blue indicates the polarizability Alpha,"},{"Start":"01:53.000 ","End":"02:00.080","Text":"which is increases from right to left and increases down the group,"},{"Start":"02:00.080 ","End":"02:01.835","Text":"so that\u0027s Alpha,"},{"Start":"02:01.835 ","End":"02:09.215","Text":"and the atomic radius r behaves in the same way,"},{"Start":"02:09.215 ","End":"02:12.950","Text":"increases from right to left and down the group."},{"Start":"02:12.950 ","End":"02:18.690","Text":"In this video, we talked about the atomic polarizability."}],"ID":21057}],"Thumbnail":null,"ID":90863}]

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