00:00:01 Okay.

00:00:05 I'm trying to remember which...

00:00:08 I think it was gallium.

00:00:21 Okay. Shall we start, Professor Seaborg?

00:00:24 Yeah. All right.

00:00:25 Okay.

00:00:26 Well, we're here at the National Academy of Sciences with Professor Glenn Seaborg from Berkeley

00:00:32 to talk about the periodic table.

00:00:35 And we'll start with the first obvious question,

00:00:39 and that is, what is it?

00:00:41 What is the periodic table?

00:00:43 Well, the periodic table is a unifying principle.

00:00:48 The elements are lined up in the order of their ascending atomic number.

00:00:53 Of course, in the first place, when Mendeleev conceived of it back in 1869...

00:01:02 Is that too much? Do I stop when that...

00:01:07 I was trying to...

00:01:10 All right. So then we'll go ahead. Okay.

00:01:13 All right.

00:01:15 Start again.

00:01:16 Okay.

00:01:17 What is the periodic table?

00:01:19 The periodic table is a unifying principle.

00:01:24 The chemical elements are lined up in the order of increasing atomic number.

00:01:31 In the first place, when Mendeleev conceived of this unifying principle,

00:01:39 back in 1869, he lined the elements up in the order of the increasing atomic weight.

00:01:46 But when the concept of atomic number, that is, the number of protons in the nucleus,

00:01:51 was conceived,

00:01:55 it became apparent that it should be according to the atomic number.

00:02:02 And then, as these are lined up, the properties repeat themselves.

00:02:08 So you start over again and go along in rows,

00:02:12 and the net result is that elements with similar chemical properties fall in columns.

00:02:21 And this gives a great predictive potential in the case of elements

00:02:28 that had not been discovered yet in the course of the history of the chemical elements.

00:02:33 So it's both a summary of information and it's also a predictor.

00:02:39 It also gives a power of prediction.

00:02:44 And Mendeleev used that to predict the chemical properties of elements

00:02:49 that hadn't been discovered yet back in 1869 in the subsequent versions.

00:02:54 Elements like gallium, between zinc and germanium.

00:03:00 He could predict the properties from extrapolation of those elements

00:03:07 above it and below it in the periodic table.

00:03:11 And it's been used that way throughout history

00:03:13 to predict the chemical properties of undiscovered elements,

00:03:17 including the heaviest elements,

00:03:21 the synthetic man-made elements beyond uranium,

00:03:26 the so-called transuranium elements that have been the subject of investigation

00:03:32 in my research throughout most of my life.

00:03:35 Okay, we'll come back to those.

00:03:38 Talk a little bit about the names of the elements.

00:03:43 Where do their names come from?

00:03:45 Well, a number of them.

00:03:47 Perhaps 10 or 15.

00:03:51 The names go back to prehistoric times.

00:03:54 There is no way of really pinning down who applied the names.

00:04:02 But since the discovery of the first element that was recorded in history,

00:04:10 and that happened to be the element phosphorus,

00:04:14 discovered by a German physician, Brandt,

00:04:21 the names have been applied by the discoverer of the element.

00:04:28 It has become traditional in the course of history

00:04:32 that the discoverer of the element has the right of applying the names.

00:04:37 Of course, in some cases where there have been disputes,

00:04:44 more or less simultaneous discovery,

00:04:46 this has led to the problem of adjudication as to who had the right to give it the name.

00:04:53 Which ones did you discover, and how did you choose the names?

00:04:56 Well, in my case, we used the term discover loosely.

00:05:05 It would be more correct to say synthesized than identified,

00:05:10 but we used the term discover.

00:05:13 Those that I have been involved with, my co-workers,

00:05:18 in the synthesis and identification are a number of the elements beyond uranium,

00:05:24 which has the atomic number 92,

00:05:28 beginning with plutonium, which has the atomic number 94,

00:05:33 and then going up to americium 95, curium 96,

00:05:38 berkelium 97, californium 98, einsteinium 99,

00:05:43 fermium 100, mendelevium 101, and nobelium 102.

00:05:50 Then I went to Washington to serve in the government

00:05:54 as chairman of the Atomic Energy Commission for ten years,

00:05:57 and during that interval my co-workers synthesized and identified the next two elements,

00:06:03 the 103 elements, 103 lorencium, 104 rutherfordium, and 105 honium.

00:06:12 Then when I returned, I participated in the discovery of the next element

00:06:16 with the atomic number 106, which doesn't have a name yet

00:06:20 due to this situation that I described.

00:06:23 There are competing claims to its discovery,

00:06:28 that is, for synthesis and identification.

00:06:32 Several of the elements have been named after famous scientists.

00:06:37 Perhaps you could just recap some of them.

00:06:39 Yes, well, the elements were named first,

00:06:45 well, I would say by three methods or principles.

00:06:50 The first two were named after the planets

00:06:54 because the last, the heaviest naturally occurring element, uranium,

00:07:00 was named after the planet Uranus.

00:07:02 So the next element, the element with the atomic number 93,

00:07:08 was named neptunium after the planet Neptune,

00:07:11 and then the next one, plutonium, after the planet Pluto.

00:07:16 Then at that point we ran out of planets

00:07:19 so that they were named on the basis of the comparison

00:07:28 with the homologous or analogous element in the periodic table.

00:07:33 And by this time we had deduced that they were members,

00:07:38 these transuranium elements were members of a second rare earth series,

00:07:42 and that the next element, 95, named americium,

00:07:48 was homologous or analogous to europium in the rare earths.

00:07:52 And because europium was named after the continent of Europe,

00:07:55 we named americium after the Americas.

00:07:58 The next element, curium, number 96,

00:08:03 was named after Marie Curie and Pierre Curie

00:08:11 because the element just above it, gadolinium,

00:08:15 the rare earth element, was named after a Finnish rare earth chemist.

00:08:19 Then the next element gave us a break.

00:08:23 That was named berkelium after the town where the University of California is situated

00:08:31 because the element just above it was named terbium,

00:08:35 named after a town in Sweden, Itterby, so we used that analogy.

00:08:40 However, when we came to element 98, the analogy broke down.

00:08:46 The element that would be analogous was named dysprosium,

00:08:51 and we looked that up in the dictionary,

00:08:53 and that comes after a...

00:08:58 is derived from a Greek word meaning...

00:09:03 a Greek word dysprositos, meaning difficult to get at,

00:09:07 and we didn't have a very good analogy there,

00:09:10 so we just named it after the state, California.

00:09:13 Although we made the facetious suggestion in the article describing its discovery

00:09:18 that California was difficult to get at back in the days of the 49ers

00:09:23 when they came out looking for gold.

00:09:26 And then at that point we just decided to begin to name the elements after famous scientists,

00:09:31 so 99 became einsteinium and 100 fermium.

00:09:35 101, mendelevium, after the great Russian scientist,

00:09:40 the originator of the periodic table that we're discussing.

00:09:44 102, nobelium, after the originator of the Nobel Prize.

00:09:52 103, lorencium, after Ernest Lawrence, the inventor of the cyclotron,

00:09:57 and then of course rutherfordium,

00:09:59 104, after the famous Ernest Rutherford, really the discoverer of the nucleus,

00:10:06 and 105, honium, after Otto Hahn, the discoverer of fission.

00:10:11 I didn't mention, Einstein didn't need any introduction,

00:10:17 and then fermium, for which 100 was named,

00:10:21 is the great Enrico Fermi, who was the originator of the first nuclear chain reaction.

00:10:26 And maybe a c-bogium one day.

00:10:29 Yes, except that one must realize that elements aren't named after living people.

00:10:36 They're only people who have passed on,

00:10:38 so I'll forgo that.

00:10:42 Let's move back a bit into the part of the table where the names are a little more familiar.

00:10:48 And maybe you could talk just for a few minutes about relative abundances of these elements,

00:11:00 because as I understand it, a few are very heavily represented on the planet.

00:11:06 Yes.

00:11:07 Many are very rare, and indeed the ones that you concern yourself with most don't exist at all here.

00:11:16 Maybe you could talk about that a little bit,

00:11:18 and then after that we'll talk a little bit about how far the periodic table could go in theory.

00:11:28 Yes, well, a number of the elements have large abundances on Earth.

00:11:36 We're all familiar with oxygen and nitrogen, carbon,

00:11:46 that really are the constituents, the main constituents of our bodies, and plants and so forth.

00:11:55 Then the number of the minerals like iron are abundant.

00:12:02 We go on down the scale until we find lower and lower abundances.

00:12:07 I mentioned the rare earths.

00:12:12 They were first considered to be quite rare in abundance,

00:12:17 and that's why they were given the name rare earths,

00:12:19 although as time has gone on, we find that there is a larger concentration

00:12:26 than it was first thought for these elements.

00:12:33 So they vary all the way down to where the elements like rhenium and hafnium and so forth

00:12:42 were found rather late in the history of the discovery of elements

00:12:47 because they are rather rare.

00:12:50 And we all know that elements like platinum and gold are somewhat rare,

00:12:59 difficult to find, but not extremely rare.

00:13:07 How do the lanthanide and actinide elements fit into the table?

00:13:11 Why is it that they're always separated from the main bulk of the table?

00:13:15 Yes, the rare earth elements that we refer to as the lanthanide elements

00:13:25 have 14 members, and they are formed successively

00:13:31 by the adding of an electron into an inner shell of the atom.

00:13:38 This results in their having similar chemical properties across the series,

00:13:46 and it would stretch out the periodic table to an impossibly wide expanse

00:13:57 if you fitted them all in between barium and hafnium

00:14:05 so that at that one place, lanthanum,

00:14:09 the 14 following elements are very much like lanthanum

00:14:13 and in a sense could be thought to all fill into that square.

00:14:17 But that would be cumbersome too. You couldn't fit them in there.

00:14:21 So they put them down at the bottom and stretch them out across.

00:14:25 Does the same principle apply with the actinides?

00:14:28 The same principle applies with the actinides.

00:14:31 The actinides, they're like actinium,

00:14:34 and they fill in as you go across an inner electron shell.

00:14:40 It's a little more outlying, but it's still an inner electron shell,

00:14:46 and therefore the best place for them would be to all fit into the spot

00:14:51 where actinium is between radium and thorium in the periodic table.

00:14:59 But as a matter of practicality,

00:15:03 then they're put down at the bottom of the periodic table

00:15:06 and stretched out in that manner.

00:15:09 Now, it's an interesting historical fact that it wasn't always that way.

00:15:16 Back in the days of Mendeleev and actually extending into the 1930s,

00:15:23 the heaviest elements, thorium, protactinium, and uranium,

00:15:28 were put into the periodic table up in the body of the periodic table

00:15:32 under hafnium and tantalum and tungsten.

00:15:39 And it was my idea in 1944,

00:15:43 while I was working at the Metallurgical Laboratory in Chicago

00:15:48 on the Manhattan Atomic Bomb Project,

00:15:51 that these might be misplaced

00:15:54 and that they might be the first three members of the actinide series.

00:15:59 And then I boldly, and against the advice of some of my eminent inorganic chemist friends,

00:16:07 plucked those out of the body of the periodic table

00:16:10 and put them in the row below

00:16:13 and then continued that with 93, 94, and so forth

00:16:17 up to 103 to get the 14 elements.

00:16:20 You see, you start with 90 and go through 103,

00:16:24 and that way you get the 14 actinide elements,

00:16:28 all like actinium, actinide, actinium-like,

00:16:32 in the row at the bottom of the periodic table.

00:16:34 And then I suggested we go back up into the body of the periodic table

00:16:41 and put in element 104 under hafnium where thorium used to be.

00:16:47 And 105 would come in under tantalum where prodactinium used to be.

00:16:54 And uranium would...

00:17:00 The next element, 106, would come in to the periodic table

00:17:05 where uranium used to be, under tungsten.

00:17:08 In general...

00:17:11 Okay.

00:17:18 ...along there, I suppose, by my calculation, 118 will be a noble gas.

00:17:24 That's exactly right. You did it exactly right.

00:17:27 Maybe. Okay.

00:17:29 Let's pick up on...

00:17:32 What motivated me?

00:17:33 Yes, back in the 40s when you made that, when you published your table.

00:17:38 Yes. All right.

00:17:43 I was motivated to make this change in the periodic table

00:17:49 by a certain uneasiness and unrest with the situation.

00:17:57 One day in July of 1944,

00:18:02 I was faced with the task of preparing a report for a meeting.

00:18:07 This would have been on a Friday,

00:18:09 for a meeting to be held on the following Monday

00:18:11 in which we were going to report progress on our research.

00:18:17 And I called in a secretary.

00:18:21 I'm Frank.

00:18:23 If you could start off one day in July.

00:18:26 Yeah. One day in July of 1944, it was a Friday,

00:18:31 I was faced with the task of preparing a report

00:18:36 for use at a meeting scheduled for the following Monday

00:18:40 in which we were to go over our work

00:18:43 and talk about the status of our various projects.

00:18:50 And I called in a secretary who could take shorthand,

00:18:56 but who had a technical background as well.

00:18:59 And in the course of preparing that report,

00:19:02 it just dawned on me that the periodic table was wrong

00:19:05 and that we should make this change.

00:19:07 We should shift the thorium, protectinium, uranium down below.

00:19:11 And as a result of that,

00:19:13 we would predict the chemical properties of the undiscovered elements 95 and 96.

00:19:19 We had been predicting them in an erroneous fashion.

00:19:23 We had decided that they would be chemically like uranium.

00:19:26 But under this arrangement,

00:19:28 because they fell under europium and gadolinium,

00:19:31 they would be chemically like europium and gadolinium.

00:19:34 And it was, by the way, on the basis of this

00:19:37 that we could go ahead and synthesize them

00:19:39 and identify them in the following months.

00:19:42 I presented this at that Monday seminar

00:19:45 and it went over like a lead balloon.

00:19:48 The idea that one would be brash enough to change the periodic table

00:19:53 after all these years in this fashion

00:19:56 when everybody felt that thorium, protectinium, and uranium

00:20:00 should be in those sacrosanct positions

00:20:03 up in the body of the periodic table

00:20:05 under hafnium, tantalum, and tungsten.

00:20:10 After the war,

00:20:13 when I was faced with the opportunity of publishing these ideas,

00:20:21 I showed this periodic table to some of my friends,

00:20:24 the most eminent inorganic chemists in the world,

00:20:27 and told them that I planned to publish it.

00:20:30 And they said, don't do it, Glenn.

00:20:32 It's wrong.

00:20:34 It will ruin your scientific reputation.

00:20:37 Well, I'm fond of saying that I had an advantage.

00:20:41 I didn't have any scientific reputation at that time.

00:20:44 So I went ahead and published it.

00:20:46 And it appeared in a December issue of Chemical and Engineering News, 1945.

00:20:53 And that set it off.

00:20:55 People gradually accepted it

00:20:59 as the correct form of the lower form of the periodic table.

00:21:04 And now it's universally accepted, as you can see, by this periodic table.

00:21:10 I gather you also discovered a couple of new elements

00:21:16 during the later period of the war.

00:21:18 Let me interrupt you for a second.

00:21:20 Let me get this, and then we'll get back to the scientific stuff.

00:21:24 You made a statement.

00:21:25 You said something to the effect that I realized the periodic table was wrong.

00:21:31 Can you tell me how did you realize that?

00:21:33 Do you remember the specific time that you realized it?

00:21:36 Yes.

00:21:38 I realized the periodic table was wrong

00:21:41 because we were not making any progress

00:21:45 in our attempts to synthesize and identify elements 95 and 96.

00:21:53 And I knew we needed a new approach.

00:21:57 It was necessary to predict accurately the chemical properties

00:22:01 because in the nuclear reactions in which these were formed,

00:22:05 they would be present in extremely small amounts

00:22:10 compared to the immense amount of other radioactivity

00:22:14 due to the fission products.

00:22:16 And we could not detect them with our sensitive instruments

00:22:19 without a chemical isolation procedure.

00:22:22 And it just occurred to me that if they fit into the periodic table in this new way,

00:22:30 as the second rare-earth series,

00:22:32 we had a new approach,

00:22:34 and we would try to isolate them as analogs of europium and gadolinium.

00:22:40 That was the thought.

00:22:42 Now, there was an interesting story

00:22:47 in connection with the announcement of their discovery.

00:22:51 We went on, and during the rest of 1944 and early 1945,

00:22:58 succeeded in synthesizing and chemically identifying these two elements.

00:23:03 After the war, I was given permission

00:23:07 through what they call a declassification process

00:23:10 to render the work non-secret

00:23:13 to describe this discovery of elements 95 and 96

00:23:18 and my ideas about the reconstitution of the periodic table

00:23:23 for presentation at a local meeting of the American Chemical Society

00:23:30 at Northwestern University in Chicago.

00:23:34 This was scheduled for Friday, November 16.

00:23:40 Now, it so happened that I was also scheduled to appear as a guest

00:23:46 on the Quiz Kids program

00:23:50 on Sunday, November 11, Armistice Day, 1945.

00:23:55 This is a program where a quiz master named Joe Kelly

00:24:00 asked an assembled group of about five or six kids

00:24:03 ranging in age from about five to 15 or 16

00:24:07 questions sent in by listeners in the radio audience.

00:24:14 In this program, they turned it around in the last half,

00:24:18 and the Quiz Kids asked me questions.

00:24:21 And one of them asked me,

00:24:23 By the way, were there any new elements discovered

00:24:27 in your work at the Metallurgical Laboratory during the war?

00:24:30 And I blurted out the answer, yes.

00:24:33 The elements with the atomic numbers 95 and 96 were discovered

00:24:37 because I was empowered to do this.

00:24:39 They had been rendered non-secret.

00:24:42 But this was the announcement to the world

00:24:45 of the discovery of elements 95 and 96.

00:24:48 Wonderful.

00:24:50 When you went into this meeting, that Monday morning meeting,

00:24:53 where you were going to tell them for the first time this report,

00:24:56 do you remember thoughts and feelings that were running through your mind at that time?

00:25:01 Well, I felt confident.

00:25:04 I felt very confident.

00:25:07 It was just, you know,

00:25:10 after thinking about this so long,

00:25:13 and I think way back in the back of my mind,

00:25:16 even at the time of the discovery of plutonium

00:25:20 at the University of California, 1940 and 1941,

00:25:24 that something was wrong.

00:25:27 No, it was just as if I sort of lit up.

00:25:32 I felt very confident and not too shaken

00:25:35 when the people in the audience,

00:25:38 again, some eminent inorganic chemist,

00:25:41 pooh-poohed the idea.

00:25:43 I thought, all I have to do now is go ahead and convince them.

00:25:47 And then, when this led to the discovery of elements 95 and 96,

00:25:53 the opposition dwindled,

00:25:57 but not to the extent that they wanted to actually see me publish this in a periodic table.

00:26:03 I was exposing myself.

00:26:06 I would be very vulnerable if that were wrong.

00:26:09 But again, I felt confident.

00:26:12 I had thought about it more than the others,

00:26:15 and it all fit together so well.

00:26:18 And it led to such predictive power,

00:26:21 because this made it possible to predict in detail

00:26:25 the chemical properties of the rest of the elements.

00:26:28 97 would be like terbium, 98 would be like dysprosium,

00:26:31 and go right across the table

00:26:34 until 103 would be like lutetium, element by element.

00:26:39 And that's the way it turned out.

00:26:41 As a result of this, it was possible to predict

00:26:44 the chemical properties of these elements,

00:26:46 97, 98, 99, 100, 101,

00:26:51 to such an extent that we knew their properties

00:26:54 before they were discovered

00:26:56 just about as well as we knew them after they were discovered.

00:26:59 We could devise experiments

00:27:04 by what we call in ion exchange,

00:27:07 adsorption, elution method, chromatography.

00:27:12 We could devise experiments

00:27:14 in which we use the analogy, element by element,

00:27:17 analogy with the rare earths,

00:27:19 so we could predict exactly where they would come off,

00:27:22 an adsorption, elution, chromatographic column.

00:27:26 As your theory was accepted

00:27:28 and you were able to achieve these things,

00:27:30 that must have been fantastically exciting.

00:27:33 Oh, it was. It was very exciting.

00:27:36 And then as we went on to identify elements 95, 90,

00:27:41 excuse me, 97, 98, 99, and so forth,

00:27:46 to predict the very drop in which it would come off a column

00:27:51 was exciting.

00:27:53 And as I say, then as the years went on,

00:27:57 the opposition evaporated.

00:27:59 Oh, there were a few diehards.

00:28:01 There were some who went on to their graves

00:28:05 not accepting the theory.

00:28:08 I'm fond of, or I've heard it said that

00:28:13 theories like this go through three stages.

00:28:17 One is you present it to the scientific world

00:28:21 and they don't believe it.

00:28:23 The second stage is there gets to be

00:28:26 a general acceptance of the theory.

00:28:30 And then the third stage is people said,

00:28:32 well, it was obvious in the first place.

00:28:36 Of course.

00:28:38 Do you remember, are there any stories

00:28:40 that stick in your mind, key points after you presented that theory

00:28:44 that you might want to share with us

00:28:47 that were turning points maybe in that acceptance process?

00:28:50 Oh, I would think probably when we went on

00:28:55 and were able to synthesize and identify the following elements,

00:28:59 97 and 98.

00:29:03 But of course in my own mind and in the mind of my colleagues,

00:29:06 the ability to synthesize and identify elements 95 and 96

00:29:14 were really the turning points.

00:29:16 Do you remember the day that that happened?

00:29:19 Of the 95 and 96?

00:29:21 It wasn't a matter of one day.

00:29:25 It was a matter of here it is and here it isn't.

00:29:27 You know, the small amounts,

00:29:29 barely detectable amounts of radioactivity.

00:29:33 It occurred during the fall of 1944

00:29:39 and into January 1945.

00:29:44 Yes, I do remember that I made a presentation of this,

00:29:49 having it all in place at a meeting of our group in January of 1945.

00:29:55 And I have notes of that meeting,

00:29:57 which are interesting to read.

00:29:59 Do you remember what thoughts were running through your mind then?

00:30:02 Well, it's a little difficult.

00:30:08 When you're working on a problem like this

00:30:13 and it gradually unravels and so forth,

00:30:18 you have a feeling of satisfaction,

00:30:20 but also it has come along in such a manner

00:30:27 and so logically and so forth

00:30:29 that I can't say that there's any one moment

00:30:33 when you say, Eureka, or this is it.

00:30:37 That's wonderful.

00:30:38 I need to backtrack a little bit back to the beginning

00:30:40 of what you were talking about.

00:30:42 For editing purposes,

00:30:45 I'd like to ask you the question,

00:30:47 and I'm not being flippant,

00:30:49 but I'm kind of asking it as a student coming in

00:30:52 for the first time encountering the periodic table.

00:30:56 What is so important about the periodic table?

00:30:59 Why is it such a crucial and fundamental tool for chemists?

00:31:05 Well, because it unifies so much knowledge.

00:31:11 Let me know what you just said.

00:31:13 If you could start your answer with this,

00:31:15 the periodic table is so important.

00:31:17 The periodic table is so important

00:31:19 because it codifies and unifies so much knowledge.

00:31:25 It gives you the change in properties as you go down.

00:31:33 I'm sorry.

00:31:34 Go ahead.

00:31:36 Okay, we're going to start again.

00:31:38 If you can repeat a little bit of this.

00:31:40 What is so important about the periodic table?

00:31:42 The periodic table is so important

00:31:45 because it codifies and unifies so much knowledge.

00:31:49 Throughout history, it has led to the prediction

00:31:53 of the chemical properties of undiscovered elements

00:31:56 before they are discovered.

00:31:58 Without that guidance,

00:32:00 it would not have been possible to discover the elements.

00:32:03 It describes the trends in the properties of these elements

00:32:06 in the columns within the families of similar elements,

00:32:13 how these change as the elements become heavier.

00:32:17 It relates to the atomic structure,

00:32:20 which developed after the periodic table was conceived.

00:32:26 It gets into the fine points of this atomic structure

00:32:30 so that when you get to the upper end

00:32:33 where we're now working and trying to measure

00:32:38 through extremely difficult experiments

00:32:41 the chemical properties of the various heaviest elements

00:32:45 that are available with sufficiently long half-lives

00:32:48 to do experiments, elements 103 and 104 and 105,

00:32:52 it enables us to test certain relativistic principles

00:32:57 because the electrons are moving faster

00:32:59 as you get heavier and heavier elements.

00:33:02 And this leads to subtle changes

00:33:06 in the predictions of the chemical properties

00:33:09 from just a straight extrapolation.

00:33:11 And we can make those predictions

00:33:15 and then test them in the laboratory with these experiments.

00:33:19 No, it's a very powerful unifying principle.

00:33:25 Okay, along that line,

00:33:29 why was the development of the periodic table,

00:33:31 I'm not sure I'm phrasing this right,

00:33:33 but why was the development of the periodic table

00:33:35 such an important step in the history of chemistry

00:33:38 or the history of science in general?

00:33:40 Well, the reason that the periodic table

00:33:44 was such an important step

00:33:46 is that it gave, for the first time, a blueprint.

00:33:52 Before this, the elements were just scrambled and unrelated.

00:33:57 And in the periodic table, each element relates to the other one.

00:34:01 And then as time went on

00:34:03 and the concept of atomic number evolved,

00:34:08 it became even on a better footing.

00:34:14 And then as atomic structure became understood

00:34:21 and Niels Bohr, Rutherford,

00:34:26 so far as the nucleus is concerned,

00:34:28 and Niels Bohr with respect to the structure

00:34:31 of the electrons outside the nucleus,

00:34:33 as they got into the act,

00:34:36 it became apparent that we just had a beautiful,

00:34:39 coherent picture of, really, all of nature,

00:34:44 all of the chemical elements,

00:34:45 which constitutes all of nature.

00:34:48 Okay, when we first got what it was,

00:34:59 how would you tell someone why they should be interested?

00:35:06 What was your first reaction to the periodic table,

00:35:09 and then how did that change?

00:35:12 Did you want to get into how I got into science, too,

00:35:15 at some stage?

00:35:16 Sure, I'd be very interested in that.

00:35:18 I could go into that, yeah. Okay.

00:35:21 Okay, so what was your first reaction to the periodic table?

00:35:24 Well, I first encountered the periodic table

00:35:27 in my high school chemistry course.

00:35:31 I don't think, frankly, that I appreciated it then.

00:35:36 It's just as I went on and became better versed in chemistry

00:35:42 that I understood what a powerful, unifying principle it was.

00:35:49 I might mention how I happened to take up

00:35:54 a scientific career at all.

00:35:56 Actually, I went to high school

00:36:00 in the Watts District of Los Angeles.

00:36:03 I was bussed in from a neighboring town into Watts,

00:36:08 and when I started in the ninth grade,

00:36:12 I decided to major,

00:36:16 insofar as you can major in high school, in literature.

00:36:19 I took world history and oral English and English,

00:36:22 and of course I did take algebra and a foreign language,

00:36:26 Spanish, which was the only language offered

00:36:29 in the Los Angeles area, in that high school anyway.

00:36:33 But no science, because it didn't look interesting to me.

00:36:36 I looked at the book, and there were the lists of the planets

00:36:39 and so forth, and I thought, well, I can read about this.

00:36:42 I don't need to take a course.

00:36:44 Then I got to my sophomore year,

00:36:46 and then it would have been biology.

00:36:49 Well, that didn't look very interesting to me,

00:36:52 so I didn't take that.

00:36:54 And it wasn't until my junior year

00:36:57 that the teachers said to me,

00:37:00 Glenn, if you want to go to the university,

00:37:03 particularly the state university, the tuition-free university,

00:37:06 the only one that I could afford,

00:37:08 you have to take a laboratory course.

00:37:10 That's a prerequisite.

00:37:12 So I enrolled for chemistry,

00:37:14 and then I had a chemistry teacher that just turned me on.

00:37:18 My attitude almost from the beginning was,

00:37:21 well, why hadn't anybody told me about these things?

00:37:24 And I just decided then to be a scientist.

00:37:30 This teacher preached chemistry.

00:37:34 He wasn't a great scientist,

00:37:36 but he told stories about the scientific controversies

00:37:40 that were raging.

00:37:42 They described leading scientists to us and so forth.

00:37:45 And I just loved it.

00:37:47 And then in my senior year, I took physics.

00:37:50 There was a small high school,

00:37:52 and they alternated between chemistry and physics,

00:37:55 the same teacher.

00:37:57 And I liked physics even better than chemistry.

00:38:00 But in those days, nobody knew what physics was.

00:38:04 If I wanted to make a living,

00:38:06 it appeared clear to me that it would be better to be in chemistry.

00:38:10 So I then enrolled at UCLA across town

00:38:13 and majored in chemistry,

00:38:15 and I took about as much physics as chemistry.

00:38:18 And then when I finished,

00:38:20 I had a course in atomic physics at UCLA,

00:38:25 learned about the work at Berkeley,

00:38:27 the invention of the cyclotron,

00:38:29 the fact that things were happening

00:38:33 in the understanding of the nucleus of the atom.

00:38:36 The neutron had been discovered.

00:38:38 This was all described in this course in atomic physics.

00:38:41 Artificial radioactivity had just been discovered.

00:38:44 This was in the early 30s.

00:38:46 And so I decided to go to Berkeley for graduate work.

00:38:49 I didn't apply anywhere else.

00:38:52 My physical chemistry teacher, James B. Ramsey,

00:38:57 was a graduate of Berkeley,

00:38:59 and he assured me I would be accepted there.

00:39:01 So then I went up to Berkeley

00:39:03 and got a degree in nuclear work.

00:39:07 Actually, it wasn't chemistry in a sense at all.

00:39:10 It was the scattering of neutrons and so forth.

00:39:13 And my first job after I received my Ph.D.

00:39:18 was as a personal research assistant

00:39:21 of the great physical chemist Gilbert Newton Lewis,

00:39:26 probably the greatest physical chemist in the world at that time,

00:39:30 the originator of the octet theory of electron structure,

00:39:34 the electron pair bond,

00:39:36 the writer of the Bible of thermodynamics,

00:39:42 chemical thermodynamics and so forth.

00:39:47 Okay.

00:39:50 Well, just as a break from things,

00:39:53 say a few words about your time.

00:39:56 It looks like a period of time.

00:39:59 We're going to have to rewind.

00:40:01 The program following this is on bonding.

00:40:04 And so the producer of that program

00:40:07 has thrown me three short questions.

00:40:12 Perhaps you could describe the excitement of working with Gilbert Lewis

00:40:18 after he developed this principle of shared electron pair bonding.

00:40:23 Yes.

00:40:24 In my work with Gilbert Lewis,

00:40:27 we investigated one of the concepts for which he became famous,

00:40:35 and that is of generalized acids and bases.

00:40:39 And we did simple experiments in the laboratory,

00:40:44 really laboratory bench test tube experiments,

00:40:48 testing his concepts of the great family of substances that could be acids

00:40:56 and the great family of substances that could be bases.

00:41:01 And I was so impressed by the sheer brilliance of his deductions.

00:41:09 He could take these simple test tube experiments,

00:41:12 which I performed for him,

00:41:14 and derive from them more conclusions and information

00:41:20 than I would have ever thought possible.

00:41:22 It was for me an absolutely marvelous start of a career as a scientist

00:41:33 to be working under the world master that way

00:41:36 and watching how his mind worked

00:41:39 and realizing that I could hold my own with him.

00:41:42 That gave me a good degree of self-confidence

00:41:45 that I didn't really have at that stage

00:41:48 and got me off to a good start.

00:41:50 Even though I was working in an entirely different field with him

00:41:54 than I was embarking on as a scientist,

00:42:01 namely the nuclear field.

00:42:03 And as a matter of fact,

00:42:04 I did a lot of moonlighting while I was working with Lewis

00:42:07 because before he came in the morning

00:42:09 and after he left in the afternoon

00:42:11 and during the evenings and weekends

00:42:13 when I wasn't occupied with him,

00:42:15 I was working in my own field of nuclear research.

00:42:18 And in fact, at that point,

00:42:21 I was working with Emilio Segre

00:42:24 where, among other things,

00:42:27 we synthesized and identified the isotope technetium-99m,

00:42:33 which, in the meantime,

00:42:35 has become the workhorse of nuclear medicine.

00:42:38 We, of course, didn't know that at that time.

00:42:41 But here's an isotope that is the daughter.

00:42:46 It has a half-life of only six hours,

00:42:49 but it's the daughter of a molybdenum isotope

00:42:51 that has a half-life of about three days.

00:42:54 And so hospitals throughout the United States

00:42:58 have these molybdenum cows, as they call them,

00:43:02 and they milk the six-hour activity out

00:43:05 and then use it for the diagnostic procedures

00:43:10 in the hospitals all across the United States.

00:43:14 It's the most used isotope.

00:43:16 There are millions of applications per year.

00:43:19 As a matter of fact,

00:43:20 almost anybody who's reached my age

00:43:23 has probably had a diagnostic procedure with this.

00:43:26 So I have been diagnosed,

00:43:29 had my thyroid examined.

00:43:32 It came out fine with technetium-99m,

00:43:35 and my wife has, too.

00:43:38 I'd like to...

00:43:39 We'll come back to Lewis in a minute,

00:43:41 but as you mentioned technetium,

00:43:43 as you were researching,

00:43:45 just say a little more about it,

00:43:47 its atomic number, where it occurs,

00:43:49 whether or not it occurs naturally.

00:43:51 Yes.

00:43:52 Technetium actually was the first synthetic element

00:43:58 discovered by Segre and his co-worker Perrier in Italy

00:44:03 using the part of a cyclotron bombarded in Berkeley.

00:44:07 It's a synthetic element.

00:44:09 It doesn't exist in nature.

00:44:12 It has the atomic number 43.

00:44:16 It's a shame.

00:44:19 Yeah.

00:44:21 Technetium is a synthetic element,

00:44:23 was the first synthetic element synthesized and identified.

00:44:28 It was identified by Segre and Perrier in Italy

00:44:34 in the middle of 1936 or 37,

00:44:39 and then Segre came to Berkeley in 1938

00:44:43 and sought me out as a collaborator,

00:44:45 and that is what led to the synthesis

00:44:48 and identification of technetium-99m.

00:44:52 The M just means metastable.

00:44:55 It's a particular form of radioactivity

00:44:58 in which an upper state of a nucleus

00:45:01 decays to a lower state

00:45:03 by what is called an isomeric transition,

00:45:06 and this was one of the first of those type of radioactive decays.

00:45:13 That was Segre's and my interest.

00:45:15 We didn't realize that it would have this tremendous application

00:45:19 in the diagnosis of disease

00:45:25 in many different organs in the human individual.

00:45:29 Okay. Back to Lewis a little bit more.

00:45:33 Tell me a little bit more about him as a person.

00:45:35 I mean, he sounds like he was a giant in his day.

00:45:40 Yes, Gilbert Newton Lewis was the physical chemist of his era.

00:45:48 What kind of a fellow was he?

00:45:51 He was a fine person to work with.

00:45:54 He was considerate.

00:45:59 He was brilliant.

00:46:02 He dictated his papers.

00:46:05 He would pace up and down.

00:46:07 He was an inveterate cigar smoker.

00:46:10 He just smoked, well, he just lit one cigar from the other

00:46:15 as he consumed the cigars,

00:46:18 and he would pace up and down in the laboratory

00:46:23 dictating the papers that we published together

00:46:26 on these generalized acids and bases.

00:46:30 Absolutely perfect sentence structure.

00:46:34 I couldn't improve on it in any degree whatsoever.

00:46:41 He ran the seminar at Berkeley, which became world famous.

00:46:48 He sat at the head of the desk of the table

00:46:52 where the senior faculty sat around the table.

00:46:57 It was not a large room.

00:46:59 It wasn't a big department in those days.

00:47:02 Then the postdocs on the next level

00:47:05 and then the graduate students on the periphery.

00:47:08 And he did this in just a masterful manner.

00:47:12 When the person finished the presentation,

00:47:16 there would first be a presentation by a graduate student,

00:47:20 a progress report on his or her research,

00:47:23 and then a more senior faculty member or postdoc.

00:47:27 Inevitably, when the person who was speaking finished,

00:47:31 Lewis had a cogent question, a remark to make,

00:47:36 and you had to be prepared.

00:47:38 He didn't suffer fools gladly.

00:47:40 It was almost a weakness of his.

00:47:43 There would be eminent professors from the East

00:47:46 come there and make a presentation at that seminar,

00:47:50 and if they didn't know what they were talking about,

00:47:52 he took them apart like they were a graduate student.

00:47:55 It got so that they were sort of shaking in their boots

00:47:58 as they came out to Berkeley to make their presentation.

00:48:04 He was a one of a kind.

00:48:06 When did he discover the principle of shared electron pair bond?

00:48:12 Lewis conceived his ideas of atomic structure,

00:48:19 the shared electron pair bond, the octet theory, and so forth,

00:48:23 in the teens, in the late 1916, 1917, 1918 era,

00:48:34 but of course continued to develop them into the 1920s.

00:48:40 This perhaps was his greatest contribution,

00:48:46 but he also put chemical thermodynamics on a firm basis

00:48:52 in the United States and throughout the world,

00:48:54 and his book, Chemical Thermodynamics,

00:48:56 was the Bible for years of people working in chemistry.

00:49:01 Did he do that?

00:49:03 I mean, with Schrodinger and his modification of Gatton,

00:49:07 that must have led to modifications of Lewis.

00:49:11 Well, Lewis's theory was complementary to Schrodinger's.

00:49:16 His was a more pictorial representation of the atom,

00:49:23 and in a very sophisticated degree,

00:49:30 probably is no longer strictly applicable,

00:49:34 but the electron pair bond is still applicable.

00:49:40 It's a very powerful principle in organic chemistry

00:49:44 and the understanding of the structure of molecules.

00:49:49 Did Lewis remain at Berkeley?

00:49:52 Yes.

00:49:54 Gilbert Lewis remained at Berkeley until his death

00:49:58 in the spring of 1946 at the age of 70.

00:50:07 He passed away just a month or two before I returned to Berkeley from Chicago,

00:50:15 where I worked on the atomic bomb during the war.

00:50:17 During the years 1942 to 1946,

00:50:21 I worked in the metallurgical laboratory at the University of Chicago

00:50:26 developing the chemical processes for the extraction of plutonium

00:50:31 after its production in the chain-reacting piles at Hanford, Washington,

00:50:38 the material that was developed for use in the atomic bomb

00:50:43 once we had proved in 1941

00:50:48 that it was fissionable with slow neutrons

00:50:52 and hence had the same intrinsic value as a nuclear fuel

00:50:57 as the rare isotope of uranium, U-235.

00:51:02 One final question about Lewis.

00:51:04 How significant was the shared electron pair bonding discovery

00:51:08 and how important is it today?

00:51:12 Oh, I'd say the shared electron bond concept today

00:51:17 is really the backbone of chemistry,

00:51:22 but in terms of relative importance,

00:51:26 it was just central at the period that it was developed.

00:51:33 It just brought everything together in a manner that could be understood

00:51:40 much better than had been possible before his conception of this idea.

00:51:47 Okay. Let's go back to the periodic table.

00:51:52 The question I brought up a little earlier

00:51:58 wouldn't be stretching the point to say that the periodic table

00:52:02 is a representation of electron configuration.

00:52:06 The periodic table, as it turned out,

00:52:10 it wasn't understood that in the first place in 1869,

00:52:15 but as it turned out, it is a representation of the electronic structure

00:52:21 of the atoms, of the elements.

00:52:27 How many elements are there?

00:52:32 There are a total now of 109 elements.

00:52:40 The last three were discovered in a laboratory at Darmstadt, Germany

00:52:47 by Armbruster and co-workers, I say discovered, synthesized, and identified.

00:52:53 The so-called GSI laboratory

00:52:58 on the basis of just a few atoms per experiment.

00:53:05 In the case of 109, its discovery was announced

00:53:09 on the basis of just producing one atom,

00:53:13 but it could be identified because it decayed

00:53:16 by the emission of alpha particles, that's helium ions,

00:53:20 to a previously known daughter.

00:53:23 And that way, of course, you get a complete identification.

00:53:26 That's by the method of genetic relationships.

00:53:29 And I believe that in the meantime they've produced a couple of more atoms.

00:53:43 Why these names in a smaller type than these ones?

00:53:47 Is there any reason for that?

00:53:55 Well, yes, in talking about the periodic table,

00:53:59 there is a dispute going on as to the best way of labeling these,

00:54:05 you know, the 1A, I mean the 1A, 1B, and so forth,

00:54:10 and they're different in Europe than they are in the United States.

00:54:15 And they're trying to come out with a scheme

00:54:21 that more or less goes from 1 to 16 or whatever it is,

00:54:26 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,

00:54:34 well, maybe it's not quite sure how that scheme goes.

00:54:39 I'll be very general, but it might be worth mentioning.

00:54:42 How many elements might there be?

00:54:48 We think that this island of stability, which we think is up around 114,

00:54:54 which would be under lead, by the way, if you count your way up there,

00:54:58 might be about as far as we'll go if we do succeed.

00:55:01 And you want to get a more up-to-date periodic table,

00:55:04 so you have 108 and 109 on it.

00:55:08 Yes.

00:55:11 Yes.

00:55:22 Yes.

00:55:27 Yes.

00:55:31 I think the periodic table has assumed its final form

00:55:37 The way we're going to modify it now is to just add more elements.

00:55:45 The scientists in this field have worked their way up to element 109.

00:55:50 I think it will be possible to synthesize elements

00:55:54 all the way up to the region of element 114,

00:55:57 which falls under lead in the periodic table.

00:56:01 It would be called echolead in the nomenclature of Mendeleev.

00:56:08 There should be increased stability.

00:56:11 They're not going to be stable,

00:56:13 but the half-lives are going to become longer

00:56:16 than at the present upper limit, at 109,

00:56:19 where the half-lives are of the order of milliseconds,

00:56:23 thousands of seconds.

00:56:26 What is going to be useful, more useful,

00:56:30 with respect to this so-called island of stability,

00:56:33 up around element 114,

00:56:35 is that the yields in chemical reactions,

00:56:38 we hope, in nuclear reactions,

00:56:40 we hope will increase.

00:56:42 The yield of 109 is so small

00:56:46 that in Germany,

00:56:48 it took three weeks of bombardments to form one atom.

00:56:53 We hope that the yields will increase

00:56:55 and the half-lives will increase

00:56:58 and become substantially longer than a millisecond

00:57:01 up around the element with atomic number 114.

00:57:05 I fully expect that it will be possible to go that far

00:57:09 and to modify the periodic table to that extent.

00:57:12 However, we feel confident

00:57:16 as to the form that the periodic table would take

00:57:21 if we could go on beyond element 118,

00:57:25 which is predicted to be the next noble gas.

00:57:30 We feel that the next element would be 119

00:57:34 in the alkali metal column under francium,

00:57:38 and then would come 120 in the alkaline earth column

00:57:42 under radium.

00:57:44 And then at 121,

00:57:46 we would expect that there would be a filling

00:57:49 of another inner electron shell,

00:57:52 another rare-earth type series,

00:57:54 which I have called the superactinide series.

00:57:57 That would commence at element 121.

00:58:02 But rather than have just 14 places,

00:58:06 filling the 14 places in an F shell,

00:58:09 there would, in addition, be the 18 places

00:58:12 in what we call a G shell.

00:58:14 And we predict that these would fill

00:58:17 in an intermingling fashion

00:58:19 so that you have 14 plus 18 equal 32 elements.

00:58:23 Hence, following 121, there would be 32 elements

00:58:26 ending at 153, if I haven't made a mistake in arithmetic.

00:58:31 And then at 154,

00:58:33 you'd go back up into the body of the periodic table again

00:58:37 and put that under rutherfordium, element 104,

00:58:41 and then go across to element 168,

00:58:44 which would be the next noble gas.

00:58:46 Actually, noble liquid,

00:58:48 because it is predicted that it would have

00:58:51 a boiling point above room temperature.

00:58:54 But I want to make it very clear

00:58:58 that although we understand

00:59:00 that this would be the form of the periodic table,

00:59:03 if the elements were stable, they are not.

00:59:07 The nucleus determines the existence or lack of existence.

00:59:11 The instability of the nucleus determines the existence

00:59:14 or the lack of existence of an element

00:59:16 or the capability of it being synthesized.

00:59:19 And I don't think it'll be possible

00:59:21 to go up to these very heavy elements

00:59:24 that I have just described

00:59:26 and that the furthest that we'll be able to go

00:59:29 is up to element 114 or that region,

00:59:33 which is the island of stability

00:59:36 that we've been trying to reach

00:59:38 during the last 20 years or so.

00:59:40 I think we'll reach it.

00:59:42 You talk about the table in a largely predictive way.

00:59:45 Yes.

00:59:46 And that's what Mendeleev did.

00:59:48 Was that his great contribution?

00:59:50 Yes. The great contribution of Mendeleev

00:59:53 was that he used the table

00:59:58 to predict the chemical properties

01:00:02 of missing elements,

01:00:05 making it possible for people to go out

01:00:08 and discover them in nature.

01:00:10 That's what set him apart from others

01:00:13 who had also made unifying compilations.

01:00:18 He, of course, in a sense,

01:00:21 profited from the unifications

01:00:24 that had been made up to that time.

01:00:26 But his big contribution was

01:00:29 that he put it in a form

01:00:31 where he could find gaps

01:00:34 that represented elements

01:00:39 whose chemical properties he could predict,

01:00:43 and then he stuck his neck out

01:00:45 and predicted precisely those chemical properties.

01:00:49 That's where Mendeleev stood out,

01:00:51 and that's why he is given essentially,

01:00:56 well, most of the credit

01:00:58 for the discovery of the periodic table principle.

01:01:01 And today are you continuing?

01:01:03 Well, today scientists are continuing

01:01:05 to extend it at the upper end.

01:01:08 And as I've indicated,

01:01:11 we think we know what form it would take

01:01:15 on through the superactinide elements

01:01:17 up to element 168,

01:01:19 even though it probably will never be possible on Earth,

01:01:24 maybe out in the stars or neutron stars or somewhere,

01:01:27 these might be synthesized.

01:01:30 But we think we understand

01:01:33 the form that the periodic table would take

01:01:37 if the elements were stable enough

01:01:39 to be synthesized and observed.

01:01:42 And by the way,

01:01:44 this has all been confirmed

01:01:47 by high-speed calculations

01:01:50 with the powerful computers that are available now.

01:01:54 The principles of atomic structure

01:01:56 are so well understood

01:01:58 that it is possible through what is called

01:02:01 ab-initial, you know,

01:02:03 fundamental calculations

01:02:06 based on sound theory

01:02:08 to predict mathematically

01:02:11 the way these electrons fill in

01:02:13 as you go to these heavier elements

01:02:16 up to that with the atomic number 168.

01:02:19 And these confirm this general outline

01:02:22 that I've just given,

01:02:24 including the place at which

01:02:27 the superactinide elements

01:02:29 with the atomic numbers

01:02:31 122 to 153 inclusive

01:02:34 will find their places in the periodic table.

01:02:38 And finally,

01:02:43 perhaps you could just say something about

01:02:46 the fact that, as I understand it,

01:02:49 and the periodic table is a human construction,

01:02:52 but it's not a classification like clinic.

01:02:55 I mean, it's this,

01:02:57 these elements exist throughout the universe

01:03:01 and they're the same.

01:03:03 I mean, something with 26 protons in its nucleus is iron,

01:03:06 whether we're on Earth or whether we're

01:03:08 unimaginably far away.

01:03:10 Perhaps you could just make a general statement

01:03:13 that this represents

01:03:17 a universal phenomenon.

01:03:20 And secondly,

01:03:25 do some of these,

01:03:27 do you think superelements exist somewhere else?

01:03:35 The question has arisen, of course,

01:03:37 whether some of these elements exist

01:03:40 in nature or somewhere else in the universe.

01:03:44 They undoubtedly,

01:03:46 up to a rather large atomic number,

01:03:49 existed at the beginning of time

01:03:51 when the elements were synthesized

01:03:54 in the nuclear reactions

01:03:56 and the supernovae and the stars and so forth.

01:04:00 But due to their half-lives,

01:04:02 which we now well understand,

01:04:04 they have decayed in the meantime.

01:04:06 With one exception,

01:04:08 there is an isotope of plutonium

01:04:12 with the mass number 244.

01:04:14 The famous plutonium that's used in nuclear energy

01:04:17 is plutonium-239.

01:04:19 It has a half-life of 30,000 years,

01:04:21 therefore, of course, it has decayed.

01:04:25 Well, if I can digress a moment,

01:04:27 except that it's synthesized

01:04:30 in uranium ores wherever there are neutrons,

01:04:33 just like it is synthesized in a nuclear reactor.

01:04:35 So there's a little plutonium-239

01:04:37 in all uranium deposits,

01:04:39 you know, one part in 10 to the 12th,

01:04:41 one part in a million million.

01:04:43 But there is another isotope, plutonium-244,

01:04:47 that has a half-life of about 80 million years.

01:04:53 And that means that in terms

01:04:58 of the age of the Earth,

01:05:02 you can calculate that there would be

01:05:06 maybe one part in 10 to the 20th

01:05:09 in a uranium ore

01:05:11 or where it might occur

01:05:14 still left on Earth

01:05:17 if it were present in the primordial form,

01:05:20 just from the decay

01:05:23 according to its known half-life.

01:05:25 And there is a scientist, Darlene Hoffman,

01:05:29 and her co-workers about nearly 20 years ago

01:05:35 looked for this and found plutonium-244

01:05:38 to the extent of about one part in 10 to the 20th.

01:05:41 So that in that sense,

01:05:43 plutonium is one of the natural elements.

01:05:46 But it's, you know, it's just sort of a stunt

01:05:48 in order to find that.

01:05:57 The principle of the periodic table, of course,

01:06:00 is as it has turned out,

01:06:02 Mandalayev didn't understand it at that time in 1869,

01:06:06 is that as you build up the elements

01:06:09 by adding more protons in the nucleus

01:06:12 and, of course, compensating electrons,

01:06:14 extra nuclear electrons,

01:06:16 you reach closed shells.

01:06:19 That's at the noble gases.

01:06:21 And then when you finish a closed shell,

01:06:24 you begin to put electrons outside of that shell

01:06:27 and then you go back over to the left-hand side

01:06:30 and that's an alkali metal.

01:06:32 And then you go on across again

01:06:34 until you reach another closed shell.

01:06:36 But as you go further and further down in the periodic table,

01:06:39 you get more and more electron shells

01:06:42 until you get to the lanthanides

01:06:44 where you have to fill in the 14f electrons

01:06:47 and the actinides, the 14f electrons and so forth.

01:06:51 So it is the closed shells.

01:06:53 And that's what really leads us to predict,

01:06:57 by analogy and also by calculation

01:07:00 involving the principles of nuclear structure,

01:07:03 closed shells in the nucleus,

01:07:06 closed proton shells

01:07:08 and closed neutron shells

01:07:10 that lead to increased stability,

01:07:13 giving us the concept

01:07:15 that there should be increased stability

01:07:17 at 114 protons.

01:07:19 And, by the way, 184 neutrons.

01:07:22 The idea of closed shells

01:07:25 leading to tighter binding

01:07:30 and sort of a satisfaction in the nucleus

01:07:37 or in the atom

01:07:41 with the completion

01:07:45 of a certain amount of basic nuclear structure

01:07:49 or electronic structure.

01:07:51 Is it exciting when a new element is discovered?

01:07:54 It has been and still is exciting

01:07:58 when a new element is discovered.

01:08:03 A number of them have been discovered at Berkeley

01:08:07 over the years.

01:08:09 Two of them in the huge hydrogen bomb explosion,

01:08:13 elements 99 and 100.

01:08:15 That was particularly exciting.

01:08:17 If you were to ask me which one was the most exciting

01:08:20 or which ones,

01:08:22 I would have to say elements 95 and 96

01:08:25 because of the involvement with my prediction

01:08:29 and the ultimate proving of my actinide hypothesis

01:08:33 as it was called in those days.

01:08:35 I call it the actinide concept now.

01:08:38 Although, of course, the discovery of plutonium

01:08:41 was exciting too, particularly since we,

01:08:46 after finding another isotope,

01:08:49 very soon found the plutonium-239

01:08:52 and proved that it was fissionable with slow neutrons,

01:08:55 hence making it clear that it was eligible,

01:08:58 if we could learn how to manufacture it,

01:09:01 which we did during the war in the Manhattan Project,

01:09:04 eligible as a source of huge amounts of nuclear energy.

01:09:09 You talk about 104 a lot.

01:09:12 Are you looking forward to that one being discovered?

01:09:15 114, I'm afraid.

01:09:17 Yes, we are trying very hard at Berkeley,

01:09:23 at the German laboratory, GSI, near Darmstadt,

01:09:27 and the scientists in the Soviet Union

01:09:32 at the Dubna Laboratory.

01:09:34 I haven't had time to go into the fact

01:09:37 that there's some controversy about the discovery.

01:09:40 I think I alluded to this,

01:09:42 but the scientists in the Dubna Laboratory,

01:09:45 who are often co-workers,

01:09:47 have made competing claims to the discovery

01:09:52 of element 104 and 105,

01:09:54 and even suggest other names,

01:09:57 and also contest us on the discovery of 106,

01:10:01 and are contesting the Germans

01:10:03 on the discovery of elements 107, 108, and 109.

01:10:06 I may be biased.

01:10:08 They base all of their claims to the discovery

01:10:11 on the production of an isotope

01:10:13 that decays by spontaneous fission,

01:10:15 which is a non-definitive process.

01:10:18 All spontaneous fissions,

01:10:20 that is a decay where the element splits roughly in half,

01:10:24 look alike,

01:10:26 and there is no way of really establishing

01:10:29 the atomic number of a new element that way,

01:10:34 whereas the method of genetic relationships,

01:10:37 which has been used by our people at Berkeley,

01:10:39 and now the people in Germany,

01:10:41 tie it to a previously known daughter or granddaughter,

01:10:45 so that it is absolutely certain

01:10:48 what the atomic number of a parent is

01:10:53 if it decays by the emission of an alpha particle,

01:10:56 which is two neutrons and two protons.

01:10:58 It's just a matter of adding it up

01:11:00 from the atomic number and the mass number of the daughter.

01:11:04 So there is this controversy,

01:11:06 and because of this,

01:11:08 the International Union of Pure and Applied Chemistry

01:11:11 has suggested what I think is an atrocious scheme

01:11:16 for naming undiscovered elements,

01:11:20 or all the elements for that matter,

01:11:22 beyond element 103,

01:11:24 and thus for element 104.

01:11:27 These, they claim, are temporary names,

01:11:30 but I think they shouldn't even be honored

01:11:33 with a temporary status,

01:11:35 because it's so silly.

01:11:37 They suggest using names like,

01:11:40 like for element 104,

01:11:43 uni-nil-quadium,

01:11:46 and so that the symbol becomes u-n-q.

01:11:51 And the ultimate absurdity is,

01:11:55 for example, for element 111,

01:11:57 that would be uni-uni-uni,

01:12:00 and the element would be u-u-u,

01:12:02 or u-u-u, I don't know what.

01:12:04 And this is met with ridicule

01:12:08 by all the people working in the field.

01:12:11 And we deplore the fact that this gets on

01:12:15 a number of periodic tables throughout the country

01:12:18 and throughout the world,

01:12:19 and even into a number of the books.

01:12:21 And we're doing our best to counteract that.

01:12:24 The way to refer to undiscovered elements

01:12:27 is by their atomic number.

01:12:29 If you need to write the formula for element 111,

01:12:33 just write 111.

01:12:35 And if you need it in a formula,

01:12:37 just put 111 and put parenthesis around it,

01:12:40 and then if it's an oxide,

01:12:42 say O or O2 or whatever you wish.

01:12:45 You don't have to have u-u-u, O2.

01:12:48 It's just silly.

01:12:50 And we're very distressed that

01:12:55 such a scheme has found its way

01:12:58 into the chemistry books

01:13:01 and the periodic tables.

01:13:25 I refer to this as my periodic table tie.

01:13:29 It was given to me by a high school teacher.

01:13:32 I use it in my talks about the periodic table

01:13:37 and the transuranium elements.

01:13:39 I facetiously suggest that I can use it as a crib

01:13:45 in case I forget the position of these elements.

01:13:50 Of course, someone has suggested that

01:13:53 with the new elements,

01:13:56 the additional elements that are now known,

01:13:58 I should extend it.

01:13:59 The heaviest one here is thermium,

01:14:02 and I should extend it on down.

01:14:05 But I like to reply that if I did that,

01:14:08 it might be so long that I would step on it

01:14:11 and it would not be feasible.

01:14:14 I wish it...

01:14:15 It's actually a commercial tie.

01:14:17 I think it's a rooster-type commercial brand.

01:14:26 I wish I could find a place to buy more of them

01:14:29 because it is so popular

01:14:32 and I would like to use it as a gift.

01:14:45 I like to refer to this as my periodic table tie.

01:14:48 It was given to me by a high school teacher

01:14:51 at one of my talks.

01:14:53 I use it, I wear it usually

01:14:56 during my talks on the periodic table

01:14:59 and the transuranium elements

01:15:00 and facetiously suggest that this is my crib.

01:15:04 I can refer to it in case I forget

01:15:07 where these elements fit into the periodic table.

01:15:11 You notice that it ends at thermium.

01:15:15 Of course, now we have more elements

01:15:17 and the suggestion has been made

01:15:19 that I should have it extended

01:15:22 and I jokingly reply,

01:15:25 well, if I did that, it might be so long

01:15:27 that I would step on it

01:15:28 and it wouldn't be feasible.

01:15:38 No, it's okay.

01:15:39 We don't have to re-record this

01:15:40 with the other microphone.

01:15:51 Okay.

01:16:21 Okay.

01:16:51 Yeah, I see.

01:16:57 So do I.

01:16:58 I think so.

01:16:59 So do I.

01:17:00 Okay.

01:17:13 I've been in Berkeley.

01:17:14 I used to be.

01:17:16 I've never been in Berkeley, though.

01:17:18 But they couldn't find any members,

01:17:20 so it's just that.

01:17:21 Maybe it was called mock room.

01:17:26 Maybe it was.

01:17:27 Maybe it was.

01:17:30 I mean, my father was always

01:17:32 in the third show,

01:17:33 and I was in the last two shows.

01:17:35 Somehow, I was the last person in the second show.

01:17:38 So that was a mock room.

01:17:40 And you immigrated to the United States, right?

01:17:43 Yes, I moved five or three times.

01:17:45 Yes, I did.

01:17:46 I see.

01:17:47 So all you have to do is get rid of your exes.

01:17:49 Yeah.

01:18:10 I just wanted to budge.

01:18:18 Can I snuck?

01:18:21 Sure.

01:18:22 Basically.

01:18:23 I'm sure it's not going to change.

01:18:26 Do we need to be a little wider?

01:18:28 So we see this.

01:18:31 Okay.

01:18:33 Yeah.

01:18:34 Can Josh do that for you?

01:18:41 I don't like his arm.

01:18:43 See, I've got to have about ten seconds for Josh.

01:18:47 Can I move it a little still?

01:18:49 No.

01:18:50 Okay.

01:18:51 So that's going to have to come up to connect.

01:18:53 I'll put it back.

01:18:55 You see, it'll come up like so.

01:18:57 Okay, wait.

01:18:58 And then back away.

01:18:59 Let's start it.

01:19:00 So just stay still now.

01:19:06 Everybody just hold on.

01:19:10 All right, put your first electrode on.

01:19:21 Second electrode on.

01:19:30 Can you turn it on?

01:19:39 Okay, go ahead and do your action.

01:19:50 Turn it on.

01:19:53 Do it again.

01:19:58 And can you do it from the bottom, too?

01:20:01 Or is it the other direction?

01:20:03 Take your hand out and spray it.

01:20:05 Bring it back down and then do it again.

01:20:07 I'm not sure if it works this way.

01:20:24 I think you could close that cover and use it.

01:20:26 Yeah, I need to take a peek.

01:20:28 Let me do the top one again.

01:20:30 Show the next picture.

01:20:37 Okay.

01:20:43 Yeah, bring it in now.

01:20:45 Bring your hand back and do it fairly quickly, two or three times across the top.

01:21:02 Okay.

01:21:03 Do our closeness.

01:21:05 Can you do it from the bottom, by the way?

01:21:07 Or do we have to do it?

01:21:09 Would you roll it?

01:21:10 No, I'm rolling it up.

01:21:11 Oh, okay.

01:21:12 So do the top one.

01:21:30 Do the bottom.

01:21:36 But can you do the bottom so that it forces it to go up to the top?

01:21:41 Okay.

01:21:48 There.

01:21:50 There.

01:21:52 There.

01:21:54 Bring it down quite quickly.

01:21:57 No, keep it the way you have it.

01:22:00 Keep it the way you have it.

01:22:02 Because you can see it a lot better if you're forcing it up.

01:22:08 Let it come back to normal.

01:22:11 Force it back up.

01:22:19 Now, can we have it come towards the bar?

01:22:22 Take your hand out in front of you.

01:22:25 Are we trying to do it?

01:22:26 Either or, both sides.

01:22:29 Over?

01:22:30 Yeah.

01:22:38 Same thing on the top.

01:22:49 I'm losing it now.

01:22:51 No, I have to play around with it.

01:22:58 Just diffuse everything.

01:23:02 Oh, but you're not pulling it towards the bar?

01:23:05 No.

01:23:09 Okay, let's shoot.

01:23:11 Where do you need to be?

01:23:12 Positive angle.

01:23:13 You might have to do that first.

01:23:16 First, go ahead and just pluck on the inside.

01:23:19 Okay.

01:23:21 Okay.

01:23:27 Move a little further to your right.

01:23:30 All the way.

01:23:32 There.

01:23:34 Go back and do that two or three times.