1
00:00:00,030 --> 00:00:02,400
The following content is
provided under a Creative

2
00:00:02,400 --> 00:00:03,840
Commons license.

3
00:00:03,840 --> 00:00:06,850
Your support will help MIT
OpenCourseWare continue to

4
00:00:06,850 --> 00:00:10,520
offer high-quality educational
resources for free.

5
00:00:10,520 --> 00:00:13,390
To make a donation or view
additional materials from

6
00:00:13,390 --> 00:00:17,490
hundreds of MIT courses, visit
MIT OpenCourseWare at

7
00:00:17,490 --> 00:00:18,740
ocw.mit.edu.

8
00:00:21,020 --> 00:00:22,880
Tuesday will be the
first weekly quiz,

9
00:00:22,880 --> 00:00:25,170
celebration that is.

10
00:00:25,170 --> 00:00:26,790
That will be at the beginning
of recitation.

11
00:00:26,790 --> 00:00:28,620
You'll have 10 minutes.

12
00:00:28,620 --> 00:00:31,270
It'll be a short one-pager.

13
00:00:31,270 --> 00:00:33,170
You just write on the page.

14
00:00:33,170 --> 00:00:36,560
All you bring is your periodic
table, which you should have

15
00:00:36,560 --> 00:00:38,250
gotten in recitation
yesterday.

16
00:00:38,250 --> 00:00:42,190
Periodic Table, table of
constants, calculator,

17
00:00:42,190 --> 00:00:47,000
something to write with, but no
aid sheet on the weeklies.

18
00:00:47,000 --> 00:00:49,910
Readings: Readings,
I urge you to read

19
00:00:49,910 --> 00:00:51,720
before you come to class.

20
00:00:51,720 --> 00:00:54,680
And so if you go to the
website, you can go to

21
00:00:54,680 --> 00:00:57,560
Schedule, and in the schedule,
you'll see stuff like this

22
00:00:57,560 --> 00:01:01,860
that tells you what the readings
are for the day.

23
00:01:01,860 --> 00:01:04,640
As I mentioned last day,
the lectures are being

24
00:01:04,640 --> 00:01:09,990
videographed and posted probably
within an hour on the

25
00:01:09,990 --> 00:01:15,630
website and any of the images
that I show are also recorded,

26
00:01:15,630 --> 00:01:18,150
burned as PDFs and uploaded.

27
00:01:18,150 --> 00:01:23,640
So you don't have to be put in
high-speed stenographic mode

28
00:01:23,640 --> 00:01:27,160
in order to attend class.

29
00:01:27,160 --> 00:01:29,260
What's the other thing
I wanted to tell you?

30
00:01:29,260 --> 00:01:32,340
If you're new to the class or
if you need to change your

31
00:01:32,340 --> 00:01:36,820
recitation section because your
conditions have changed,

32
00:01:36,820 --> 00:01:39,780
do not simply go to
the other class.

33
00:01:39,780 --> 00:01:41,350
We're trying to regulate
enrollment,

34
00:01:41,350 --> 00:01:42,680
particularly on Tuesdays.

35
00:01:42,680 --> 00:01:46,740
If the TA shows up expecting 20
students and has 20 copies

36
00:01:46,740 --> 00:01:49,950
of the quiz and 25 people
show up, that's not

37
00:01:49,950 --> 00:01:51,240
a recipe for success.

38
00:01:51,240 --> 00:01:54,510
So you must go to my
administrative assistant,

39
00:01:54,510 --> 00:01:57,300
Hilary Sheldon in order
to change recitation.

40
00:01:57,300 --> 00:01:59,830
And if you need any of the
handouts and so on, it's just

41
00:01:59,830 --> 00:02:04,740
down the hall here in Building
8, Room 201.

42
00:02:04,740 --> 00:02:06,720
I think that's all that
I had to say.

43
00:02:06,720 --> 00:02:09,160
If you go here the videos
are all listed.

44
00:02:09,160 --> 00:02:14,040
So last day we started talking
about taxonomy and that led us

45
00:02:14,040 --> 00:02:16,270
to the beginnings of
atomic theory.

46
00:02:16,270 --> 00:02:19,790
We visited with Democritus,
400 BC.

47
00:02:19,790 --> 00:02:22,790
We had that detour with the
idiocy of Aristotle, and then

48
00:02:22,790 --> 00:02:26,510
eventually got back to our
senses, and we saw John Dalton

49
00:02:26,510 --> 00:02:30,540
with his table of the elements,
and then ultimately

50
00:02:30,540 --> 00:02:32,260
onto Mendeleyev.

51
00:02:32,260 --> 00:02:35,240
And I wanted to pick up
the thread there.

52
00:02:35,240 --> 00:02:38,390
But before doing so, draw
attention the fact that John

53
00:02:38,390 --> 00:02:42,900
Dalton did more than simply
develop a set of fonts for us.

54
00:02:42,900 --> 00:02:46,090
So he proposed the model of the
atom and this goes back

55
00:02:46,090 --> 00:02:50,440
little over 200 years ago,
and these are the

56
00:02:50,440 --> 00:02:52,120
features of the model.

57
00:02:52,120 --> 00:02:54,680
First of all, that matter is
composed of atoms that are

58
00:02:54,680 --> 00:02:56,360
indivisible and indestructible.

59
00:02:56,360 --> 00:02:57,560
So that goes all
the way back to

60
00:02:57,560 --> 00:03:00,780
Democritus, nothing new there.

61
00:03:00,780 --> 00:03:02,685
All atoms of an element
are identical.

62
00:03:05,240 --> 00:03:08,330
Atoms of different elements
have different weights and

63
00:03:08,330 --> 00:03:09,550
different chemical properties.

64
00:03:09,550 --> 00:03:12,170
This is the emergence of modern
material science, the

65
00:03:12,170 --> 00:03:15,410
connection between properties
and elements.

66
00:03:15,410 --> 00:03:18,900
So the weight arguably is one
of the properties, but the

67
00:03:18,900 --> 00:03:20,910
only way they could distinguish
elements at that

68
00:03:20,910 --> 00:03:24,890
time was by their atomic mass.

69
00:03:24,890 --> 00:03:28,110
Atoms of different elements
combine in simple whole-number

70
00:03:28,110 --> 00:03:30,600
ratios to form compounds.

71
00:03:30,600 --> 00:03:33,120
Well, that makes sense because
they're the elements.

72
00:03:33,120 --> 00:03:34,750
They are the elemental
building blocks.

73
00:03:34,750 --> 00:03:39,690
If I told you you could build a
structure made of blocks and

74
00:03:39,690 --> 00:03:41,720
part-way through your
construction I say, why don't

75
00:03:41,720 --> 00:03:44,210
you cut that block in half,
you'd say, well, then the

76
00:03:44,210 --> 00:03:46,510
block isn't the building
block.

77
00:03:46,510 --> 00:03:48,730
It's the half-block that's
the building block.

78
00:03:48,730 --> 00:03:52,650
So axiomatically if these are
the elements they must combine

79
00:03:52,650 --> 00:03:55,650
in simple whole-number ratios
to form compounds.

80
00:03:55,650 --> 00:03:58,600
And lastly, atoms cannot be
created or destroyed.

81
00:03:58,600 --> 00:04:01,180
Well, he wasn't foretelling
E equals mc squared.

82
00:04:01,180 --> 00:04:03,700
What he was saying was that if
you take elements and you

83
00:04:03,700 --> 00:04:06,620
combine them to form a compound,
if you subsequently

84
00:04:06,620 --> 00:04:08,510
decompose the compound
you get the elements

85
00:04:08,510 --> 00:04:10,690
back as they were.

86
00:04:10,690 --> 00:04:16,250
So those are the features
of John Dalton's model.

87
00:04:16,250 --> 00:04:18,780
And we fast forward to 1869.

88
00:04:18,780 --> 00:04:22,520
And this is the knowledge that
was available at the time in

89
00:04:22,520 --> 00:04:25,380
terms of the elements that
had been isolated and

90
00:04:25,380 --> 00:04:26,500
characterized.

91
00:04:26,500 --> 00:04:28,220
And it was with this
set of elements

92
00:04:28,220 --> 00:04:30,410
that Mendeleyev operated.

93
00:04:30,410 --> 00:04:34,250
On file cards, in his breast
pocket, he carried with him

94
00:04:34,250 --> 00:04:35,150
everywhere.

95
00:04:35,150 --> 00:04:37,760
And he wrote down the names of
the elements and their atomic

96
00:04:37,760 --> 00:04:42,620
masses and their properties and
whatever else he could use

97
00:04:42,620 --> 00:04:44,510
the way of characterizing
them.

98
00:04:44,510 --> 00:04:46,620
And during the course of
writing a textbook--

99
00:04:46,620 --> 00:04:50,250
he had just finished a chapter
on the alkaline metals and he

100
00:04:50,250 --> 00:04:52,220
was sitting in the railway
station playing

101
00:04:52,220 --> 00:04:53,780
solitaire, and boom!

102
00:04:53,780 --> 00:05:00,110
The flash came to him that you
don't put arsenic underneath

103
00:05:00,110 --> 00:05:03,590
aluminum even though it's next
in mass to zinc. You move it

104
00:05:03,590 --> 00:05:05,470
over and you don't even
put it under silicon.

105
00:05:05,470 --> 00:05:06,840
You put it under phosphorus.

106
00:05:06,840 --> 00:05:09,680
And furthermore, what he said
was there's going to be an

107
00:05:09,680 --> 00:05:13,780
element here discovered under
silicon and it will have these

108
00:05:13,780 --> 00:05:14,410
properties.

109
00:05:14,410 --> 00:05:18,290
And let's look a little bit more
deeply at the properties.

110
00:05:18,290 --> 00:05:23,870
But before doing so I want to
say that by announcing this

111
00:05:23,870 --> 00:05:28,580
prediction of what the element
should be that's missing is

112
00:05:28,580 --> 00:05:31,010
that we start to see the
evolution of principles of

113
00:05:31,010 --> 00:05:31,930
modern chemistry.

114
00:05:31,930 --> 00:05:34,320
First of all, he recognized
the pattern.

115
00:05:34,320 --> 00:05:36,060
So did Lothar Meyer
in Tuebingen.

116
00:05:36,060 --> 00:05:39,090
So they both proposed a
periodic table of the

117
00:05:39,090 --> 00:05:42,320
elements, but where Mendeleyev
pulled away from the pack and

118
00:05:42,320 --> 00:05:44,250
distinguished himself was
that he developed a

119
00:05:44,250 --> 00:05:45,880
quantitative model.

120
00:05:45,880 --> 00:05:48,000
And I haven't shown you the
quantitative aspect yet.

121
00:05:48,000 --> 00:05:49,530
That's coming next.

122
00:05:49,530 --> 00:05:52,020
That explains the observations,
and that's good.

123
00:05:52,020 --> 00:05:53,420
You might say, well,
that's just curve

124
00:05:53,420 --> 00:05:54,880
fitting if you're a cynic.

125
00:05:54,880 --> 00:05:59,440
But it makes predictions that
can be tested by experiment,

126
00:05:59,440 --> 00:06:01,360
tested by experiment.

127
00:06:01,360 --> 00:06:03,430
So let's take a look.

128
00:06:03,430 --> 00:06:06,950
He said that under silicon, but
above tin, there would be

129
00:06:06,950 --> 00:06:07,420
an element.

130
00:06:07,420 --> 00:06:08,680
He called it eka-silicon.

131
00:06:08,680 --> 00:06:11,570
Eka is a Sanskrit word,
which means one after.

132
00:06:11,570 --> 00:06:15,090
So this is the element
one after silicon.

133
00:06:15,090 --> 00:06:19,610
It was eventually isolated and
given the name germanium.

134
00:06:19,610 --> 00:06:21,770
Mendeleyev said it would
have an atomic mass of

135
00:06:21,770 --> 00:06:23,200
72 grams per mole.

136
00:06:23,200 --> 00:06:25,640
In fact, it's 72.59.

137
00:06:25,640 --> 00:06:28,510
He said it would have a density
of 5.5 grams per cubic

138
00:06:28,510 --> 00:06:29,060
centimeter.

139
00:06:29,060 --> 00:06:30,870
It's 5.36.

140
00:06:30,870 --> 00:06:33,462
This is 1869.

141
00:06:33,462 --> 00:06:35,940
He said that it would have a
high melting point, whatever

142
00:06:35,940 --> 00:06:39,520
that means, and it melts
at 958 Celsius.

143
00:06:39,520 --> 00:06:40,430
It's compounds.

144
00:06:40,430 --> 00:06:43,750
he said it would form a dioxide
with a high melting

145
00:06:43,750 --> 00:06:45,660
point and a density of 4.7.

146
00:06:45,660 --> 00:06:49,590
It forms a dioxide and
its density is 4.70.

147
00:06:49,590 --> 00:06:53,430
In fact, there's a story about a
French mineralogist who came

148
00:06:53,430 --> 00:06:57,050
upon some of the stuff that
ultimately became germanium

149
00:06:57,050 --> 00:07:01,200
dioxide, measured its density
and reported it to Mendeleyev

150
00:07:01,200 --> 00:07:03,750
in a letter, saying, you know I
measured the stuff and it's

151
00:07:03,750 --> 00:07:05,880
5.3 grams per cubic
centimeter.

152
00:07:05,880 --> 00:07:07,960
Mendeleyev wrote him back
and he said, make

153
00:07:07,960 --> 00:07:08,780
the measurement again.

154
00:07:08,780 --> 00:07:09,630
You're wrong.

155
00:07:09,630 --> 00:07:11,770
He wrote back three months
later and said,

156
00:07:11,770 --> 00:07:12,870
I measured it again.

157
00:07:12,870 --> 00:07:14,620
It's 4.7.

158
00:07:14,620 --> 00:07:17,055
That was the genius
of Mendeleyev.

159
00:07:17,055 --> 00:07:20,330
To go way out on a limb and
make those predictions.

160
00:07:20,330 --> 00:07:23,960
And so I've made the case for
the table of the elements.

161
00:07:23,960 --> 00:07:25,910
Why do we call it the
Periodic Table?

162
00:07:25,910 --> 00:07:27,310
What's the periodic about?

163
00:07:27,310 --> 00:07:28,490
Well, the periodic--

164
00:07:28,490 --> 00:07:31,430
take a look here, if you go to
the website there's a tab

165
00:07:31,430 --> 00:07:35,040
called Courseware and there's
a tab called Periodic Table.

166
00:07:35,040 --> 00:07:39,450
And you can go to the Periodic
Table and ask the software to

167
00:07:39,450 --> 00:07:40,810
plot property.

168
00:07:40,810 --> 00:07:44,470
So for example this is boiling
point versus proton number or

169
00:07:44,470 --> 00:07:45,690
atomic number.

170
00:07:45,690 --> 00:07:48,630
And so you see the boiling point
varies as you move from

171
00:07:48,630 --> 00:07:50,630
low atomic number to
high atomic number.

172
00:07:50,630 --> 00:07:52,110
But it's not totally random.

173
00:07:52,110 --> 00:07:54,290
It's not a Gaussian
distribution.

174
00:07:54,290 --> 00:07:55,280
There are features.

175
00:07:55,280 --> 00:07:58,410
It goes up and down, up,
down, up and down.

176
00:07:58,410 --> 00:08:01,180
If you train your eye a little
bit you'll actually see some

177
00:08:01,180 --> 00:08:03,350
regularity, a pattern there.

178
00:08:03,350 --> 00:08:04,380
Maybe that's not so good.

179
00:08:04,380 --> 00:08:05,100
Let's look at this one.

180
00:08:05,100 --> 00:08:06,620
This is electrical
conductivity.

181
00:08:06,620 --> 00:08:10,680
And again, up, down, up, down
and look at those red lines.

182
00:08:10,680 --> 00:08:11,880
There, there, there, there.

183
00:08:11,880 --> 00:08:12,760
Don't you see something?

184
00:08:12,760 --> 00:08:14,020
That's a pattern.

185
00:08:14,020 --> 00:08:16,690
And they're almost
equally spaced.

186
00:08:16,690 --> 00:08:20,720
So that was where Mendeleyev
announced his Periodic Law,

187
00:08:20,720 --> 00:08:24,520
where he said the properties are
related to the identity of

188
00:08:24,520 --> 00:08:29,930
the atoms. And furthermore, he
announced, that the properties

189
00:08:29,930 --> 00:08:33,870
are a periodic variation
in atomic mass.

190
00:08:33,870 --> 00:08:44,320
So let's get that now
Mendeleyev's Periodic Law, and

191
00:08:44,320 --> 00:08:57,220
the properties of the
elements vary

192
00:08:57,220 --> 00:09:04,960
periodically with atomic mass.

193
00:09:08,040 --> 00:09:09,290
That was Mendeleyev.

194
00:09:10,940 --> 00:09:17,010
So now that we know that we can
go forward, and here's now

195
00:09:17,010 --> 00:09:21,010
the full-blown Periodic Table
according to the framework

196
00:09:21,010 --> 00:09:22,250
that Mendeleyev established.

197
00:09:22,250 --> 00:09:24,520
Now if you look at this
carefully, you'll see down

198
00:09:24,520 --> 00:09:27,600
here things get whited out
and there's these strange

199
00:09:27,600 --> 00:09:30,000
notations, uu, m, and
all that stuff.

200
00:09:30,000 --> 00:09:30,730
What's that all about?

201
00:09:30,730 --> 00:09:32,210
This is where the super
heavies lie.

202
00:09:32,210 --> 00:09:34,190
These are all synthetic
elements.

203
00:09:34,190 --> 00:09:39,820
Transuranic, they're made by
high-energy reactions,

204
00:09:39,820 --> 00:09:44,250
so-called high-energy physics
in what you might call

205
00:09:44,250 --> 00:09:48,020
accelerators, atom smashers,
what have you.

206
00:09:48,020 --> 00:09:51,360
And there's only three places
on the planet where you can

207
00:09:51,360 --> 00:09:54,340
conduct such reactions.

208
00:09:54,340 --> 00:09:59,510
One of them is in Darmstadt
in Germany.

209
00:09:59,510 --> 00:10:02,860
One is in Dubna, just
outside of Moscow.

210
00:10:02,860 --> 00:10:04,860
And if you want to stay home--

211
00:10:04,860 --> 00:10:07,390
and eschew the frequent flyer
miles-- you can go to

212
00:10:07,390 --> 00:10:08,550
Berkeley, California.

213
00:10:08,550 --> 00:10:11,690
These are the three places where
we have the accelerators

214
00:10:11,690 --> 00:10:17,110
capable of making
such compounds.

215
00:10:17,110 --> 00:10:22,210
And so, take a look carefully
at what the nomenclature is.

216
00:10:22,210 --> 00:10:26,690
The way you name them is by
using these Latin ordinals.

217
00:10:26,690 --> 00:10:29,420
So un, bi, tri, quad
and so on.

218
00:10:29,420 --> 00:10:33,760
So if you wanted to name element
115, it's ununpentium.

219
00:10:33,760 --> 00:10:36,880
You want the ium ending.

220
00:10:36,880 --> 00:10:37,900
And you can make these up.

221
00:10:37,900 --> 00:10:40,730
You could make up element 205
if you want to or whatever.

222
00:10:40,730 --> 00:10:44,540
My favorite is 111 because
that's unununium.

223
00:10:44,540 --> 00:10:49,760
But there they are, so you
can have fun with those.

224
00:10:49,760 --> 00:10:55,870
But with time, the elements are
being named and these have

225
00:10:55,870 --> 00:10:58,420
been synthesized since
your version of

226
00:10:58,420 --> 00:11:00,080
the table was printed.

227
00:11:00,080 --> 00:11:05,080
And so number 110 is named
Darmstadtium in honor of the

228
00:11:05,080 --> 00:11:07,820
team at Darmstadt that
first isolated it.

229
00:11:07,820 --> 00:11:13,570
And number 111 was just named
two years ago and the name is

230
00:11:13,570 --> 00:11:15,250
roentgenium after Wilhelm
Roentgen,

231
00:11:15,250 --> 00:11:18,500
who discovered x-rays.

232
00:11:18,500 --> 00:11:19,940
Now what is it about
discovery?

233
00:11:19,940 --> 00:11:26,060
Well, here's an example of one
such reaction that would give

234
00:11:26,060 --> 00:11:27,650
you an element.

235
00:11:27,650 --> 00:11:31,550
So if we had access to one of
these devices we could take,

236
00:11:31,550 --> 00:11:35,790
for example, lead and nickel and
accelerate them to very,

237
00:11:35,790 --> 00:11:39,740
very high energies.

238
00:11:39,740 --> 00:11:42,790
And then we could make
110, ununilium.

239
00:11:42,790 --> 00:11:49,010
Or now we'll call it
Darmstadtium plus neutron.

240
00:11:49,010 --> 00:11:54,170
And in doing so we've generated
the new element.

241
00:11:54,170 --> 00:11:58,650
But we can't just say we've made
the element and publish.

242
00:11:58,650 --> 00:12:01,470
We have to be able to
characterize it.

243
00:12:01,470 --> 00:12:05,910
Remember the reason that we gave
Cavendish the credit for

244
00:12:05,910 --> 00:12:08,590
discovering hydrogen wasn't that
he's the first to know

245
00:12:08,590 --> 00:12:11,970
that hydrogen exists, but he
isolated it and gave it value.

246
00:12:11,970 --> 00:12:14,120
So if you look at the rest of
the periodic table, you get

247
00:12:14,120 --> 00:12:17,630
things like boiling point,
melting point, density,

248
00:12:17,630 --> 00:12:20,070
electronegativity, first
ionization energy.

249
00:12:20,070 --> 00:12:21,650
There's a lot of information
there.

250
00:12:21,650 --> 00:12:23,000
If you go down here
there's nothing.

251
00:12:23,000 --> 00:12:24,390
It's all blanks.

252
00:12:24,390 --> 00:12:27,810
These things have very,
very short lifetimes.

253
00:12:27,810 --> 00:12:29,230
Fractions of a second.

254
00:12:29,230 --> 00:12:30,530
But you have to isolate them.

255
00:12:30,530 --> 00:12:32,930
There's certain criteria
before you can publish.

256
00:12:32,930 --> 00:12:35,820
And all this is regulated by
this governing body called the

257
00:12:35,820 --> 00:12:38,930
International Union of Pure
and Applied Chemistry, So

258
00:12:38,930 --> 00:12:44,530
UPAC, the organization that
finally rules on the

259
00:12:44,530 --> 00:12:46,240
legitimacy of any of these.

260
00:12:46,240 --> 00:12:48,450
And actually there have been
some retractions in recent

261
00:12:48,450 --> 00:12:50,790
years, where people published
claiming--

262
00:12:50,790 --> 00:12:53,870
I think there was a report out
of Berkeley claiming that

263
00:12:53,870 --> 00:12:57,170
they'd synthesized 115 and then
subsequently that was

264
00:12:57,170 --> 00:13:01,060
retracted because they couldn't
support the property

265
00:13:01,060 --> 00:13:02,870
measurements

266
00:13:02,870 --> 00:13:06,570
Last thing is, if you're
interested, want to do some

267
00:13:06,570 --> 00:13:09,150
extra reading, there's a
fantastic book about

268
00:13:09,150 --> 00:13:09,690
Mendeleyev.

269
00:13:09,690 --> 00:13:13,630
He was the youngest of 14
children, came out of a very

270
00:13:13,630 --> 00:13:18,380
poor family in Siberia and rose
to be a giant of his day.

271
00:13:18,380 --> 00:13:20,490
He was a polymath.

272
00:13:20,490 --> 00:13:23,910
He, among some of the other
things he did, he worked for

273
00:13:23,910 --> 00:13:28,485
the Ministry of Weights and
Measures under the czar.

274
00:13:31,480 --> 00:13:35,270
The czar was interested in
taxation of alcohol.

275
00:13:35,270 --> 00:13:41,150
And if you mix equal volumes of
water and vodka you don't

276
00:13:41,150 --> 00:13:42,420
get additivity.

277
00:13:42,420 --> 00:13:46,460
So 100 mL of water plus 100 mL
of vodka doesn't give 200 mL.

278
00:13:46,460 --> 00:13:47,680
It gives less.

279
00:13:47,680 --> 00:13:52,000
And so Mendeleyev did a study to
determine what the optimum

280
00:13:52,000 --> 00:13:55,280
ratio is so that people couldn't
misrepresent the

281
00:13:55,280 --> 00:13:58,340
amount of alcohol
in the beverage.

282
00:13:58,340 --> 00:14:01,820
And set the standard at 40%
alcohol by volume, which is

283
00:14:01,820 --> 00:14:03,700
used the world over
to this day.

284
00:14:03,700 --> 00:14:08,170
He also came to the United
States in 1876 to go to

285
00:14:08,170 --> 00:14:10,060
Titusville, Pennsylvania,
where the first

286
00:14:10,060 --> 00:14:11,550
oil well was drilled.

287
00:14:11,550 --> 00:14:15,790
And did an exhaustive study
of what was the American

288
00:14:15,790 --> 00:14:17,140
petroleum industry
at the time.

289
00:14:17,140 --> 00:14:19,880
And then went back to Imperial
Russia and did the same survey

290
00:14:19,880 --> 00:14:23,660
for the Czar in Imperial Russia,
including a report

291
00:14:23,660 --> 00:14:26,370
that recommended how to develop
the natural resources

292
00:14:26,370 --> 00:14:27,890
of the time.

293
00:14:27,890 --> 00:14:29,035
He was really an amazing man.

294
00:14:29,035 --> 00:14:31,100
He wrote text books and so on.

295
00:14:31,100 --> 00:14:34,730
And nobody in science--

296
00:14:34,730 --> 00:14:36,890
I would venture to say--
has not heard of

297
00:14:36,890 --> 00:14:38,270
the periodic table.

298
00:14:38,270 --> 00:14:40,010
Mendeleyev died in 1906.

299
00:14:40,010 --> 00:14:42,760
The Nobel Prizes were first
offered in 1901.

300
00:14:42,760 --> 00:14:48,560
So there were five years where
he was close to the top for

301
00:14:48,560 --> 00:14:52,110
winning the Noble Prize but was
eked out by somebody else.

302
00:14:52,110 --> 00:14:53,630
When you look back at
those other Nobel

303
00:14:53,630 --> 00:14:55,450
Prizes, they were deserved.

304
00:14:55,450 --> 00:14:59,170
But none more so than
that for Mendeleyev.

305
00:14:59,170 --> 00:15:04,420
So ironically the man who gave
us seminal knowledge of all

306
00:15:04,420 --> 00:15:07,780
chemistry was never awarded
the Nobel Prize.

307
00:15:07,780 --> 00:15:11,000
And there's probably a lot
of politics in there.

308
00:15:11,000 --> 00:15:14,120
And as I said last day, here's
the typical picture of him.

309
00:15:14,120 --> 00:15:16,280
In this he sort of looks
like a street person,

310
00:15:16,280 --> 00:15:18,590
disheveled and so on.

311
00:15:18,590 --> 00:15:21,780
But this was the man that gave
us the periodic table.

312
00:15:21,780 --> 00:15:26,580
That's him at age 35 when he
annunciated the Periodic Law.

313
00:15:26,580 --> 00:15:28,680
So good for him.

314
00:15:28,680 --> 00:15:29,160
Alright.

315
00:15:29,160 --> 00:15:34,720
So now, let's take a look a
little deeper about the

316
00:15:34,720 --> 00:15:36,070
properties of the elements.

317
00:15:36,070 --> 00:15:38,070
How do we understand the
properties of the elements?

318
00:15:38,070 --> 00:15:39,820
For the properties elements
we're going to have to look

319
00:15:39,820 --> 00:15:41,380
inside the atom.

320
00:15:41,380 --> 00:15:43,120
If you did your reading
you undoubtedly

321
00:15:43,120 --> 00:15:44,790
came across this table.

322
00:15:44,790 --> 00:15:48,000
Which at first pass,
deconstructs the atom into

323
00:15:48,000 --> 00:15:50,100
three simple particles:
the electron, the

324
00:15:50,100 --> 00:15:51,690
proton and the neutron.

325
00:15:51,690 --> 00:15:54,220
Here are their symbols,
e, p and n.

326
00:15:54,220 --> 00:15:58,080
And they're distinguished
by charge and mass.

327
00:15:58,080 --> 00:16:02,030
So the electron has charge,
minus 1.6 times 10 to the

328
00:16:02,030 --> 00:16:04,130
minus 19 Coulombs.

329
00:16:04,130 --> 00:16:07,940
And a very low mass: 9.11
times 10 to the minus 31

330
00:16:07,940 --> 00:16:11,360
kilograms. The electronic charge
is balanced by the

331
00:16:11,360 --> 00:16:12,590
protonic charge.

332
00:16:12,590 --> 00:16:14,260
The atom is net neutral.

333
00:16:14,260 --> 00:16:18,060
So the proton has a charge of
plus 1.6 times 10 to the minus

334
00:16:18,060 --> 00:16:19,540
19 Coulombs.

335
00:16:19,540 --> 00:16:22,920
The neutron, as the name
implies, has 0 charge.

336
00:16:22,920 --> 00:16:25,350
The proton and the neutron
have very nearly

337
00:16:25,350 --> 00:16:27,170
equal masses, however.

338
00:16:27,170 --> 00:16:27,530
Right.

339
00:16:27,530 --> 00:16:30,390
And just a word about
the units.

340
00:16:30,390 --> 00:16:35,440
The units here are given
in terms of the Systeme

341
00:16:35,440 --> 00:16:36,640
Internationale.

342
00:16:36,640 --> 00:16:40,140
So when we use the term, C,
capital C is for the Coulomb.

343
00:16:43,230 --> 00:16:45,240
And that's the unit of charge.

344
00:16:45,240 --> 00:16:48,810
And it has an uppercase letter
because it's named after a

345
00:16:48,810 --> 00:16:52,260
scientist. In this case, the
French scientist, Coulomb,

346
00:16:52,260 --> 00:16:55,120
whereas the gram is
not named after a

347
00:16:55,120 --> 00:16:57,790
scientist and so it's lowercase.

348
00:16:57,790 --> 00:17:00,210
And then we can amplify
by powers of three.

349
00:17:00,210 --> 00:17:03,620
So if I want 1,000 of these,
I put a lowercase k here.

350
00:17:03,620 --> 00:17:07,150
If I put an uppercase K, I end
up with the unit Kelvin, which

351
00:17:07,150 --> 00:17:10,180
is the unit of temperature
named after Lord Kelvin.

352
00:17:10,180 --> 00:17:14,880
And all of this is known as
SI units, which is the

353
00:17:14,880 --> 00:17:16,100
International System.

354
00:17:16,100 --> 00:17:19,510
And it's not because the
scientists don't know how to

355
00:17:19,510 --> 00:17:20,970
develop an abbreviation.

356
00:17:20,970 --> 00:17:23,720
This was originally developed
when French was the

357
00:17:23,720 --> 00:17:26,180
international language
of science.

358
00:17:26,180 --> 00:17:31,000
So this is known as the Systeme
Internationale and all

359
00:17:31,000 --> 00:17:32,970
of these units were defined
at that time.

360
00:17:32,970 --> 00:17:40,760
And the term SI sticks
that's the legacy.

361
00:17:40,760 --> 00:17:43,810
All right, so now if we go
to the Periodic Table.

362
00:17:43,810 --> 00:17:48,400
When we start looking at the
elements, we can look at any

363
00:17:48,400 --> 00:17:51,340
entry on the Periodic Table,
and we have the chemical

364
00:17:51,340 --> 00:18:00,260
symbol that I'm designating here
as uppercase X, and this

365
00:18:00,260 --> 00:18:02,620
was originally John Dalton
with the I and the

366
00:18:02,620 --> 00:18:03,890
circle around it.

367
00:18:03,890 --> 00:18:09,520
And about 30 years later the
Swedish scientist Berzelius

368
00:18:09,520 --> 00:18:13,030
suggested that we use neutral
units and so therefore we have

369
00:18:13,030 --> 00:18:16,920
the Latin coming in for many of
the elements, such as iron,

370
00:18:16,920 --> 00:18:19,970
Fe, ferrum, and gold
Au, aurum.

371
00:18:19,970 --> 00:18:23,430
In the upper-left corner,
we have the quality I'm

372
00:18:23,430 --> 00:18:29,780
representing here, A And
A is the mass number.

373
00:18:29,780 --> 00:18:31,960
Some people call it
the atomic weight.

374
00:18:31,960 --> 00:18:34,470
And it is the sum of the
masses of all the

375
00:18:34,470 --> 00:18:35,350
constituents.

376
00:18:35,350 --> 00:18:39,210
So it's the sum of the mass of
the protons, so it's the

377
00:18:39,210 --> 00:18:43,360
proton number plus the
neutron number plus

378
00:18:43,360 --> 00:18:44,390
the electron number.

379
00:18:44,390 --> 00:18:48,330
But since the electron weighs
1/1800 of what these others

380
00:18:48,330 --> 00:18:50,450
weigh, you normally don't
consider this.

381
00:18:50,450 --> 00:18:51,240
It doesn't matter.

382
00:18:51,240 --> 00:18:55,870
So just adding protons plus
neutrons gets you to what we

383
00:18:55,870 --> 00:18:57,290
call the atomic weight.

384
00:18:57,290 --> 00:19:02,420
And then down in the lower left
corner we have Z and Z is

385
00:19:02,420 --> 00:19:03,850
the proton number.

386
00:19:09,070 --> 00:19:13,250
And as the name implies, it's
equal to the number of protons

387
00:19:13,250 --> 00:19:20,200
in the nucleus, which then
equals the number of electrons

388
00:19:20,200 --> 00:19:23,430
outside the nucleus in
the neutral atom.

389
00:19:25,990 --> 00:19:30,360
Now I'm specifying neutral
atom, because it's not

390
00:19:30,360 --> 00:19:32,820
necessary for atoms to be
neutral and we'll take a look

391
00:19:32,820 --> 00:19:36,040
at those in a moment.

392
00:19:36,040 --> 00:19:37,690
A point about redundancy here.

393
00:19:37,690 --> 00:19:40,930
We don't really need the proton
number and the chemical

394
00:19:40,930 --> 00:19:44,840
symbol because the proton
number really defines.

395
00:19:44,840 --> 00:19:47,110
The proton number is like the
Social Security number.

396
00:19:47,110 --> 00:19:53,820
This is the identity
number of the atom.

397
00:19:53,820 --> 00:19:55,180
If we change the the
proton number,

398
00:19:55,180 --> 00:19:58,200
we change its identity.

399
00:19:58,200 --> 00:20:01,360
So for example, I could
write sodium.

400
00:20:01,360 --> 00:20:04,940
Sodium 23 and 11.

401
00:20:04,940 --> 00:20:06,220
I don't need the 11.

402
00:20:06,220 --> 00:20:09,410
11 means it's sodium or
sodium means it's 11.

403
00:20:09,410 --> 00:20:13,080
So I could just write
this as 23 sodium.

404
00:20:13,080 --> 00:20:15,860
So I know it's sodium, that
means it's got 11 protons and

405
00:20:15,860 --> 00:20:18,220
23 minus 11 must be neutrons.

406
00:20:18,220 --> 00:20:20,050
Or if I wanted to be a
smart aleck, I could

407
00:20:20,050 --> 00:20:22,030
write this : 23 11.

408
00:20:22,030 --> 00:20:22,880
That's sodium.

409
00:20:22,880 --> 00:20:25,640
I don't need to put
anything here.

410
00:20:25,640 --> 00:20:29,850
But there's no smart alecks
here, of course.

411
00:20:29,850 --> 00:20:34,980
So for example, we could then
show this reaction as--

412
00:20:34,980 --> 00:20:36,010
this is what?

413
00:20:36,010 --> 00:20:37,520
208.

414
00:20:37,520 --> 00:20:39,720
This is lead, 208.

415
00:20:39,720 --> 00:20:49,050
And nickel, 62 gives us
Darmstadtium with a value of

416
00:20:49,050 --> 00:20:51,900
269 and the neutron is 1.

417
00:20:51,900 --> 00:20:56,450
You can see how these reactions
can be made to go.

418
00:20:56,450 --> 00:21:01,130
Now atoms don't necessarily
have to be net neutral.

419
00:21:01,130 --> 00:21:07,950
We can have something that
is net non-zero charge.

420
00:21:07,950 --> 00:21:14,270
Net non-zero charge on the atom
gives it the term, ion.

421
00:21:14,270 --> 00:21:17,740
Ion is an atom with net
non-zero charge.

422
00:21:17,740 --> 00:21:22,810
And we have two cases where
the atom is net positive.

423
00:21:22,810 --> 00:21:26,110
If the atom is net positive
that's the result of electron

424
00:21:26,110 --> 00:21:27,780
deficiency.

425
00:21:27,780 --> 00:21:29,420
The atom is electron
deficient.

426
00:21:32,020 --> 00:21:35,510
And we term such an
atom the cation.

427
00:21:35,510 --> 00:21:36,750
There's two types of ions.

428
00:21:36,750 --> 00:21:38,100
The cation.

429
00:21:38,100 --> 00:21:41,740
And then we have something
that is net negative.

430
00:21:41,740 --> 00:21:44,280
If it's net negative, it means
it's electron-rich.

431
00:21:44,280 --> 00:21:48,660
That is to say, there are more
electrons than protons and the

432
00:21:48,660 --> 00:21:52,370
net negative ion is
called the anion.

433
00:21:52,370 --> 00:21:53,910
And you can try to
figure out ways.

434
00:21:53,910 --> 00:21:57,120
I sometimes think that cation
has a t, which looks a little

435
00:21:57,120 --> 00:21:59,420
bit like a plus sign.

436
00:21:59,420 --> 00:22:03,960
Anion has five letters, minus
has five letters.

437
00:22:03,960 --> 00:22:06,980
And they both end in n, but
this has an n, which is

438
00:22:06,980 --> 00:22:07,700
negative or something.

439
00:22:07,700 --> 00:22:08,950
You'll figure something out.

440
00:22:13,210 --> 00:22:16,420
Now we've talked about
varying charge at

441
00:22:16,420 --> 00:22:19,300
constant proton number.

442
00:22:19,300 --> 00:22:21,750
But the other thing we can
do is we can look at--

443
00:22:21,750 --> 00:22:27,640
you can vary the
neutron number.

444
00:22:27,640 --> 00:22:30,050
Since the neutron has no
charge you can vary the

445
00:22:30,050 --> 00:22:32,350
neutron number and not harm the
identity and still have a

446
00:22:32,350 --> 00:22:32,980
neutral atom.

447
00:22:32,980 --> 00:22:41,690
So vary neutron number at
constant proton number.

448
00:22:41,690 --> 00:22:45,030
And let's see what that is.

449
00:22:45,030 --> 00:22:48,220
That gives you something
that looks like this.

450
00:22:48,220 --> 00:22:52,480
So for example, if you if you
look at carbon, the atomic

451
00:22:52,480 --> 00:22:56,100
mass that's shown
here is 12.011.

452
00:22:56,100 --> 00:22:58,550
And you'd say, well, gee, if
it's got 6 neutrons and 6

453
00:22:58,550 --> 00:23:01,130
protons, why isn't
that 12 exactly?

454
00:23:01,130 --> 00:23:03,640
Well, this is the answer here.

455
00:23:03,640 --> 00:23:05,840
You can vary the neutron
number at

456
00:23:05,840 --> 00:23:07,160
constant proton number.

457
00:23:07,160 --> 00:23:11,101
So let's take a look at
how that plays out.

458
00:23:11,101 --> 00:23:14,660
The way that plays out
is as following.

459
00:23:14,660 --> 00:23:16,930
Let's see I'm going to make
a little table here.

460
00:23:24,580 --> 00:23:29,130
So we'll start with carbon 12.

461
00:23:29,130 --> 00:23:31,290
Carbon 12, so that means--

462
00:23:31,290 --> 00:23:32,035
now I know what I'm
going to do.

463
00:23:32,035 --> 00:23:37,820
I'm going to bring this down and
make some headings for me.

464
00:23:37,820 --> 00:23:40,230
This will be my proton
number and this will

465
00:23:40,230 --> 00:23:43,230
be my neutron number.

466
00:23:43,230 --> 00:23:45,180
And finally I'm going
to talk about

467
00:23:45,180 --> 00:23:46,990
abundance, natural abundance.

468
00:23:49,560 --> 00:23:54,260
So carbon 12, since it's carbon,
axiomatically it must

469
00:23:54,260 --> 00:23:55,850
have 6 protons.

470
00:23:55,850 --> 00:23:59,170
And 12 minus 6 is 6, so
it's got 6 neutrons.

471
00:23:59,170 --> 00:24:02,260
And this is the dominant
form of carbon.

472
00:24:02,260 --> 00:24:05,370
If you took a chemical analysis
of the carbon you'd

473
00:24:05,370 --> 00:24:12,660
find that over 98%, 98.892% of
the carbon atoms that you

474
00:24:12,660 --> 00:24:18,820
examined would be of this
form, carbon 12.

475
00:24:18,820 --> 00:24:22,980
Now there's also carbon 13.

476
00:24:22,980 --> 00:24:25,660
Has to be 6, otherwise
it's not carbon.

477
00:24:25,660 --> 00:24:27,690
That means it's got
7 neutrons.

478
00:24:27,690 --> 00:24:29,110
And it's a minority species.

479
00:24:29,110 --> 00:24:31,530
1.108%.

480
00:24:31,530 --> 00:24:34,490
And then there's a third
form of carbon and

481
00:24:34,490 --> 00:24:36,310
that's carbon 14.

482
00:24:36,310 --> 00:24:40,870
Again, has to be 6 and
it's got 8 neutrons.

483
00:24:40,870 --> 00:24:44,480
And it's found in vanishingly
small quantities, one part in

484
00:24:44,480 --> 00:24:45,900
10 to the 12.

485
00:24:45,900 --> 00:24:50,710
Or we could call it ppt,
parts per trillion.

486
00:24:50,710 --> 00:24:58,010
So this is same atomic number,
same proton number, same Z but

487
00:24:58,010 --> 00:25:03,770
different mass numbers.

488
00:25:03,770 --> 00:25:04,960
Different A's.

489
00:25:04,960 --> 00:25:09,290
So all of these variants of
carbon are found on the same

490
00:25:09,290 --> 00:25:12,120
place, the same spot on
the Periodic Table.

491
00:25:12,120 --> 00:25:15,290
The Greek word for same is iso,
and the word for place is

492
00:25:15,290 --> 00:25:18,370
topo, so these are
called isotopes.

493
00:25:18,370 --> 00:25:22,970
The isotopes of carbon are
species that have identical

494
00:25:22,970 --> 00:25:26,840
proton number but different
neutron number.

495
00:25:26,840 --> 00:25:28,370
How about the units?

496
00:25:28,370 --> 00:25:29,650
What are the units here?

497
00:25:29,650 --> 00:25:32,620
Well, we have to give
some kind of unit.

498
00:25:32,620 --> 00:25:36,790
I've been sort of freely going
around and counting protons as

499
00:25:36,790 --> 00:25:37,740
one and so on.

500
00:25:37,740 --> 00:25:39,440
And here's the standard.

501
00:25:39,440 --> 00:25:48,330
The standard for mass is
defined, and the definition

502
00:25:48,330 --> 00:25:49,720
goes like this.

503
00:25:49,720 --> 00:25:53,220
If you take carbon 12, which we
just introduced to you, and

504
00:25:53,220 --> 00:25:58,580
we say that we're going to
specify a mass of 12.000 grams

505
00:25:58,580 --> 00:26:05,400
exactly for a specified
quantity, in other words, a

506
00:26:05,400 --> 00:26:08,850
specified number of these atoms.
We have to say we'll

507
00:26:08,850 --> 00:26:13,550
take a certain number of these
carbon atoms and specify the

508
00:26:13,550 --> 00:26:16,350
mass of that number
is 12 exactly.

509
00:26:16,350 --> 00:26:23,680
And specified number of
atoms being the mole.

510
00:26:23,680 --> 00:26:25,180
The mole.

511
00:26:25,180 --> 00:26:29,880
And it turns out that the mole
has a value of 6.02 times 10

512
00:26:29,880 --> 00:26:30,900
to the 23rd.

513
00:26:30,900 --> 00:26:33,210
How do they get that number?

514
00:26:33,210 --> 00:26:37,300
A little bit more in the
way of definitions.

515
00:26:37,300 --> 00:26:39,590
It was a concept put forth
by a professor.

516
00:26:39,590 --> 00:26:41,660
So we're going to take some time
on it because we respect

517
00:26:41,660 --> 00:26:45,870
professors, in this class at
least. And so this was a

518
00:26:45,870 --> 00:26:51,400
concept put forth by Professor
Amadeo Avogadro.

519
00:26:51,400 --> 00:26:55,580
Professor Avogadro, who was a
professor of physics at the

520
00:26:55,580 --> 00:27:00,790
University of Turin, Torino.

521
00:27:00,790 --> 00:27:02,651
And he was a contemporary of
John Dalton's and they were

522
00:27:02,651 --> 00:27:04,510
both studying gases.

523
00:27:04,510 --> 00:27:08,560
And it was Avogadro who taught
us that, when you keep the

524
00:27:08,560 --> 00:27:11,860
pressure constant equal volumes
of different gases

525
00:27:11,860 --> 00:27:14,250
contain equal numbers
of molecules.

526
00:27:14,250 --> 00:27:17,980
It doesn't matter if you have
argon, which is by itself

527
00:27:17,980 --> 00:27:21,180
atomic, or we have oxygen, which
is diatomic, or you have

528
00:27:21,180 --> 00:27:25,360
methane, which is CH4, five
atoms making a compound.

529
00:27:25,360 --> 00:27:27,740
Equal pressure, equal
volume, equal

530
00:27:27,740 --> 00:27:29,270
numbers of those species.

531
00:27:29,270 --> 00:27:31,720
So that was Avogadro's Law.

532
00:27:31,720 --> 00:27:33,010
So let's put that down.

533
00:27:33,010 --> 00:27:46,160
At constant pressure equal
volumes of different gases,

534
00:27:46,160 --> 00:27:51,340
contain identical numbers of
atoms. Equal volumes of

535
00:27:51,340 --> 00:28:03,010
different gases contain equal
numbers of molecules.

536
00:28:03,010 --> 00:28:06,280
And here I'm using the term
molecule as a counting unit.

537
00:28:06,280 --> 00:28:08,690
So it could be, strictly
speaking, an atom or it could

538
00:28:08,690 --> 00:28:10,800
be diatomic and so on.

539
00:28:10,800 --> 00:28:11,500
That's what it was.

540
00:28:11,500 --> 00:28:18,710
And out of honor for Avogadro,
we name the number of atoms in

541
00:28:18,710 --> 00:28:20,950
the mole the Avogadro number.

542
00:28:20,950 --> 00:28:25,530
Which I've written 6.02
times 10 to the 23rd.

543
00:28:25,530 --> 00:28:28,220
Now how do we determine
Avogadro's number?

544
00:28:28,220 --> 00:28:30,110
That's an interesting story.

545
00:28:30,110 --> 00:28:34,300
So first of all, we need two
pieces of information.

546
00:28:34,300 --> 00:28:37,440
Because we're going to do this
by the noblest form of

547
00:28:37,440 --> 00:28:39,480
chemistry, electrochemistry.

548
00:28:39,480 --> 00:28:42,210
So the first thing we're going
to do is we're going to look

549
00:28:42,210 --> 00:28:49,090
at the work Michael Faraday
in England.

550
00:28:49,090 --> 00:28:51,190
And what Michael Faraday
did is he studied the

551
00:28:51,190 --> 00:28:53,200
electrodeposition of metal.

552
00:28:53,200 --> 00:28:57,470
And specifically he passed
current through a cell and he

553
00:28:57,470 --> 00:28:59,850
electrodeposited silver.

554
00:28:59,850 --> 00:29:04,210
So he starts with silver plus,
that's silver a cation, and by

555
00:29:04,210 --> 00:29:08,000
the action of electric current
attaches an electron to silver

556
00:29:08,000 --> 00:29:09,790
and renders it neutral.

557
00:29:09,790 --> 00:29:14,820
Silver, which now plates out
onto an electrode and they

558
00:29:14,820 --> 00:29:17,160
measured the mass.

559
00:29:17,160 --> 00:29:21,400
They measured the mass of
silver-plated and they compare

560
00:29:21,400 --> 00:29:26,490
it to the amount of charge
that was passed.

561
00:29:26,490 --> 00:29:27,740
They measured the charge.

562
00:29:30,430 --> 00:29:33,260
And you can get charge, because
you know current.

563
00:29:33,260 --> 00:29:35,990
So charge is simply equal to
the integral of the current

564
00:29:35,990 --> 00:29:36,830
times the time.

565
00:29:36,830 --> 00:29:38,560
You know the current,
that's easy.

566
00:29:38,560 --> 00:29:47,030
And what Faraday found was that
to make what we now know

567
00:29:47,030 --> 00:29:51,940
to be 108 grams of silver, 108
grams of silver, which we're

568
00:29:51,940 --> 00:29:55,010
going to subsequently recognize
as the mole, which

569
00:29:55,010 --> 00:29:58,600
is identical to the amount, the
number of particles in 108

570
00:29:58,600 --> 00:30:02,410
grams of silver, is equal to the
number of particles in 12

571
00:30:02,410 --> 00:30:04,770
grams of carbon.

572
00:30:04,770 --> 00:30:08,690
Sort of an Avogadro-type
harkening.

573
00:30:08,690 --> 00:30:10,330
He found that that is--

574
00:30:10,330 --> 00:30:15,990
the equivalent requires
96,485 Coulombs.

575
00:30:15,990 --> 00:30:20,230
So you can say 1 mole of
electrons gives me 1 mole of

576
00:30:20,230 --> 00:30:24,360
silver, so that's the charge on
1 mole of electrons, where

577
00:30:24,360 --> 00:30:28,210
Coulomb is the elementary
charge, because we know 1

578
00:30:28,210 --> 00:30:35,390
electron per 1 silver
atom deposited.

579
00:30:35,390 --> 00:30:38,620
So now if I know that's a mole
of electrons, I need to find a

580
00:30:38,620 --> 00:30:41,270
charge on one electron, divide
through and I get

581
00:30:41,270 --> 00:30:42,760
the Avogadro number.

582
00:30:42,760 --> 00:30:46,720
And to finish the story we have
to wait about 50 years

583
00:30:46,720 --> 00:30:50,550
and come to the United States,
where it's Robert Millikan,

584
00:30:50,550 --> 00:30:54,170
Robert Millikan at the
University of Chicago doing

585
00:30:54,170 --> 00:30:58,130
the oil drop experiment through
which we learn the

586
00:30:58,130 --> 00:30:59,540
elementary charge.

587
00:30:59,540 --> 00:31:02,550
And here's the cartoon of
the oil drop experiment.

588
00:31:02,550 --> 00:31:04,085
I took this from a
different text.

589
00:31:04,085 --> 00:31:05,940
It's not shown in your text.

590
00:31:05,940 --> 00:31:10,340
So I actually did this
experiment as a sophomore at

591
00:31:10,340 --> 00:31:11,200
the University of Toronto.

592
00:31:11,200 --> 00:31:13,410
They had us repeat some of the
great experiments of physics,

593
00:31:13,410 --> 00:31:14,700
the ones that were accessible,
obviously.

594
00:31:14,700 --> 00:31:18,450
I couldn't do high-energy
physics in an afternoon.

595
00:31:18,450 --> 00:31:20,350
That would have taken me
a little bit longer.

596
00:31:20,350 --> 00:31:21,680
But we did this one.

597
00:31:21,680 --> 00:31:25,010
And so it consists of an
atomizer, sort of a perfume

598
00:31:25,010 --> 00:31:28,360
atomizer, in which
there's oil.

599
00:31:28,360 --> 00:31:33,000
And by the action of atomization
we form a shower

600
00:31:33,000 --> 00:31:36,060
here, a very, very fine
dispersion of

601
00:31:36,060 --> 00:31:37,680
tiny droplets of oil.

602
00:31:37,680 --> 00:31:41,200
And then-- this cartoon is hard
to make sense of so I

603
00:31:41,200 --> 00:31:42,860
fixed this--

604
00:31:42,860 --> 00:31:45,850
we shine high-energy
radiation on this.

605
00:31:45,850 --> 00:31:48,440
And by the action of high energy
radiation we take these

606
00:31:48,440 --> 00:31:51,730
neutral droplets and we
turn them into ions.

607
00:31:51,730 --> 00:31:55,070
We eject electrons.

608
00:31:55,070 --> 00:31:57,340
And so now these are charged.

609
00:31:57,340 --> 00:32:00,730
And then we charge the plates.

610
00:32:00,730 --> 00:32:05,400
So if we have neutral species
and they simply come out of

611
00:32:05,400 --> 00:32:08,020
the atomizer, they'll settle
under gravity.

612
00:32:08,020 --> 00:32:12,090
But now if they're charged and I
put a charge on the plates--

613
00:32:12,090 --> 00:32:14,310
let's say as here the upper
plate is positive--

614
00:32:14,310 --> 00:32:17,385
if any of these particles is
charged positive, the action

615
00:32:17,385 --> 00:32:21,140
of the electric field will
accelerate the descent,

616
00:32:21,140 --> 00:32:23,420
because the bottom plate is
negative attracting and a

617
00:32:23,420 --> 00:32:25,490
positive plate at the
top is repelling.

618
00:32:25,490 --> 00:32:26,630
And vice versa.

619
00:32:26,630 --> 00:32:29,260
If I have a particle that's
negative, the upper positive

620
00:32:29,260 --> 00:32:31,450
plate will actually cause it
to slow down, and in the

621
00:32:31,450 --> 00:32:33,850
extreme, it may actually
start to rise.

622
00:32:33,850 --> 00:32:37,490
And so what Millikan did is a
set of experiments in which he

623
00:32:37,490 --> 00:32:39,880
studied all the different
particle sizes.

624
00:32:39,880 --> 00:32:41,110
See this telescope?

625
00:32:41,110 --> 00:32:43,170
Right over here is Millikan.

626
00:32:43,170 --> 00:32:44,790
And Millikan's sitting
there and he's

627
00:32:44,790 --> 00:32:46,240
squirting and he's watching.

628
00:32:46,240 --> 00:32:48,610
He's measuring the settling
velocity.

629
00:32:48,610 --> 00:32:51,370
And he changes the magnitude
of the electric field.

630
00:32:51,370 --> 00:32:53,590
He changes the intensity
of radiation.

631
00:32:53,590 --> 00:32:55,255
He changes the nozzle.

632
00:32:55,255 --> 00:32:56,960
He changes everything he can.

633
00:32:56,960 --> 00:32:58,090
And what does he find?

634
00:32:58,090 --> 00:33:01,460
He finds that the distribution
of velocities is not

635
00:33:01,460 --> 00:33:03,200
continuous.

636
00:33:03,200 --> 00:33:04,750
It's not continuous.

637
00:33:04,750 --> 00:33:07,580
You think, well, gee if you just
keep dialing you should

638
00:33:07,580 --> 00:33:10,020
get every variation
of velocity.

639
00:33:10,020 --> 00:33:11,060
Well, he doesn't.

640
00:33:11,060 --> 00:33:17,690
He finds that he gets variation
down to a single

641
00:33:17,690 --> 00:33:20,700
value, below which
he can't go.

642
00:33:20,700 --> 00:33:32,440
He determines that electric
charge is quantized.

643
00:33:32,440 --> 00:33:35,080
That is to say there's
a base unit.

644
00:33:35,080 --> 00:33:36,310
It's an element.

645
00:33:36,310 --> 00:33:39,910
I just talked to you about the
elemental building block.

646
00:33:39,910 --> 00:33:42,470
That's an element
in mass space.

647
00:33:42,470 --> 00:33:43,170
Now I'm going to go

648
00:33:43,170 --> 00:33:45,790
conceptually into charge space.

649
00:33:45,790 --> 00:33:49,655
There is an elemental building
block of electric charge.

650
00:33:52,280 --> 00:33:53,840
Electric charge is quantized.

651
00:33:57,950 --> 00:34:06,450
And he found that the elementary
charge, which we

652
00:34:06,450 --> 00:34:08,270
gave the symbol, e.

653
00:34:08,270 --> 00:34:10,430
e is not the symbol
for electron.

654
00:34:10,430 --> 00:34:12,580
e is the symbol for
elementary charge.

655
00:34:12,580 --> 00:34:18,030
It has a value, if you convert
it to modern SI units, of 1.6

656
00:34:18,030 --> 00:34:24,385
times 10 to the minus
19 Coulombs.

657
00:34:24,385 --> 00:34:28,960
So now I can take these two
pieces of information, Faraday

658
00:34:28,960 --> 00:34:31,210
which is up here.

659
00:34:31,210 --> 00:34:34,190
This is known as the
Faraday Constant.

660
00:34:34,190 --> 00:34:38,810
Script f, Faraday constant.

661
00:34:38,810 --> 00:34:41,440
So if I divide the Faraday
constant, which is the charge

662
00:34:41,440 --> 00:34:44,470
on a mole of electrons, by the
elementary charge, which is

663
00:34:44,470 --> 00:34:48,010
the charge on one electron,
presumably I should end up

664
00:34:48,010 --> 00:34:49,350
with the Avogadro number.

665
00:34:49,350 --> 00:34:52,890
It should be the ratio
of the Faraday to

666
00:34:52,890 --> 00:34:54,110
the elementary charge.

667
00:34:54,110 --> 00:34:55,570
And it gives us--

668
00:34:55,570 --> 00:34:56,890
for the third time
this morning--

669
00:34:56,890 --> 00:35:00,190
6.02 times 10 to the 23rd.

670
00:35:00,190 --> 00:35:06,590
If you like per mole, yes
or no, doesn't matter.

671
00:35:06,590 --> 00:35:09,050
So now, what's the
atomic mass unit?

672
00:35:09,050 --> 00:35:13,650
Now we can say the atomic mass
unit is, 1 atomic mass unit

673
00:35:13,650 --> 00:35:15,370
then must equal what?

674
00:35:15,370 --> 00:35:22,590
It's going to equal 1/12 of
the mass of carbon 12.

675
00:35:22,590 --> 00:35:27,420
1/12 of the mass of carbon 12
divided by the Avogadro

676
00:35:27,420 --> 00:35:34,900
number, which gives us 1.661
times 10 to the minus 27

677
00:35:34,900 --> 00:35:36,320
kilograms.

678
00:35:36,320 --> 00:35:39,500
Now be careful because
the system is just

679
00:35:39,500 --> 00:35:40,450
a little bit rickety.

680
00:35:40,450 --> 00:35:44,590
You know we went SI, but look,
this is still defined as 12

681
00:35:44,590 --> 00:35:49,900
grams. And so sometimes if you
look depending on where this

682
00:35:49,900 --> 00:35:54,510
is, 10 to minus 27 kilograms or
10 to the minus 24 grams.

683
00:35:54,510 --> 00:35:55,760
Just be careful.

684
00:35:58,260 --> 00:36:05,040
If you ignore this you'll be off
only by factor of 1,000.

685
00:36:05,040 --> 00:36:05,730
That's a joke.

686
00:36:05,730 --> 00:36:08,250
But it's lost here.

687
00:36:08,250 --> 00:36:09,410
People are too serious.

688
00:36:09,410 --> 00:36:10,660
We'll lighten you up.

689
00:36:10,660 --> 00:36:13,420
All right, so enough
of the history.

690
00:36:13,420 --> 00:36:15,100
Let's now do something
dynamic.

691
00:36:15,100 --> 00:36:16,930
So far we've been studying
static elements.

692
00:36:16,930 --> 00:36:21,010
But chemistry is really the
action of elements in motion.

693
00:36:21,010 --> 00:36:24,060
So how do we describe
a chemical reaction?

694
00:36:24,060 --> 00:36:25,080
Let's look at that.

695
00:36:25,080 --> 00:36:29,090
What are the rules to describe
a chemical reaction?

696
00:36:29,090 --> 00:36:31,190
Write an equation.

697
00:36:31,190 --> 00:36:36,179
Write the equation of the
chemical reaction subject to

698
00:36:36,179 --> 00:36:38,167
these rules.

699
00:36:38,167 --> 00:36:40,652
There are two simple rules.

700
00:36:40,652 --> 00:36:45,544
One is conservation of mass.

701
00:36:45,544 --> 00:36:45,712
We've been told the repeatedly
since Democritus,

702
00:36:45,712 --> 00:36:47,740
conservation of mass.

703
00:36:47,740 --> 00:36:51,440
And the second thing, we use
Dalton's Law of Molar

704
00:36:51,440 --> 00:36:52,690
Proportions.

705
00:36:58,120 --> 00:37:02,750
That is to say, the building
blocks in integer ratios.

706
00:37:06,380 --> 00:37:08,950
And so I thought I'd
do this in context.

707
00:37:08,950 --> 00:37:11,710
So I've got a specific
example here.

708
00:37:11,710 --> 00:37:13,940
So this is something that
I'm interested in.

709
00:37:13,940 --> 00:37:17,810
Some of my research is in
metallurgical extraction by

710
00:37:17,810 --> 00:37:18,910
benign processes.

711
00:37:18,910 --> 00:37:21,400
What you're looking at is
a billet of titanium.

712
00:37:21,400 --> 00:37:23,470
To give you a sense, you can see
the stairwell back here.

713
00:37:23,470 --> 00:37:26,770
So this is about 4 feet, a
little over a meter here.

714
00:37:26,770 --> 00:37:29,720
So you can see this is one
honking big piece of titanium.

715
00:37:29,720 --> 00:37:32,890
This came out of the primary
reactor, the Kroll reactor and

716
00:37:32,890 --> 00:37:36,910
this is subsequently swaged and
hot worked and so on to

717
00:37:36,910 --> 00:37:37,760
form these billets.

718
00:37:37,760 --> 00:37:41,920
So this is the first step of
turning dirt into metal.

719
00:37:41,920 --> 00:37:43,285
That's called titanium sponge.

720
00:37:43,285 --> 00:37:48,550
And titanium sponge occurs
inside a Kroll reactor.

721
00:37:48,550 --> 00:37:51,780
It occurs inside a Kroll
reactor, which was invented by

722
00:37:51,780 --> 00:37:56,440
a man of the surname Kroll in
Luxembourg in the 1930s.

723
00:37:56,440 --> 00:37:59,870
And then with the advent of
World War II, he decided to be

724
00:37:59,870 --> 00:38:01,120
smart, to get out.

725
00:38:01,120 --> 00:38:04,190
And he ended up in Oregon where
he became a professor.

726
00:38:04,190 --> 00:38:06,580
So he's known as Professor
Kroll, although the truth be

727
00:38:06,580 --> 00:38:08,560
told he really made
his discovery

728
00:38:08,560 --> 00:38:09,820
before he became a professor.

729
00:38:09,820 --> 00:38:12,380
But he's still a professor
and so we'll honor him.

730
00:38:12,380 --> 00:38:19,970
And so the Kroll process for
making titanium centers around

731
00:38:19,970 --> 00:38:21,200
this reaction.

732
00:38:21,200 --> 00:38:27,280
Here's the reaction written
according to the rules above.

733
00:38:27,280 --> 00:38:30,460
We take titanium dioxide, which
is found in the Earth

734
00:38:30,460 --> 00:38:33,910
and by some prior chemistry
convert it to titanium

735
00:38:33,910 --> 00:38:37,200
tetrachloride, and in a reactor
that I'm going to show

736
00:38:37,200 --> 00:38:39,190
you in a moment, we
react titanium

737
00:38:39,190 --> 00:38:41,150
tetrachloride with magnesium.

738
00:38:41,150 --> 00:38:44,040
And magnesium has a higher
affinity for chlorine than

739
00:38:44,040 --> 00:38:48,660
does titanium and steals the
chlorine from titanium to form

740
00:38:48,660 --> 00:38:53,130
magnesium chloride, leaving
behind titanium metal.

741
00:38:53,130 --> 00:38:55,760
Now we have to have conservation
of mass.

742
00:38:55,760 --> 00:38:58,860
So you can see, I've got 4
chlorines on the left but only

743
00:38:58,860 --> 00:39:00,130
2 chlorines on the right.

744
00:39:00,130 --> 00:39:02,930
So I'm going to put a
2 here and double

745
00:39:02,930 --> 00:39:04,140
the magnesium chloride.

746
00:39:04,140 --> 00:39:06,070
But now I've got 2 magnesiums
on the right and

747
00:39:06,070 --> 00:39:07,330
only 1 on the left.

748
00:39:07,330 --> 00:39:09,920
So I'll put a 2 in front of the
magnesium and now we have

749
00:39:09,920 --> 00:39:11,170
a balanced equation.

750
00:39:14,100 --> 00:39:17,580
And here's what the reactor
looks like.

751
00:39:17,580 --> 00:39:21,370
You can imagine a giant vessel
with a pressure seal on the

752
00:39:21,370 --> 00:39:24,660
top and a couple of valves,
big enough to make this.

753
00:39:24,660 --> 00:39:27,900
So this is about 15
feet by 30 feet.

754
00:39:27,900 --> 00:39:32,210
And so we introduce titanium
tetrachloride, which is a gas,

755
00:39:32,210 --> 00:39:36,760
and magnesium as a solid and
heat to 900 degrees C.

756
00:39:36,760 --> 00:39:39,310
And at 900 degrees C, if you
look on your Periodic Table

757
00:39:39,310 --> 00:39:42,450
you'll know that magnesium
melts at 650 degrees C.

758
00:39:42,450 --> 00:39:45,250
So we have a liquid sitting
here, titanium tetrachloride

759
00:39:45,250 --> 00:39:47,830
here, and this thing
is sealed.

760
00:39:47,830 --> 00:39:49,550
It's called a bomb reactor.

761
00:39:49,550 --> 00:39:51,190
Nothing can get in, nothing
can get out.

762
00:39:51,190 --> 00:39:52,630
The pressure builds up here.

763
00:39:52,630 --> 00:39:55,100
And right at this interface
the titanium tetrachloride

764
00:39:55,100 --> 00:39:57,840
reacts with the magnesium
according to this reaction.

765
00:39:57,840 --> 00:39:59,280
Now this is very interesting.

766
00:39:59,280 --> 00:40:01,530
It's beautiful reaction
because the titanium

767
00:40:01,530 --> 00:40:04,880
tetrachloride is a gas;
magnesium is a liquid.

768
00:40:04,880 --> 00:40:07,740
Magnesium chloride is a liquid,
but it is of different

769
00:40:07,740 --> 00:40:11,300
density, and it is insoluble
in magnesium, and titanium

770
00:40:11,300 --> 00:40:13,620
melts at 1670 and
it's a solid.

771
00:40:13,620 --> 00:40:16,260
So what happens over
time is this.

772
00:40:16,260 --> 00:40:19,920
The magnesium chloride that
forms pools underneath the

773
00:40:19,920 --> 00:40:22,790
magnesium liquid, gets out
of the way so that we can

774
00:40:22,790 --> 00:40:25,750
continue to keep this interface
clean and have the

775
00:40:25,750 --> 00:40:26,970
reaction proceed.

776
00:40:26,970 --> 00:40:31,630
You don't want to reaction where
reactant A reacts with

777
00:40:31,630 --> 00:40:34,710
reactant B, makes a product that
covers the interface and

778
00:40:34,710 --> 00:40:38,000
now the product is in the
way of future reaction.

779
00:40:38,000 --> 00:40:40,760
So this is very elegant because
I don't need any fans,

780
00:40:40,760 --> 00:40:43,420
I don't need any nose
propellers, nothing.

781
00:40:43,420 --> 00:40:46,110
By density the magnesium
chloride settles and the

782
00:40:46,110 --> 00:40:47,370
titanium settles.

783
00:40:47,370 --> 00:40:48,740
And it's sitting here
at the bottom.

784
00:40:48,740 --> 00:40:51,010
And you can imagine if we do
this long enough, this

785
00:40:51,010 --> 00:40:54,120
titanium at the bottom will
continue to build until it

786
00:40:54,120 --> 00:40:56,190
looks like this.

787
00:40:56,190 --> 00:40:59,342
As long as you keep feeding
TiCl and Mg.

788
00:40:59,342 --> 00:41:01,160
See I'm talking metallurgy
now.

789
00:41:01,160 --> 00:41:04,980
TiCl and Mg, that's
what you make.

790
00:41:04,980 --> 00:41:08,350
So that's how we make titanium,
first step.

791
00:41:08,350 --> 00:41:12,120
And so suppose you get hired and
it's your first day on the

792
00:41:12,120 --> 00:41:19,500
job and you're working at
Cambridge Titanium and the

793
00:41:19,500 --> 00:41:29,160
boss says let's put in 200
kilograms of TiCl and we'll

794
00:41:29,160 --> 00:41:34,060
put in 25 kilograms of Mg.

795
00:41:34,060 --> 00:41:38,590
And the question is,
what is the yield?

796
00:41:38,590 --> 00:41:39,670
What is the yield?

797
00:41:39,670 --> 00:41:42,590
How much titanium are
we going to make?

798
00:41:42,590 --> 00:41:44,240
Well, you say, just
multiply it out.

799
00:41:44,240 --> 00:41:47,940
But first you have to see if
things are in balance.

800
00:41:47,940 --> 00:41:52,410
We have to study the
stoichiometry of the reaction.

801
00:41:52,410 --> 00:41:54,260
Stoichiometry, what
does this mean?

802
00:41:54,260 --> 00:41:56,590
It's from the Greek, stoicheia,
which has to do

803
00:41:56,590 --> 00:41:59,300
with measurement proportions.

804
00:41:59,300 --> 00:42:04,740
So if these are not put in to
the reactor in proportion to

805
00:42:04,740 --> 00:42:07,360
what they are in the equation
we're not going to get the

806
00:42:07,360 --> 00:42:08,870
yield here.

807
00:42:08,870 --> 00:42:12,250
So first thing I gotta do, this
is in moles, this is in

808
00:42:12,250 --> 00:42:15,700
kilograms. So I have to convert
the kilograms to moles

809
00:42:15,700 --> 00:42:17,660
and then maybe I can make
some sense of this.

810
00:42:17,660 --> 00:42:21,255
So if I divide by the atomic
mass of titanium, four times

811
00:42:21,255 --> 00:42:24,910
the atomic mass of chlorine and
convert; I will discover

812
00:42:24,910 --> 00:42:30,770
that I have 1,054
moles of TiCl.

813
00:42:30,770 --> 00:42:36,770
And I've got about 1,029
moles of magnesium.

814
00:42:36,770 --> 00:42:43,170
Well, this equation says I need
2 times the amount of

815
00:42:43,170 --> 00:42:44,160
titanium tetrachloride.

816
00:42:44,160 --> 00:42:47,180
Well, it's obvious to the naked
eye, 1,029 isn't two

817
00:42:47,180 --> 00:42:49,150
times 1,054.

818
00:42:49,150 --> 00:42:50,690
So I've got a problem here.

819
00:42:50,690 --> 00:42:54,290
I'm not going to get as much
titanium as I put in.

820
00:42:54,290 --> 00:42:55,540
Titanium chloride.

821
00:42:55,540 --> 00:42:57,930
This yield is going
to be restricted.

822
00:42:57,930 --> 00:43:00,510
It's going to be restricted by--
this is sort of a chain

823
00:43:00,510 --> 00:43:02,420
is as strong as its
weakest link--

824
00:43:02,420 --> 00:43:06,910
the yield is restricted by the
amount of limiting reagent.

825
00:43:06,910 --> 00:43:11,820
And in this case, magnesium is--
this is less than 2 times

826
00:43:11,820 --> 00:43:15,630
the mole number of titanium
chloride.

827
00:43:15,630 --> 00:43:17,950
So this means this is the
limiting reagent.

828
00:43:22,510 --> 00:43:26,470
Alright so now if we use that
principle then I'm only going

829
00:43:26,470 --> 00:43:28,910
to get as much titanium as I had
magnesium and you can see

830
00:43:28,910 --> 00:43:32,140
from the stoichiometry here,
if I've got 1,029 moles of

831
00:43:32,140 --> 00:43:33,800
magnesium I'm going
to have half of

832
00:43:33,800 --> 00:43:35,510
that number of titanium.

833
00:43:35,510 --> 00:43:42,430
So therefore the amount of
titanium is equal to 515 moles

834
00:43:42,430 --> 00:43:43,410
of titanium.

835
00:43:43,410 --> 00:43:46,730
And you notice I'm not obsessed
about a significant

836
00:43:46,730 --> 00:43:47,600
figures and so on.

837
00:43:47,600 --> 00:43:49,980
It's a metallurgical plant.

838
00:43:49,980 --> 00:43:51,990
Half of 1,029 is 515.

839
00:43:51,990 --> 00:43:53,900
Is it 514.5?

840
00:43:53,900 --> 00:43:54,590
If you wish.

841
00:43:54,590 --> 00:43:55,060
I don't care.

842
00:43:55,060 --> 00:43:59,330
So 515 moles and then I convert
that, which gives me

843
00:43:59,330 --> 00:44:05,430
24.7 kilograms of titanium
when I use

844
00:44:05,430 --> 00:44:07,240
that amount of magnesium.

845
00:44:07,240 --> 00:44:11,720
And if you go to the text,
Section 2.7, you'll see the

846
00:44:11,720 --> 00:44:14,580
nuts and bolts of how to
run these reactions.

847
00:44:14,580 --> 00:44:16,355
For those of you who had a lot
of chemistry in high school, I

848
00:44:16,355 --> 00:44:18,900
know this is review, but I want
to bring everybody up to

849
00:44:18,900 --> 00:44:20,600
the same page.

850
00:44:20,600 --> 00:44:23,530
So we're starting with this.

851
00:44:23,530 --> 00:44:24,070
All right.

852
00:44:24,070 --> 00:44:26,940
I think that's a pretty
good place to

853
00:44:26,940 --> 00:44:28,930
stop with the delivery.

854
00:44:28,930 --> 00:44:31,130
But I don't want you moving.

855
00:44:31,130 --> 00:44:31,690
You don't move yet.

856
00:44:31,690 --> 00:44:33,080
Because the last 5 minutes
I'm going to

857
00:44:33,080 --> 00:44:34,150
still continue to talk.

858
00:44:34,150 --> 00:44:36,040
But on a slightly
different topic.

859
00:44:36,040 --> 00:44:38,320
And so I don't want to
hear the binders

860
00:44:38,320 --> 00:44:41,020
snapping and so on.

861
00:44:41,020 --> 00:44:42,590
We're here; you paid
your money.

862
00:44:42,590 --> 00:44:44,150
Five more minutes.

863
00:44:44,150 --> 00:44:46,090
Five more minutes and then
you're out there.

864
00:44:46,090 --> 00:44:48,200
Out there, then begins
le weekend.

865
00:44:48,200 --> 00:44:49,820
But not until then.

866
00:44:49,820 --> 00:44:51,260
So a couple of things.

867
00:44:51,260 --> 00:44:52,960
First is, the music today.

868
00:44:52,960 --> 00:44:54,760
I try to link the music
thematically.

869
00:44:54,760 --> 00:45:01,260
So the music playing today was
Polovstian Dance number 17

870
00:45:01,260 --> 00:45:05,510
from Prince Igor, by Borodin,
Aleksandr Borodin.

871
00:45:05,510 --> 00:45:07,210
Why were we listening
to this music?

872
00:45:07,210 --> 00:45:09,870
Well, because I insisted
that we listen to it.

873
00:45:09,870 --> 00:45:11,060
Well, what about Borodin?

874
00:45:11,060 --> 00:45:13,270
Borodin lived in Saint
Petersburg.

875
00:45:13,270 --> 00:45:14,860
He was a friend of Mendeleyev.

876
00:45:14,860 --> 00:45:19,100
OK, that's cute but more
importantly Borodin wrote his

877
00:45:19,100 --> 00:45:20,930
music in his leisure time.

878
00:45:20,930 --> 00:45:22,050
He had a day job.

879
00:45:22,050 --> 00:45:25,690
His day job was professor
of chemistry.

880
00:45:25,690 --> 00:45:28,570
And he worked at the Medical
Surgical Academy in Saint

881
00:45:28,570 --> 00:45:29,630
Petersburg.

882
00:45:29,630 --> 00:45:31,920
He was an exceptional
human being.

883
00:45:31,920 --> 00:45:34,980
In those days, women were
forbidden to attend

884
00:45:34,980 --> 00:45:36,830
institutions of higher
education.

885
00:45:36,830 --> 00:45:42,190
He set up an entire curriculum
for women in a night school at

886
00:45:42,190 --> 00:45:44,710
the Medical Surgical Academy.

887
00:45:44,710 --> 00:45:47,560
He cavorted with artists and
therefore obviously his

888
00:45:47,560 --> 00:45:48,810
politics were radical.

889
00:45:48,810 --> 00:45:51,890
And they were trying to reform
the political scene in Czarist

890
00:45:51,890 --> 00:45:53,440
Russia at the time.

891
00:45:53,440 --> 00:45:56,700
And he was also quite
a bon vivant.

892
00:45:56,700 --> 00:46:03,080
And he died on his feet
dancing at a ball.

893
00:46:03,080 --> 00:46:04,570
So that's the way to go.

894
00:46:04,570 --> 00:46:06,200
Having a great time.

895
00:46:06,200 --> 00:46:07,450
That was Borodin.

896
00:46:09,590 --> 00:46:11,160
One other thing before you go.

897
00:46:11,160 --> 00:46:14,680
You were very very dour, so I
thought I'd try to put you in

898
00:46:14,680 --> 00:46:17,800
a good mood to the extent this
is possible with this group.

899
00:46:17,800 --> 00:46:22,050
And I wanted to share
with you some news.

900
00:46:22,050 --> 00:46:23,780
There's been a new element
discovered.

901
00:46:23,780 --> 00:46:26,640
You know these atoms smashers,
they're always working.

902
00:46:26,640 --> 00:46:29,340
And so the discovery of the
heaviest element known to

903
00:46:29,340 --> 00:46:31,170
science has been reported.

904
00:46:31,170 --> 00:46:33,750
The element, tentatively
named administratium.

905
00:46:36,900 --> 00:46:39,530
I don't know if UPEC is going
to go for this, but you can

906
00:46:39,530 --> 00:46:41,910
suggest names.

907
00:46:41,910 --> 00:46:44,430
So they're going to name
is administratium, the

908
00:46:44,430 --> 00:46:47,240
discoverers.

909
00:46:47,240 --> 00:46:50,830
It has no protons
or electrons.

910
00:46:50,830 --> 00:46:55,500
So that means its atomic
number is 0.

911
00:46:55,500 --> 00:47:00,850
It does have one neutron, 125
assistants to the neutron.

912
00:47:00,850 --> 00:47:04,820
75 vice-neutrons and a
111 assistants to the

913
00:47:04,820 --> 00:47:06,360
vice-neutrons.

914
00:47:06,360 --> 00:47:11,580
This gives it a mass
number of 312.

915
00:47:11,580 --> 00:47:14,660
The 312 particles are held
together in the nucleus by a

916
00:47:14,660 --> 00:47:17,210
force that involves the
continuous exchange of

917
00:47:17,210 --> 00:47:21,430
meson-like particles
called memo-ons.

918
00:47:21,430 --> 00:47:24,470
There's no electronic mail,
because there's no electrons.

919
00:47:24,470 --> 00:47:27,220
There may be neutronic mail
but we don't know yet.

920
00:47:27,220 --> 00:47:29,110
Now you've already learned
something today.

921
00:47:29,110 --> 00:47:30,220
You know something.

922
00:47:30,220 --> 00:47:32,640
Since it has no electrons,
what do we know about its

923
00:47:32,640 --> 00:47:34,820
chemical reactivity?

924
00:47:34,820 --> 00:47:35,805
It's inert.

925
00:47:35,805 --> 00:47:37,080
It has no electrons.

926
00:47:37,080 --> 00:47:38,230
It can't exchange.

927
00:47:38,230 --> 00:47:39,450
So this is chemically inert.

928
00:47:39,450 --> 00:47:42,920
So you say, how did
they detect it?

929
00:47:42,920 --> 00:47:44,940
Because it seems to impede
every reaction in

930
00:47:44,940 --> 00:47:46,190
which it is a present.

931
00:47:49,290 --> 00:47:53,010
According to the discoverers
a few nanograms rendered a

932
00:47:53,010 --> 00:47:58,420
reaction that normally takes a
fraction of a second, it took

933
00:47:58,420 --> 00:48:01,635
now four business days
to conduct that same.

934
00:48:04,450 --> 00:48:07,370
There are a few other
properties.

935
00:48:07,370 --> 00:48:10,030
We know so far that
it's radioactive.

936
00:48:10,030 --> 00:48:11,990
And we're going to study
radioactivity later, so

937
00:48:11,990 --> 00:48:13,830
there's a little bit
of foreshadowing.

938
00:48:13,830 --> 00:48:16,850
It has a half-life of about
three years, at which time it

939
00:48:16,850 --> 00:48:22,240
stops decaying and instead it
undergoes a reorganization, in

940
00:48:22,240 --> 00:48:24,780
which the vice-neutrons,
assistants to the neutrons and

941
00:48:24,780 --> 00:48:25,310
assistants to the

942
00:48:25,310 --> 00:48:27,810
vice-neutrons, exchange places.

943
00:48:27,810 --> 00:48:32,040
Some studies indicate that the
mass actually increases after

944
00:48:32,040 --> 00:48:33,760
each reorganization.

945
00:48:33,760 --> 00:48:36,970
So you can imagine now we'll
have something like this.

946
00:48:40,590 --> 00:48:43,270
See how this increased?

947
00:48:43,270 --> 00:48:47,370
So if they occupy the same
place, they have the same

948
00:48:47,370 --> 00:48:51,110
proton number, but a different
neutron number, in the case of

949
00:48:51,110 --> 00:48:55,080
administratium, they're
called isodopes.

950
00:48:55,080 --> 00:48:57,820
So with that I will say,
have a good weekend.