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History of the Periodic Table of the Elements
(CHEM 1360)Part 3
Lavoisier’s Elements
“Elements in the body”
“Earths”
“Nonmetallic elements”
“Metallic elements”
John DaltonManchester, England
1810
“Atoms are featurelessspheres. The only
difference betweendifferent elements
is their weight.For example:
Hydrogen 1Carbon 5Oxygen 7
Phosphorus 9Sulphur 13
Magnesia 20Lime 24
Potash 42 Iron 50Lead 90
Mercury 167Gold 190”
These are models of atoms constructed by Dalton,
now on display in a Manchester museum.
Jöns Jacob BerzeliusStockholm, Sweden
1826
DeterminedAtomic
Weights Accurately
H 1 Li 7 Be 9.4 B 11 C 12 N 14 O 16 F 19 Na 23 Mg 24 Al 27.3 Si 28 P 31 S 32 Cl 35.5 K 39 Ca 40 Ti 48 V 51 Cr 52 Mn 55 Fe 56 Co 59 Ni 59 Cu 63 Zn 65 As 75 Se 78 Br 80 Rb 85 Sr 87 Y 88 Zr 90 Nb 94 Mo 96 Ru 104 Rh 104 Pd 106 Ag 108 Cd 112 In 113 Sn 118 Sb 122 Te 125 I 127 Cs 133 Ba 137Di 138 Ce 140 Er 178 La 180Ta 182 W 184 Os 195 Ir 197Pt 198 Au 199 Hg 200 Tl 204Pb 207 Bi 208 Th 231 U 240
Atomic Weights (Berzelius*)
*Recalculated using Cannizzaro’s principle
Ca = 40 Sr = 87 Ba = 137
(40+137)/2 = 88.5
Cl = 35.5 Br = 80 I = 127
(35.5+127)/2 = 81.2
K = 39 Rb = 85 Cs = 133
(39+133)/2 = 86
S = 32 Se = 78 Te = 125
(32+125)/2 = 78.5
P = 31 As = 75 Sb = 122
(31+122)/2 = 76.5
“Triads” suggest an underlying pattern
Johann DöbereinerJena, Germany
1829
The Chemical Congress of 1860
The time had come for chemists to resolve several questions and to come to agreement on several conventions.
While Lincoln was debating key issues during thePresidential campaign in the fall of 1860, chemistsfrom all over the world congregated in Karlsruhe.
Ständehaus, Karlsruhe, Germany
Chemical formula symbols were particularly confusing; various conventions were in use, utilizing bars, dots, sometimes
equivalents and sometimes weights. H2O2 could represent either water or hydrogen peroxide, C2H4 either ethylene or methane!
The Chemical Congress debatedseveral key issues. Foremost were(1) the question of whether to usechemical equivalents (the amountof an element that reacts with astandard weight of oxygen) or atomic weights to describe chemical reactions, and (2) what symbolism to use for chemical formulas.
Cannizzaro provides the solution
Stanislao Cannizzaro wrote a famous pamphlet which wasdistributed at the Chemical Congress which clearly distinguished
between atoms and molecules and allowed an unequivocalworking definition of atomic weight. Almost immediately
everyone was converted to his system, which we use today.Cannizzaro based his suggestions on Avogadro’s hypothesis.
Avogadro’s hypothesis is “rediscovered”
Amedeo Avogadro was far ahead of his time when he publishedin 1811 his hypothesis that equal volumes of all gases contain equal
numbers of molecules (at the same temperature and pressure). Cannizzaro showed that application of Avogadro’s hypothesis
produced a self-consistent set of atomic weights.
Cannizzaro “rediscovered”Avogadro’s work on gasvolumes which had been
ignored for half a century.
A word more about volumes of gases. . .
Gay-Lussac had found in 1808 that when gaseschemically react, the volumes of both the reactantsand the products are in simple ratios. For example,
1 volume nitrogen + 3 volumes hydrogenreact to give 2 volumes of ammonia.
Avogadro interpreted this reaction as expressing what happens on an atomic (and molecular) scale,
by borrowing from Dalton’s atomic theory:
N H H H+ Am Am
And a final word about water. . .
Avogadro in 1811 actually hypothesized thecorrect interpretation in the reaction ofhydrogen with oxygen to produce water.
Again, Avogadro explained this reaction as expressing what happens on an atomic (and
molecular) scale, using Dalton’s atomic theory:
O H H+ Wa Wa
Another kind of information which helpedCannizzaro was Dulong-Petit’s law, which wasuseful for solids. It stated that the gram atomic heat capacity is constant. That is, the specificheat (heat required to warm a substance by one degree) is inversely to the atomic weight.
sp. heat at. wt. sp. ht. x at. wt. (O=1)Bi 0.0288 13.30 0.3830Pb 0.0293 12.95 0.3794Au 0.0298 12.43 0.3704 Pt 0.0314 11.16 0.3740Sn 0.0514 7.35 0.3779Ag 0.0557 6.75 0.3759Zn 0.0927 4.03 0.3736
sp. heat at. wt. sp. ht. x at. wt. (O=1)Te 0.0912 4.03 0.3675Cu 0.0949 3.957 0.3755Ni 0.1035 3.69 0.3819Fe 0.1100 3.392 0.3731Co 0.1498 2.46 0.3685S 0.1880 2.011 0.3780
The Cannizzaro Principle
The atomic weight of an element is the least weight of it contained in a (volatile) molecule.
Hydrogen, the lightest gas, is chosen as the standard,and the atomic weight of hydrogen is set at 1.
Since the molecule of hydrogen weighs twice as much as theleast amount in various compounds (e.g., HCl), then the
molecule of hydrogen contains two atoms, and its chemical formula may be set as H2. Since two volumes of hydrogenreact with one volume of oxygen to give two volumes of
water, then it may be unequivocally concluded that
2H2 + O2 2H2O
“I well remember how great was the difference of opinion, and how a compromise was advocated
with great acumen by many scientific men. . . .In the spirit of freedom. . . A compromise was
not arrived at, nor ought it to have been, but instead the truth. . . [which] soon afterwards
convinced all minds.” — Dmitri Mendeleev
“. . . The scales fell from my eyes, doubts vanished, and a feeling of calm certainty
came in their place.” — Lothar Meyer
The two future discoverers of the Periodic Table, after readingCannizzaro’s Pamphlet at the Chemical Congress, stated:
The Discovery of the Modern Periodic Table
Lothar Meyer Dimitri Mendeleev
Two scientists independently discovered the “modern” Periodic Table in 1869.
Mendeleév on his desk played and arranged pieces of paper, listing elements with their respective atomic weights,
trying to find some order.
Dimitri Mendeleév St. Petersburg,
Russia
Mendeleev’s First Table — March, 1869 Ti 50 Zr 90 ?100 V 51 Nb 94 Ta 182 Cr 52 Mo 96 W 186 Mn 55 Rh 104.4 Pt 197.4 Fe 56 Ru 104.4 Ir 198 Ni=Co 59 Pd 106.6 Os 199H 1 Cu 63.4 Ag 108 Hg 200 Be 9.4 Mg 24 Zn 65.2 Cd 112 B 11 Al 27.4 ? 68 U 116 Au 197? C 12 Si 28 ? 70 Sn 118 N 14 P 31 As 75 Sb 122 Bi 210? O 16 S 32 Se 79.4 Te 128? F 19 Cl 35.5 Br 80 I 127Li 7 Na 23 K 39 Rb 85.4 Cs 133 Tl 204 Ca 40 Sr 87.6 Ba 137 Pb 207 ? 45 Ce 92 Er? 56 La 94 Yt? 60 Di 95
In 75.6? Th 118?
1. When arranged by atomic weight, the elements show aperiodicity of properties.2. Similar elements have atomic weights which are either verysimilar (platinum, iridium, osmium) or which increase regularly(potassium, rubidium, cesium).3. The arrangement of the elements correspond to their valences.4. Elements which are most common have small atomic weights.5. The atomic weight can determine the character of an element.6. More elements will be discovered.7. The atomic weight of an element may be corrected bycomparison with adjacent elements.8. Some properties of unknown elements can be predicted fromtheir atomic weights.
Mendeleev made 8 statements about hisTable in his first publication
Lothar Meyer’s Table — December, 1869
I II III IV V VI VII VIII IX B 11 Al 27.3 — — ? In 113.4 Tl 202.7 C 11.97 Si 28 — Sn 117.8 — Pb 206.4 Ti 48 Zr 89.7 N 14.01 P 30.9 As 74.9 Sb 122.1 Bi 207.5 V 51.2 Nb 93.7 Ta 182.2 O 15.96 S 31.98 Se 78.0 Te 128? Cr 52.4 Mo 95.6 W 183.5 F 19.1 Cl 35.38 Br 79.75 I 126.5 Mn 54.8 Ru 103.5 Os 198.6? Fe 55.9 Rh 104.1 Ir 196.7 Co&Ni 58.6 Pd 106.2 Pt 196.7Li 7.01 Na 22.99 K 39.04 Rb 85.2 Cs 132.7 Cu 63.3 Ag 107.66 Au 196.2?Be 9.7 Mg 23.9 Ca39.9 Sr 87.0 Ba 136.8 Zn 64.9 Cd 111.6 Hg 199.8
Lothar Meyer’s plot
Atomic weight
Ato
mic
vol
um
e
Lothar Meyer’s plot shows definite spikes in an ascending cyclicpattern that suggests an internal structure. The intriguing
question of atomic structure had to wait for another half century,until spectroscopists and theoreticians could attack the problem.
Differences between Mendeleev and Meyer
1. Mendeleev did not concern himself with why the table worked.He just boldly proclaimed that the trends were real, and thatin fact the properties of unknown elements could be predicted!2. Meyer was not so daring about the predictive power of thetable. He was very curious, however, with the reasons for thetrends, which he thought reflected some internal structure.3. Mendeleev thought the elements were primordial matter.4. Meyer thought there must be yet smaller particles.5. Mendeleev continued to work on his table, which very quickly was successful in predicting specific elements — and he became famous.6. It took scientists many decades understand exactly how Meyer’s plot described an inner structure of the atom, and his work was eclipsed by these scientists who discovered thisstructure of protons, electrons, and neutrons.
PERIODIC TABLE OF THE ELEMENTS(Mendeléeff, 1871)
Row 1R2O
2RO
3R2O3
4RO2
RH4
5R2O5
RH3
6RO3
RH2
7R2O7
RH
8RO4
1 H1
2 Li7
Be9.4
B11
C12
N14
O16
F19
3 Na23
Mg24
Al27.
3)
Si28
P31
S32
Cl35.
5)4 K
39Ca40
"eka-B"44?
Ti48
V51
Cr52
Mn55
Fe56
Co59
Ni59
5 Cu63
Zn65
"eka-Al"68?
"eka-Si"72?
As75
Se78
Br80
6 Rb85
Sr87
Y88
Zr90
Nb94
Mo96 100
?)
Ru104
)
Rh104
)
Pd106
)7 Ag
108)
Cd112
)
In113
)
Sn118
)
Sb122
)
Te125
)
I127
)8 Cs
133)
Ba137
)
Di138
)
Ce140
)9
10 Er178
)
La180
)
Ta182
)
W184
)
Os195
)
Ir197
)
Pt198
)11 Au
199)
Hg200
)
Tl204
)
Pb207
)
Bi208
)12 Th
231)
U240
)Mendeléeff assumed: oxide of Be = BeO oxide of In = In2O3
oxide of U = UO3
? ?
? ?
? ?
?
Predicted!
Misfits?
Correct value?
eka-boron
eka-aluminum
eka-silicon
Mendeleev simply followed the trends of the table to interpolate the properties of three new elements, which he called eka-boron,
eka-aluminum, and eka-silicon. He predicted the atomicweights would be 44, 68, and 72, respectively, and he predictedthe chemical properties and physical properties of each of these
elements.
His paper didn’t get much attention until. . . .
How Mendeleev predicted unknown elements
Eka-B
44
Eka-Al
68
Eka-Si
72
Gallium - discovered 1875
Boisbaudran discovers eka-aluminum
Predicted Found at. wt. = 68 at. wt. = 69.9 sp. gr. = 5.9 sp. gr. = 5.94 low m.p. m.p. = 30º Oxide Ea2O3 Oxide Ga2O3
soluble in acids soluble in acids and bases and bases
Lecoq de Boisbaudran,Cognac, France
Scandium - discovered 1879
Nilson discovers eka-boron
Predicted Found at. wt. = 44 at. wt. = 44 Oxide Eb2O3 Oxide Sc2O3
with sp. gr. = with sp.gr. =3.5, not soluble 3.86, not soluble in alkalies in alkalies
Lars Fredrik Nilson,Uppsala, Sweden
Germanium - discovered 1886
Winkler discovers eka-silicon
Predicted Found at. wt. = 72 at. wt. = 72.3 Oxide EsO2 Oxide GeO2
with sp. gr. = with sp. gr. = 4.7 4.70Volatile chloride GeCl4 with EsCl4 b.p. = 86 º
Clemens Winkler, Freiberg, Germany
PERIODIC TABLE OF THE ELEMENTS(Mendeléeff, 1891)
1 2 3 4 5 6 7 8 1 2 3 4 5 6 7
R2O RO R2O3 RO2 R2O5 RO3 R2O7 R2O RO R2O3 RO2 R2O5 RO3 R2O7
H1
Li7
Be9
B11
C12
N14
O16
F19
Na23
Mg24
Al27
Si28
P31
S32
Cl35.5
)K39
Ca40
Sc44
Ti48
V51
Cr52
Mn55
Fe56
Co58.
5)
Ni59
Cu63
Zn65
Ga70
Ge72
As75
Se79
Br80
Rb85
Sr87
Y89
Zr90
Nb94
Mo96
Ru103
)
Rh104
)
Pd106
)
Ag108
)
Cd112
)
In113
)
Sn118
)
Sb120
)
Te125
)
I127
)Cs133
)
Ba137
)
La138
)
Ce140
)Yb173
)
Ta182
)
W184
)
Os191
)
Ir193
)
Pt196
)
Au198
)
Hg200
)
Tl294
)
Pb206
)
Bi208
)Th232
)
U240
)
Also known in 1891: Er, Tb, Ho, Tm, Sm, Gd, Pr, Nd, DyDifficulties include: Brauner found Te = 127.6 1889
A new family of elements?!
Sir William Ramsey University College
(London)
New gasisolated from
the atmosphere!
PERIODIC TABLE OF THE ELEMENTS(1894)
1 2 3 4 5 6 7 8 1 2 3 4 5 6 7
R2O RO R2O3 RO2 R2O5 RO3 R2O7 R2O RO R2O3 RO2 R2O5 RO3 R2O7
H1
Li7
Be9
B11
C12
N14
O16
F19
Na23
Mg24
Al27
Si28
P31
S32
Cl35.5
)
Ar40
K39
Ca40
Sc45
Ti48
V51
Cr52
Mn55
Fe56
Co59
Ni59
Cu63
Zn65
Ga70
Ge73
As75
Se79
Br80
Rb85
Sr88
Y89
Zr91
Nb93
Mo96
Ru101
Rh104
Pd106
Ag108
Cd112
In115
Sn119
Sb122
Te128
I127
Cs133
Ba137
La139
Ce140
Yb173
Ta181
W184
Os190
Ir192
Pt195
Au197
Hg201
Tl204
Pb207
Bi209
Th232
U238
Also known in 1894: Er, Tb, Ho, Tm, Sm, Gd, Pr, Nd, DyA new column is needed for the new element!
PERIODIC TABLE OF THE ELEMENTS(1895)
1 2 3 4 5 6 7 8 1 2 3 4 5 6 7
R2O RO R2O3 RO2 R2O5 RO3 R2O7 R2O RO R2O3 RO2 R2O5 RO3 R2O7
H1
He4
Li7
Be9
B11
C12
N14
O16
F19
Na23
Mg24
Al27
Si28
P31
S32
Cl35.5
)
Ar40
K39
Ca40
Sc45
Ti48
V51
Cr52
Mn55
Fe56
Co59
Ni59
Cu63
Zn65
Ga70
Ge73
As75
Se79
Br80
Rb85
Sr88
Y89
Zr91
Nb93
Mo96
Ru101
Rh104
Pd106
Ag108
Cd112
In115
Sn119
Sb122
Te128
I127
Cs133
Ba137
La139
Ce140
Yb173
Ta181
W184
Os190
Ir192
Pt195
Au197
Hg201
Tl204
Pb207
Bi209
Th232
U238
Also known in 1895: Er, Tb, Ho, Tm, Sm, Gd, Pr, Nd, DyAnother gas discovered! (was originally seen in the sun)
PERIODIC TABLE OF THE ELEMENTS(1898)
1 2 3 4 5 6 7 8 1 2 3 4 5 6 7
R2O RO R2O3 RO2 R2O5 RO3 R2O7 R2O RO R2O3 RO2 R2O5 RO3 R2O7
H1
He4
Li7
Be9
B11
C12
N14
O16
F19
Na23
Mg24
Al27
Si28
P31
S32
Cl35.5
)
Ar40
K39
Ca40
Sc45
Ti48
V51
Cr52
Mn55
Fe56
Co59
Ni59
Cu63
Zn65
Ga70
Ge73
As75
Se79
Br80
Kr84
Rb85
Sr88
Y89
Zr91
Nb93
Mo96
Ru101
Rh104
Pd106
Ag108
Cd112
In115
Sn119
Sb122
Te128
I127
Xe131
Cs133
Ba137
La139
Ce140
Yb173
Ta181
W184
Os190
Ir192
Pt195
Au197
Hg201
Tl204
Pb207
Bi209
Th232
U238
Also known in 1898: Er, Tb, Ho, Tm, Sm, Gd, Pr, Nd, DyTwo more gases discovered!
PERIODIC TABLE OF THE ELEMENTS(1898)
1 2 3 4 5 6 7 8 1 2 3 4 5 6 7
R2O RO R2O3 RO2 R2O5 RO3 R2O7 R2O RO R2O3 RO2 R2O5 RO3 R2O7
H1
He4
Li7
Be9
B11
C12
N14
O16
F19
Ne20
Na23
Mg24
Al27
Si28
P31
S32
Cl35.5
)
Ar40
K39
Ca40
Sc45
Ti48
V51
Cr52
Mn55
Fe56
Co59
Ni59
Cu63
Zn65
Ga70
Ge73
As75
Se79
Br80
Kr84
Rb85
Sr88
Y89
Zr91
Nb93
Mo96
Ru101
Rh104
Pd106
Ag108
Cd112
In115
Sn119
Sb122
Te128
I127
Xe131
Cs133
Ba137
La139
Ce140
Yb173
Ta181
W184
Os190
Ir192
Pt195
Au197
Hg201
Tl204
Pb207
Bi209
Th232
U238
Also known in 1898: Er, Tb, Ho, Tm, Sm, Gd, Pr, Nd, DyAnother gas discovered ! (Table needs to be restacked)
Mendeléeff's Last Periodic Table(1902)
Row
0R
1R2O
2RO
3R2O3
4RO2
5R2O5
6RO3
7R2O7
8RO4
1 H1.008
2 He4.0
Li7.03
Be9.1
B11.0
C12.0
N14.0
4
O16.0
0
F19.0
3 Ne19.9
Na23.0
5
Mg24.3
Al27.0
Si28.4
P31.0
S32.0
6
Cl35.4
54 Ar
38K
39.1Ca40.1
Sc44.1
Ti48.1
V51.4
Cr52.1
Mn55.0
Fe55.9
Co59
Ni59
5 Cu63.6
Zn65.4
Ga70
Ge72.3
As75
Se79
Br79.9
56 Kr
81.8Rb85.4
Sr87.6
Y89.0
Zr90.6
Nb94.0
Mo96.0
Ru101.7
Rh103.0
Pd106.5
7 Ag107.9
Cd112.4
In114.0
Sn119.0
Sb120.0
Te127
I127
8 Xe128
Cs132.9
Ba137.4
La139
Ce140
9
10 Yb173
Ta183
W184
Os191
Ir193
Pt194.9
11 Au197.2
Hg200.0
Tl204.1
Pb206.9
Bi208
12 Ra224
Th232
U239
Not included: Er, Tb, Ho, Tm, Sm, Gd, Pr, Nd, Dy, Eu, Po, Ac, Rn
PERIODIC TABLE OF THE ELEMENTS(Brauner, 1902)
Row 0R
1R2O
2RO
3R2O3
4RO2
RH4
5R2O5
RH3
6RO3
RH2
7R2O7
RH
8RO4
1 H1
2 He4
Li7
Be9
B11
C12
N14
O16
F19
3 Ne20
Na23
Mg24
Al27
Si28
P31
S32
Cl35.5
4 Ar40
K39
Ca40
Sc44
Ti48
V51
Cr52
Mn55
Fe56
Co59
Ni59
5 Cu63
Zn65
Ga70
Ge72
As75
Se78
Br80
6 Kr82
Rb85
Sr87
Y89
Zr90
Nb94
Mo96 100
Ru102
Rh103
Pd106
7 Ag108
Cd112
In114
Sn119
Sb120
Te128
I127
8 Xe128
Cs133
Ba137
La139
Ce140
Pr141
Nd144 145
147Sm148
Eu151 152
155Gd
156 159 160Tb
163Ho
165Er
166 167Tm171
Yb173 176
178Ta
182W
184 190Os
191Ir
193Pt
1959 Au
197Hg
200Tl
204Pb
207Bi
209 212 21410
218 220Ra
225 230Th
233 235U
239
Not included: Dy, Po, Ac, Rn
Predicted?!
Bauner predicted 98
elements through uranium
Brauner attempted to find order in
the higher elements
Bohuslav Brauner Prague, Bohemia
A further complication — Rutherforddiscovers the “transmutation” of elements
In 1902-1905 Ernest Rutherford discovered that radium decays through a series of steps, leading apparently to a new group of elements: Ra Rn Ra-A Ra-B Ra-C
Ra-E Ra-F Ra-G
A glut of new elements?!
Rutherford’s finding led to the discoveries by other invesigators of a plethora of new elements in other decay schemes during the first decade of 1900. These elements
included: “ionium,” “brevium,” “actinouranium,” “radiothorium,” “niton,” “actinon,” “thorium-X,”
“uranium-X,” and dozens more.
The confusing feature of all these newly discovered elements was that in many instances some of them had very similar, and perhaps identical, chemical properties
— even though they had different half-lives.
Soddy solves the problem
In 1913 Soddy conceived the idea of an “isotope.” Isotopes (from Greek “isos” meaning “same,” and “topos” meaning “place”) are “in the same place” in the Periodic Table and yet have different nuclear properties. Thus, for example, the “brevium” of Fajans,
the “ekatantalum” of Soddy, and the “protactinium” of Hahn and Meitner all belong in the same slot in the Periodic Table — they
are isotopes of the same element (protactinium).
PERIODIC TABLE OF THE ELEMENTS(1907)
1A 2A 3B 4B 5B 6B 7B 8B 1B 2B 3A 4A 5A 6A 7A 8A
H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba Rare earths Ta W Os Ir Pt Au Hg Tl Pb Bi Po Rn
Ac Th U
Rare earths: La, Ce, Er, Tb, Ho, Tm, Yb, Sm, Gd, Pr, Nd, Dy, Eu, Lu
This was the best guess by 1907 — but it was still not known how many elements actually existed. . . . until. . . . .
1 - N =
43
0ν
νMoseley — 1912
Where N = atomic number of element
v = 1/λ = wavenumber of Kα X-ray line
v0 = Rydberg constant
Henry MoseleyOxford, England
Moseley predicted the following elements were yet to be discovered:
43, 61, 75, 85, 87
From Moseley’s work, scientists now knew that there were exactly 92 elements ranging from
hydrogen to uranium.
And using quantum theory, Bohr was ready to propose the modern form of the Periodic Table. . . .
PERIODIC TABLE OF THE ELEMENTS(1925)
1A 2A 3B 4B 5B 6B 7B 8B 1B 2B 3A 4A 5A 6A 7A 8A
H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba La* Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po Rn
Ra Ac Th Pa U
* Rare earths
Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Bohr explained behavior of transition elements and rare-earth elements in 1922. Hafnium was discovered in zirconium ore after Bohr's suggestion that the missing element would behave more like zirconium than like a rare earth element. Rhenium was discovered from platinum ores. "Masurium" (eka-manganese) was announced but later discredited. "Illinium" (the missing rare earth) was announced but later discredited.
Niels BohrCopenhagen, Denmark
19391940
1937
Only one left to be discovered!
Glenn SeaborgBerkeley, California
PERIODIC TABLE OF THE ELEMENTS(1940)
1A 2A 3B 4B 5B 6B 7B 8B 1B 2B 3A 4A 5A 6A 7A 8A
H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba La* Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Fr Ra Ac*** Lanthanides
Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
* * Actinides
Th Pa U
Seaborg suggested transuranium elements were a new series, akin to the rare earths.Seaborg recommended the names "lanthanides" and "actinides" for these series.
PERIODIC TABLE OF THE ELEMENTS(1948)
1A 2A 3B 4B 5B 6B 7B 8B 1B 2B 3A 4A 5A 6A 7A 8A
H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba La* Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Fr Ra Ac*** Lanthanides
Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
* * Actinides
Th Pa U Np Pu Am
Promethium was discovered in an atomic pile in Oak Ridge, Tennessee (1945)
And the transuranium elements were discovered by Seaborg and others. . . .
Today. . . .
That’s All Folks!