history of the periodic table of the elements (chem 1360) part 3

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 K39

Ca40

"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


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!


1 2 3 4 5 6 7 8 1 2 3 4 5 6 7


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)


1 2 3 4 5 6 7 8 1 2 3 4 5 6 7


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!


1 2 3 4 5 6 7 8 1 2 3 4 5 6 7


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

Nd144145

147Sm148

Eu151152

155Gd156159160

Tb163

Ho165

Er166167

Tm171

Yb173176

178Ta

182W

184190Os191

Ir193

Pt195

9 Au197

Hg200

Tl204

Pb207

Bi209212214

10218220

Ra225230

Th233235

U239

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).


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

0

Moseley — 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. . . .



H He

Li Be B C N O F Ne



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



H He

Li Be B C N O F Ne



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.



H He

Li Be B C N O F Ne



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!

history of the periodic table of the elements (chem 1360) part 3

Documents

chemical congress

cannizzaros principle

chemical equivalents

lavoisiers elements

atomic weights berzelius

chemical reactions

chemical formulas

elements chem