Development of the Periodic Chart

Dmitri Mendeleeff

timeline

Dmitri Ivanovich Mendeléeff (1834 to 1907) as born in Tobol'sk in western Siberia, the youngest child of a very large family (some report 14 to 17 children).  His maternal grandparents had established the first glassworks and paper mill in Tobol'sk.  While still young, Dmitri's father lost his job as director of the Tobol'sk gymnasium due to cataracts in both eyes.  To provide for the family his mother, Maria, founded and successfully managed her own glassworks in a neighboring village.  Dmitri excelled in mathematics, physics, and history.  He graduated from the gymnasium shortly after his father died of tuberculosis and the glassworks burned to the ground.  Maria secured horses and journeyed the great distance to Moscow with her two youngest children, hoping to enroll Dmitri in University.  Failing to do so, she continued to Petrograd (now St. Petersburg) where a friend of her late husband arranged for Dmitri to begin work in the department of physics and mathematics at the Central Pedagogic Institute.  A few months later Maria also died.  When dying, she said Refrain from illusions, insist on work, and not on words.  Patiently search divine and scientific truth.

When Mendeléeff graduated from the Pedagogical Institute, he received a gold medal for excellence in scholarship.  In his undergraduate thesis on mineral analysis he compiled and systematized large amounts of chemical data and began considering the problem of similarity of substances.  Between 1859 and 1861 he worked with Regnault in Paris and Bunsen in Heidelberg.  The instruments he purchased in Western Europe enabled him to measure the properties of substances with very good precision.  He too attended the first International Chemical Congress in September 1860 at Karlsruhe and had been impressed by the paper on determining atomic weights Stanislao Cannizzaro distributed.  Mendeléeff immediately wrote his teacher in Petrograd (which was publish in a Petrograd newspaper and a Moscow journal) noting that Cannizzaro corrected inconsistencies in existing atomic weights of metals so that atomic heats divided by a substance's number of atoms resulted in a constant (about 6 to 7) in accord with Dulong and Petit.  Before returning to Russia he visited the new oil fields in Pennsylvania.  Upon his return to Petrograd in early 1861, he was granted his doctorate and appointed professor of chemistry at the Technological Institute.  His doctoral thesis was On Compounds of Alcohol with Water.  Now teaching, he completed his first chemistry textbook, Organic Chemistry.  It was well received and in 1862 he received the Demidov Prize for the outstanding book.

In the Fall of 1867 he became professor of general chemistry at the University of Petrograd.  Not finding any suitable Russian textbook to recommend to students, he began to write The Principles of Chemistry, the first portion which was published in May or June 1868.  Mendeléeff searched for an organizing principle so that the mass of chemical knowledge would not be chaotic.  While the law of definite chemical compounds had persuasively proven the atomic theory, a whole group of so-called indefinite compounds and solutions seemed to refute the atomic theory.  Distinct chemical elements with well defined atomic weights clearly existed, but the actual existence and nature of atoms was more problematic.  On February 17, 1869 he completed his first periodic table which in March he presented in a paper to the Russian Chemical Society on The Relation of the Properties to the Atomic Weights of the Elements.  He fell ill and N.A.Menshutkin read it for him.  In this paper he presented a periodic table, boldly noted the periodic relationship of chemical formulas to atomic weights, noted some elements had atomic weights that needed correction, and forecast that new elements would be discovered to fit vacant spaces in his table.  The same month Mendeléeff published the second volume of The Principles of Chemistry, Chapters 12-22.  Paradoxically, it appears Mendeléeff found the weight of elements was an invariable characteristic that provided an organization for studying chemistry free from employing the notion of atoms that was shrouded in controversy.

Distribution of the Elements by their Atomic Weights
From Mendeléeff's abstract Zeit. Chem., 1869, 5
 
 
 
 
 
 
 
 
 
Typische
H = 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Elemente
Li = 7
Be = 9,4
B = 11
C = 12
N = 14
O = 16
F = 19
 
 
 
 
 
 
 
 
 
 
Na = 23
Mg = 24
Al = 27,4
Si = 28
P = 31
S = 32
Cl = 35,5
K = 39
Ca = 40
-
Ti = 48
V = 51
Cr = 52
Mn = 55
Fe = 56
Cu = 63
Ni = Co = 59
Cu = 63
Zn = 65,2
-
-
As = 75
Se = 79,4
Br = 80
Rb = 85,4
Sr = 87,6
? Yt = 88?
Zr = 90
Nb = 94
Mo = 96
-
Ru = 104,4
Rh = 104,4
Pd = 106,6
Ag = 108
Cd = 112
In = 113
Sn = 118
Sb = 122
Te = 128?
J = 127
Cs = 133
Ba = 137
Di = 138?
Ce = 140?
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Er = 178?
? La = 180?
Ta = 182
W = 186
-
Os = 199
Ir = 198
Pt = 197,4
Au = 197?
Hg = 200
Ti = 204
Pb = 207
Bi = 210
-
-
-
-
-
Th = 231
-
U = 240
-
-
-
-
-
-
-
-
-
-
-

The paper included eight conclusions including:
The properties of the elements show a periodic change with increasing atomic weight.
Most common elements in nature have low atomic weights.
The three elements (those right of aluminum and silicon, and below calcium) are required but not yet discovered.
Several atomic weights appear to be in error and need correction.

At the end of March 1970 the third volume was published and the final two volumes were published in February 1871.  In July 1871 Mendeléeff published a comprehensive paper on the periodic law.  But it was in February 1869 that Mendeléeff first realized that atomic weights, not valence should be the guiding principle for chemistry.  In subsequent editions, eight in all, he significantly revised the structure of the textbook to be in more accord with the periodic law with each new edition.

Mendeléeff's Predictions for Three Missing Elements
Predicted Properties Properties as Discovered
Eka-Aluminum (as predicted 1871)
Atomic Weight: 68
Low melting point
Density: 5.9 g/mL
Formula of Oxide: Ea2O3
Chloride: Ea2Cl6
Gallium (discovered 1875)
Atomic Weight: 69.3
Melting point: 30.15°C
Density: 5.93 g/mL
Oxide: Ga2O3
Chloride: Ga2Cl6
Eka-Boron (as predicted 1871)
Atomic Weight: 44
Oxide: Eb2O3 with density 3.5 g/mL
Scandium (discovered 1879)
Atomic Weight: 44.7
Oxide: Sc2O3, density 3.8 g/mL
Eka-Silicon (as predicted 1871)
Atomic Weight: 70
Grey, difficult to melt
Oxide: EbO2
Chloride: EbCl4 , boiling ~100°C
Fluorides: EbF4 & M2EbF6
Germanium (discovered 1886)
Atomic Weight: 72.04
Grey-white; melts ~900°C
Oxide: GeO2
Chloride: GeCl4 , boils 86°C
Fluorides: GeF4 •3H2O & M2GeF6

In 1871 Mendeléeff produced a form of the periodic chart horizontal like Meyers, predicted atomic weights for nine missing elements, and gave detailed predictions of the properties for eka-Boron, eka-Aluminum, and eka-Silicon.

The Atomic Weights of the Elements
Distribution of the elements in Periods
From Mendeléeff's Principles of Chemistry, Vol. 1 (updated)
LargePeriods
GroupsHigher
salt-
forming
oxides
Typical or
1st small
Period
1st2nd3rd4th5th
I.
II.
III.
IV.
V.
VI.
VII.

VIII.

I.
II.
III.
IV.
V.
VI.
VII.
R2O
RO
R2O3
RO2
R2O5
RO3
R2O7
 /     
|     
 \     
R2O
RO
R2O3
RO2
R2O5
RO3
R2O7
Li = 7
Be = 9
B = 11
C = 12
N = 14
O = 16
F = 19



H 1. Na 23
Mg = 24
Al = 27
Si = 28
P = 31
S = 32
Cl = 35.5
K 39
Ca 40
Sc 44
Ti 48
V 51
Cr 52
Mn 55
Fe 56
Co 58.5
Ni 59
Cu 63
Zn 65
Ga 70
Ge 72
As 75
Se 79
Br 80
Rb 85
Sr 87
Y 89
Zr 90
Nb 94
Mo 96
--
Ru 103
Rh 104
Pd 106
Ag 108
Cd 112
In 113
Sn 118
Sb 120
Te 125
I 127
Cs 133
Ba 137
La 138
Ce 140
--
--
--
--
--
--
--
--
--
--
--
--
--
--
--
Yb 173
--
Ta 182
W 184
--
Os 191
Ir 193
Pt 196
Au 198
Hg 200
Tl 204
Pb 206
Bi 208
--
--
--
--
--
Th 232
--
Ur 240
--
--
--
--
--
--
--
--
--
--
--
2nd small
period
1st 2nd 3rd 4th 5th
LargePeriods

In 1871 Mendeléeff left blanks for 32 missing elements.

Mendeléeff
predicted
Element
found
Date
Discovered
eka B (44) Sc (45) 1879
eka Al (68) Ga (70) 1875
eka Si (72) Ge (73) 1886
eka Cs (175) - -
dwi Cs (220) Fr (223) 1939
eka Nb (146) - -
eka Ta (235) Pa (231) 1917
eka Mn (100) Tc (98) 1937
tri Mn (190) Re (186) 1925

Unlike the traditional elements which provided a wealth of properties to organize, only a few of the rare earths were known making interpolation of their number and properties difficult.  Besides eka Cs and eka Nb above, there were a number of the 32 predicted elements that Mendeléeff predicted in error.  In 1889 Mendeléeff predicted details for dwi Te which was discovered in 1898 and called Polonium by the Curies.

Despite Mendeléeff's believe that some atomic weights were in error, more careful measurements of Ar (39.95) and K (39.10), Co (58.93) and Ni (58.69), and Te (127.6) and I (126.91) left them inverted.

The establishment of the periodic system was regarded by most chemists as a discovery of the highest importance.  Stanislao Cannizzaro had provided the key to establishing atomic weights with Avogadro's hypothesis.  A number of chemists had found patterns in those weights.  Mendeléeff had recognized the periodic table's broad power to organize all that was know about the chemical elements and their compounds plus the value for predicting yet undiscovered substances and their properties.  Meyers had first used the pattern to merely suggest the difficulty with simple atoms but quickly appreciated and popularized the broad significance suggested by Mendeléeff.  Alexandre Emile Béguyer de Chancourtois (1820 - 1886), professor of geology at the École des Mines in Paris, described to the French Academy of Sciences in 1882-3 his vis Tellurique (earthy screw) plotting atomic weights on a helix with 16 atomic mass units per turn.  (However Chancourtois' screw does NOT align any chemical families; he found no chemical periodicity.)  William Odling (1829 - 1921), a reader in chemistry at St. Bartholomew's Hospital in London had suggested an arithmetical seriation of atomic weights in 1864.  Gustavus Detlef Hinrichs (1836 - 1923), professor at the University of Iowa, published in 1867 a radial periodic chart with each family arranged along spokes with the monomer of all atoms, an Urstoff called pantogen with a weight of half hydrogen's at the center.  (But only non-metals had arcs of similar atomic weights.)  But it was Mendeléeff's broad appreciation for the significance and practical use of the periodic law for all elements that won him acknowldgement as its discoverer.

But the failure to immediately find the expected underlying unity of matter implied by the periodic table became frustrating to many chemists.  No Urstoff was found, yet there must be an explanation why the properties of elements reoccurred periodically.

In 1904, Mendeléeff extrapolated two elements lighter than Hydrogen, and several heavy elements.  Few of these predictions were accurate.

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