Dimitri Ivanovitch Mendeleev
(1834 - 1907)
Dimitri Mendeleev was the youngest of a very large family born to Ivan and Marya Mendeleev. Ivan died at a young age, leaving Marya to support the family. She did so for years by managing the family owned Korniliev glass factory in Aremziansk. In addition to showing interest in math and physics in school, Dimitri also learned about glass and glass blowing. Despite many setbacks in his life, he managed to attend the university in St. Petersburg eventually earning a Ph.D. and becoming a Professor of Chemistry at the Technological Institute in St. Petersburg.
Mendeleev's greatest achievement was the discovery of the Periodic Law which led to the development of the Periodic Table. Before Mendeleev's Periodic Table, the elements were distinguished from one another by only their atomic weight. Mendeleev began to notice that the chemical properties of the elements were grouped into families. The following patterns in the combining ratios of the elements were notes by Mendeleev:
- 1) The elements lithium (Li), sodium (Na), and potassium (K) all formed oxides in the ration of two atoms per oxygen atom: R2O
2) The elements beryllium (Be), magnesium (Mg), and calcium (Ca) all formed oxides of one atom per oxygen atom: RO
3) Boron (B) and aluminum (Al) formed R2O3
4) Carbon (C) and silicon (Si) formed RO2
By recognizing the patterns of the combining ratios (valency), Mendeleev created a table organized by placing elements with similar valency in the same group. Within the group, the elements were arranged in order of their atomic mass. He left gaps in the table and claimed that undiscovered elements would fit into these spaces. This was confirmed with the discovery of three of his predicted elements; gallium, germanium and scandium.
| Reihen |
— R2O |
— RO |
— R2O3 |
RH4 RO2 |
RH3 R2O5 |
RH2 RO3 |
RH R2O7 |
— RO4 |
| 1 | H = 1 | |||||||
| 2 | = 7
|
= 9,4
|
= 11
|
= 12
|
= 14
|
= 16
|
= 19
|
|
| 3 | = 23 | = 24 | = 27,3 | = 28 | = 31 | = 32 | = 35,5 | |
| 4 | = 39 | = 40 | = 44 | = 48 | = 51 | = 52 | = 55 | = 56, =59 =59, =63 |
| 5 | ( = 63) | = 65 | = 68 | = 72 | = 75 | = 78 | = 80 | |
| 6 | = 85 | = 87 | ? = 88 | = 90 | = 94 | = 96 | = 100 | =104, =104 =106, =108 |
| 7 | = 108 | = 112 | = 113 | = 118 | = 122 | = 125 | = 127 | |
| 8 | = 133 | = 137 | ? = 138 | ? = 140 | — | — | — | — |
| 9 | (—) | — | — | — | — | — | — | |
| 10 | — | — | ? = 178 | ? = 180 | = 182 | = 184 | — | =195, =197, =198, =199 |
| 11 | ( = 199) | = 200 | = 204 | = 207 | = 208 | — | — | |
| 12 | — | — | — | — | — | — |
Later, due to his political views, Mendeleev resigned from the university and was appointed Director of the Bureau of Weights and Measures until his death from pneumonia in 1907.
HOW TO USE THE MODERN INTERACTIVE TABLE
In the modern periodic table this is a common representation for the element Carbon:
Just by looking in the box there are several pieces of information that can be determined. The C is they symbol for carbon. All elements have a 1 or 2 letter symbol. If the symbol has 2 letters, the second is lowercase; the first is always uppercase. The number above the C is atomic number. The atomic number is the number of protons in the element and defines what element it is and determines its chemical behavior. Below the symbol is the atomic mass of the element in atomic mass units, 12.01 in this case. The atomic mass is the average mass of the various isotopes of the element.
INTERACTIVE FEATURES
Each element in the Periodic Table is linked to a text file containing detailed information about that element. This file can be reached from the Periodic Table, from the TOC, and also from the Interactive Table Properties of the Elements.
The live Properties of the Elements table is an enormous collection of property data for each of the elements. The properties are data and keyword searchable as well as being displayed in an interactive table. The table is searchable and able to be sorted and contains links to the detailed text files.