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Jöns Jacob Berzelius

The Origins of Stoichiometry (Jöns Jacob Berzelius)

Jöns Jacob Berzelius was so impressed with the work of Richter and Dalton that he analyzed 2000 compounds to provide the experimental basis for the atomic theory. Working in a laboratory with facilities no more elaborate than a kitchen, Berzelius prepared and purified the necessary reagents, developed the techniques to perform the analyses, and collected data on the relative weights of atoms of 43 elements.

Berzelius also introduced the symbolism with which chemical formulas are still written, although he wrote the numbers that specify the ratio of the elements as superscripts (H2O) rather than as subscripts (H2O). The table below illustrates the power of Berzelius's work by comparing some of his results with the most recently published data. In most cases, Berzelius's data agree with those obtained with modern instrumentation. Where significant differences exist, they are the result of assumptions that Berzelius had to make about the formulas of the compounds he analyzed.

Comparison of Berzelius's Atomic Weights with Modern Values

Element Berzelius's Atomic Weights (1826) Modern Atomic Weights (1983)
Hydrogen 0.998 1.008
Carbon  12.25 12.01
Nitrogen  14.16 14.01
Oxygen   16.00 16.00
Sulfur 32.19 32.06
Chlorine  35.41 35.45
Calcium  40.96 40.08
Sodium 46.54 22.99
Iron 54.27 55.85
Chromium  56.29 52.01
Copper  63.31 63.54
Potassium  78.39 39.10
Strontium 87.56 87.62
Iodine  123.00 126.90
Barium  137.10 137.34
Gold  198.88 196.97
Mercury  202.53 200.59
Lead  207.12 207.19
Silver  216.26 107.87


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