jan 1, 1947 - Mendeleev published
the 13th (last copy) of
"Principles of Chemistry"
Description:
The first part of the text was about the chemistry of halogens. Next, he covered the chemistry of the metallic elements in order of combining power. While sorting out a problem "Mendeleev noticed patterns in the properties and atomic weights of halogens, alkali metals and alkaline metals." He then created a card for each 63 elements which included the element's symbol, atomic weight and its characteristic chemical and physical properties.He then arranged it by atomic mass and created the periodic table. At times he placed elements in different parts of the table if they do not have similar mass but have other similar characteristics. Then he changed the mass to something that is similar to its new placement.
17 elements had to move. With gaps in the table he put predicted unknown elements.
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