Valence theory

The valence theory explained how elements combine with fixed numbers of other atoms according to specific rules. The notion of valence imposed a new kind of order on the elements, because valence seemed to change regularly with the arrangement of atoms in the periodic table.
 Edward Frankland England 1852 Valence theory

The valence theory explained how elements combine with fixed numbers of other atoms according to specific rules. The notion of valence imposed a new kind of order on the elements, because valence seemed to change regularly with the arrangement of atoms in the periodic table.