Question

How can we learn Valencies of elements 1 to 20

Answer 1

The International Union of Pure and Applied Chemistry defines valence as “The maximum number of univalent atoms (originally hydrogen or chlorine atoms) that may combine with an atom of the element under consideration, or with a fragment, or for which an atom of this element can be substituted.”

Going by this definition, the valencies of the first 20 elements are:

H 1; He 0; Li 1; Be: 2; B: 3; C: 4, N: 5; O: 2; F: 1; Ne: 0

Na: 1: Mg: 2; Al: 3; Si: 4; P: 5; S: 6; Cl: 7; Ar: 0

K: 1; Ca: 2

Answer 2

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