Question

similarly find out the valencies of the first twenty elements

Answer 1

The total number of electrons gain or lose by an element to complete its octate or duplet is called valency.

Valency of first 20 elements:-

H = 1

He = 0

Li = 1

Be = 2

B = 3

C = 4

N = 3

O = 2

F = 1

Ne = 0

Na = 1

Mg = 2

Al = 3

Si = 4

P = 3

S = 2

Cl = 1

Ar = 0

K = 1

Ca = 2

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Answer 2

1,0,1,2,3,4,3,2,1,0,1,2,3,4,3,2,1,0,1,2 respectively are the valencies of first 20 elements