Question

how to find valency? what is the valency of (a) fluorine in CaF₂ (b)sulphur in SF₆ (c)phosphorus in PH₃ (d) carbon in CH₆ (e)nitrogen in the following compounds (i)N₂O₃ (ii)N₂O₅ (iii)NO₂ (iv)NO

Answer 1

1. Valency is the combining power or in simple words it is the number of electrons added or removes from an atom, so that the ion formed has a noble gas configuration.

2. We can find the valency as follows:

If the valence electrons less than 5,say x then, Valency = 8-x = positive
IF the valence electrons is more than five, then , Valency = x-8 = negative

3. The solutions are as follows:

(a) Valency of Fluorine is -1, since valence electron is 7, so 7-8= -1.
(b) Sulphur is +6.
(c) Phosphorous is +3.
(d) Carbon is +6.
(e) Valency of N:
(i) N₂O₃ - Valency = +3
(ii) N₂O₅ - Valency = +5
(iii) NO₂ - Valency = +4
(iv) NO - Valency = +2