how to calculate valency of any compound - Science - Atoms and Molecules

Question

how to calculate valency of any compound ????

Animesh Paul · Accepted Answer

Solution:
When we move from left to right in the periodic table valency
increases But after 4, it decreases also
The electrons present in the last shell determine the valency of
a particular element
If the number of valence electrons ≤4: valency = number of
valence electrons
If the number of valence electrons >4: valency = 8 - number
of valence electrons
For e g

Group in the periodic table

Number of valency electrons

valency

1

2

13

3

14

4

15

5

3, 5

16

6

2, 6

17

7

1, 7

18

8

0, 8

For your convenience, I am providing two examples to show how
the valency of any element can be found
If you consider the element aluminum and try to write its
electronic configuration, then it is 2, 8, 3 the valency is equal
to 3
However, for element oxygen having electronic configuration 2, 6
the valency is 8 - 6 = 2