Question

How do you determine the valency of elements in a compound ? What are the steps involved in this process with an example Na20 ?​

Answer 1

Explanation:

The elements in a group tend to have similar physical and chemical properties because of their similar outer shell electron structure.

1. Valency of first group elements is 1 and that of oxygen is 2. Hence, oxide of first group is X

2

O.

Eg; H O

1 2 (Criss cross)

H

2

O is the oxide.

2. Group 13 has a valency of 3 and that of halogen is 1. Hence, halide of group 13 is MX

3

Eg; B Cl

3 1 (Criss cross)

BCl

3

is the halide.

3. The valency of the Group 2 elements is +2 and that of Group 16 elements is -2. Group 2 loses electrons and group 16 accepts electrons. Hence, compounds formed are MY.

Eg; Mg O

2 2 (Criss cross)

MgO is the compound.