Question

Give a reason for the following:

• Aluminium has positive valency.

Answer 1

Valency- It is the combining capacity of an element with other element by gaining , losing or sharing of electron to attain octet in outer most shell.

Way to find valency of an element-

1. To write electronic configuration.
2. No. of electron in the outermost shell.
3. No. of electron required to complete outermost shell.

Valency of Aluminium (Al)

1. Electronic configuration- 2,8,3
2. No. of electrons in the outermost shell- 3
3. No. of electron required to complete outermost shell- gaining 5 electrons is difficult for aluminium, so it loses 3 electrons.
4. As aluminium will lose 3 more electrons, and number of protons is more than electrons.

Hence, Aluminium has positive valency i.e. 3