Question

Find out the valency of oxygen and aluminium.

Answer 1

Valency of an Atom

1. The valency of an atom is the number of electrons that are required to be added or removed from the outermost shell of an atom to complete its octet.
2. Valency is also known as the combining capacity of an element.
3. Valency is different for different periods but can be the same for a group,
4. Due to the inert pair effect of the d-bock in the last 2 periods, the value of valency also varies in a group.

Valency of Oxygen

Electronic Configuration of$\mathrm{O}$ = $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^4$ with atomic number $8$.

1. Oxygen has$6$ electrons in its valence shell.
2. Two more electrons are required to complete the octet.
3. So, the valency of oxygen is $2$.

Valency of Aluminium

Electronic Configuration of $\mathrm{Al}$= $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^1$with atomic number $13$

1. Aluminium has$3$ electrons in its valence shell.
2. It is easy for Aluminium to donate $3$ electrons rather than taking$5$ electrons to complete its octet.
3. So, the valency of Aluminium is $3$.

Hence, the Valency of $\mathrm{O}$= $2$ and Valency of $\mathrm{Al}$= $3$