Define the following terms with examples: Trivalent

Trivalent:

When an atom gains or loses three electron from its outermost shell in order to acquire eight electrons in its outermost shell its valency becomes three. Such atoms having valency three are known as trivalent.

Examples:

Aluminium $\mathbf{\left(}\mathbf{Al}\mathbf{\right)}$:

1. Aluminium metal has atomic number $13$. Thus, the electronic configuration of Aluminium is $(2,8,3)$.
2. Aluminium atom loses three valence electrons to acquire eight electrons in the outermost shell.
3. Thus, valency of Aluminium is $3$ and it is known as trivalent.

Nitrogen $\mathbf{\left(}\mathbf{N}\mathbf{\right)}$:

1. Nitrogen, non-metal has atomic number $7$. Thus, the electronic configuration of Nitrogen is $(2,5)$.
2. Nitrogen atom gains three electrons to acquire eight electrons in the outermost shell.
3. Thus, valency of Nitrogen is $3$ and it is known as trivalent.