Question

Find out the valency and electrovalency shown by the: (a) Sodium atom

Answer 1

Valency:

The combining capacity of the atom of an element with the atoms of other elements in order to acquire eight electrons in its outermost shell is known as valency.

Example:

1. Consider a Sodium atom $\mathbf{\left(}\mathbf{Na}\mathbf{\right)}$ having atomic number $11$. Thus, the number of electrons in a Sodium atom are $11$.
2. The electronic configuration of Sodium is $(2,8,1)$.
3. In order to acquire eight electrons in the outermost shell, Sodium atom loses $1$ electron from the outermost shell.
4. Thus, the valency of Sodium is $1$.

Electrovalency:

When an element combines with another element by losing and gaining electrons to form a compound, its valency is called electrovalency.

Example:

1. Sodium atom $\mathbf{\left(}\mathbf{Na}\mathbf{\right)}$ has atomic number $11$. Thus, the number of electrons in a Sodium atom are $11$.
2. The electronic configuration of Sodium is $(2,8,1)$.
3. In order to acquire eight electrons in the outermost shell i.e. to attain nearest noble gas configuration, Sodium atom loses $1$ electron from the outermost shell.
4. This leads to formation of Sodium ion having one unit of positive charge $\left({\mathrm{Na}}^{+}\right)$.
5. Thus, the electrovalency of Sodium is $+1$.