Question

Define the valency of an element. Calculate the valency of nitrogen in ${\mathrm{N}}_2{\mathrm{O}}_5$

Answer 1

Valency

• Atoms combine to form molecules. The combining tendency of atoms is defined in terms of their valencies.
• The number of hydrogen atoms or chlorine atoms or double the number of oxygen atoms which combines with one atom of the element is called its valency.

Valency of nitrogen in ${\mathrm{N}}_2{\mathrm{O}}_5$

The valency of nitrogen ${\mathrm{N}}_2{\mathrm{O}}_5$ can be obtained as:

• Number of oxygen atoms combined with two atoms of $\mathrm{N}$ = 5
• So, the number of oxygen atoms combined with one atom of $\mathrm{N}$= $\frac{5}{2}$

As per definition,

• Valency of $\mathrm{N}$ in ${\mathrm{N}}_2{\mathrm{O}}_5$ = Number of oxygen atoms that combine with atoms of $\mathrm{N}$

= 2 x $\frac{5}{2}$

Thus, the valency of nitrogen in ${\mathrm{N}}_2{\mathrm{O}}_5$ = 5