Question

The number on an ion or a radical indicates the__________ of that radical.

Answer 1

Valency

• The combining power (or capacity) of an element is known as its valency.
• The number on an ion or a radical indicates the valency of that radical.

Example

• The valency of sodium ion$\left({\mathrm{Na}}^{+}\right)$, potassium ion$\left({\mathrm{K}}^{+}\right)$ is $+1$.
• The valency of magnesium ion$\left({\mathrm{Mg}}^{2+}\right)$, and calcium ion$\left({\mathrm{Ca}}^{2+}\right)$ is $+2$.

So, the number on an ion or a radical indicates the valency of that radical.