Question

What is the difference between valency and valence electrons?

Answer 1

Difference between valency and valence electrons

Serial number	Valency	Valence electrons
1	The combining power (or capacity) of an element is known as its valency.	The electrons that are present in outermost or valence shell of an atom are called valence electrons.
2	Example: Sodium(Na) $\mathrm{Electronic}\mathrm{}\mathrm{configuration}\mathrm{:}\mathrm{}\mathrm{1}{\mathrm{s}}^{\mathrm{2}}\mathrm{2}{\mathrm{s}}^{\mathrm{2}}\mathrm{2}{\mathrm{p}}^{\mathrm{6}}\mathrm{}\mathrm{3}{\mathrm{s}}^{\mathrm{\text{1}}}$ Now, Sodium atom loses one electron to attain noble gas electronic configuration. Hence, the valency of Sodium is $+1$.	Example: Sodium(Na) $\mathrm{Electronic}\mathrm{}\mathrm{configuration}\mathrm{:}\mathrm{}\mathrm{1}{\mathrm{s}}^{\mathrm{2}}\mathrm{2}{\mathrm{s}}^{\mathrm{2}}\mathrm{2}{\mathrm{p}}^{\mathrm{6}}\mathrm{}\mathrm{3}{\mathrm{s}}^{\mathrm{\text{1}}}$ Now, the outermost shell = 3s The electrons in outermost shell = 1 So, valence electrons in Sodium = 1