Question

The electrons present in the ___________ shell of an atom are called valence electrons.

Answer 1

Valence shell:

• The outermost shell of an atom is called the Valence shell.
• For example, sodium atom. The atomic number is 11.
• The electron configuration is ${}_{11}\mathrm{Na}=\underset{\mathrm{K}}{2},\underset{\mathrm{L}}{8},\underset{\mathrm{M}}{1}$
• So, M is a valence shell here.

Valence electrons:

• The electrons present in the outermost shell (valence shell) are called valence electrons.
• For example, Magnesium atom. The atomic number is 12.
• The electron configuration is ${}_{12}\mathrm{Mg}=\underset{\mathrm{K}}{2},\underset{\mathrm{L}}{8},\underset{\mathrm{M}}{2}$
• So, the number of valence electrons is 2.

Hence, the electrons present in the outermost shell of an atom are called valence electrons.