Question

Consider the elements Na, Mg and Al and their respective atomic numbers $11$, $12$ and $13$. What are the valence electrons in each element?

Answer 1

Electronic configuration:

1. The arrangement of electrons in the atomic orbitals of elements is characterized by electronic configuration.
2. The atomic numbers are filled in K shell which can bear up to 2 electrons, L shell which can bear up to 8 electrons and M shell which can bear up to 18 electrons and so on.

Valence electrons:

1. Valence electrons are the electrons that are available in the outermost shell of an atom.
2. The electronic configuration of Sodium $\left(\mathrm{Na}\right)$, Magnesium $\left(\mathrm{Mg}\right)$ and Aluminium $\left(\mathrm{Al}\right)$ can be obtained as:

$$\begin{gathered} \mathrm{Na}-2,8,1 \\ \mathrm{Mg}-2,8,2 \\ \mathrm{Al}-2,8,3 \end{gathered}$$

Therefore, the valence electron of $\mathrm{Na},\mathrm{Mg},\mathrm{Al}$ are 1,2 and 3 respectively.