Question

How many valence electrons does Bromine have?

Answer 1

Valence electrons:

• The electrons which are distributed in the outermost shell of the atom are called valence electrons.

Valence electrons in a Bromine atom:

• The atomic number of Bromine$\left(\mathrm{Br}\right)$ is 35.
• The electronic configuration of Bromine$\left(\mathrm{Br}\right)$ can be written as $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}4{\mathrm{s}}^{2}3{\mathrm{d}}^{10}4{\mathrm{p}}^5$
• The valence electrons are the sum of the electrons in the outermost shell, that is two $4\mathrm{s}$ electrons and five $4\mathrm{p}$ electrons which gives a total of seven valence electrons.

Therefore, the valence electron in a Bromine$\left(\mathrm{Br}\right)$ atom is 7.