Question

How many electrons must be shown in the Lewis structure of the hydroxide ion, `OH^-`?

Answer 1

8 electrons.

Explanation:

Only valence electrons are shown on a Lewis structure - these are the electrons in the outermost shell of an atom. The oxygen atom has 6 valence electrons, while the hydrogen atom has just 1.

However, the hydroxide ion carries a negative charge, which means 1 extra electron has been introduced. We must add that to the valence electrons already present.

This gives a total of `6+1+1 = 8` electrons.