Question

An ion with 7+ charge contains 18 electrons. Which ion is it?

Answer 1

Manganese(VII).

Explanation:

Since the ion has `18` electrons in its `+7` oxidation state, in its neutral form, it must have `18+7=25` electrons.

That also means that it has `25` protons when it's an element. On the periodic table, the element with `25` protons is manganese `(Mn)`.

So, the ion here is manganese(VII) or `Mn^(7+)`. Compounds containing this ion are called permanganates.