# Question 54872

However, when Oxygen bonds with other atoms, it gains two electrons and thus gains a charge of $2 -$. This is because atoms naturally want their outer shells to be filled, and in Oxygen's case the filling number is 8 electrons. This means Oxygen needs to gain 2 electrons to have a full outer shell, and since electrons have a negative charge, and 2 are gained, Oxygen gains a charge of O"" ^(2-)#.