Question

How do you find the total number of electrons for a Polyatomic ion?

Answer 1

Find the valence electrons that each atom would have, just like for a neutral molecule, then add or remove electrons depending on the charge of the ion.

For example, the carbonate ion, \(CO_3^{-2}\) has 4 electrons from the carbon, 6 electrons from each oxygen (x3), AND two more electrons because it has the negative 2 charge

4 + 3(6) + 2 = 24 electrons in the Lewis structure of the carbonate ion