# How can sulfate be nonpolar covalent if it is a polyatomic ion?

SO$_{4}$$^{2-} is a polyatomic ion as well as a nonpolar covalent compound. How can it be ionic and covalent at the same time? Same goes with SO_{3}$$^{2-}$ (Sulfite). It's a polyatomic ion as well as a polar covalent bond. How?

• A great deal of compounds are ionic and covalent at the same time. There is nothing strange or unusual about it. – Ivan Neretin Dec 22 '16 at 7:50