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

$$\ce{SO4^2-}$$ is a polyatomic ion as well as a nonpolar covalent compound. How can it be ionic and covalent at the same time?
Same applies to sulfite $$\ce{SO3^2-}$$. 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. Dec 22, 2016 at 7:50

Sulfate is tetrahedral, so each individual dipole vector would be opposed and cancelled, making the overall molecule non-polar (in the same way that this question and answer about $$\ce{CO2}$$ details).