# Bond angles in sulfate

My chemical bonding professor says that the $\ce{O-S-O}$ bond angles in $\ce{SO4^2-}$ are ideal (109.5°).

Why? Is this because all bonds are equivalent, and electron distribution is shared among all oxygens?

• Exactly. You may think of it as a superposition of resonance structures with all possible combinations of $\ce{S=O}$ and $\ce{S-O-}$. – Ivan Neretin Sep 25 '15 at 5:29

• Yes, all the bonds are equal in $\ce{SO4^2-}$, but thinking of them as bond order 1.5 is no longer accepted as correct. – Jan Sep 25 '15 at 13:52