Good question, as this involves the interesting properties of electrons, bonds and chemical reactions and compounds.

SO₄ is bonded covalently, meaning the electrons are shared between the Sulfur and Oxygen atoms. This means that the Sulfur atom does not lose or gain any electrons. Since a normal Sulfur atom has six valence electrons, we know by Octet’s Rule that the atom would like two more electrons to fill its outer shell. However, the atom will not gain two electrons, but it will share two electrons with two neighboring oxygen atoms. These oxygen atoms form a covalent double bond with the sulfur atom.

In the formation of SO₄, the compound will gain two electrons from an outside source. These electrons go to the remaining two Oxygen atoms. These Oxygen atoms have a single bond, meaning the atoms will have six valence electrons and one shared valence electron with Sulfur. These Oxygen atoms would like one more electron to fill its outer most shell. An electron will come in to the Oxygen atom and give it a net -1 charge. This happens twice: one extra electron for each remaining Oxygen atom.

In summary, Sulfur is neutral in SO₄, and has six valence electrons. The sulfur atom shares four valence electrons with two oxygen atoms as two covalent double bonds, and shares its remaining two electrons with two oxygen atoms, forming two covalent single bonds. These two oxygen atoms each have seven valence electrons between their atom and the sulfur atom, so would like one more to fill its outer most shell. These two oxygen atoms then get an extra electron each from an outside source in a chemical reaction. The 2 electrons gained by these Oxygen atoms give SO₄ a net -2 charge.

Hope this helps to show how bonds are formed in this chemical compound!

SO₄ isn't a molecule - it's an ion with 2 negative charges: SO₄^[-2] - it comes from chemicals like sulfuric acid, which has 2 H+ hydrogen ions to neutralize it = H₂SO₄. The answer to your question is Yes and No. The sulfur has a partial positive charge. And the oxygen has a partial negative charge.

You can check Helen's answer here, if you want more info. I didn't like any of the 3 answers, so I added a 4th:

No; the oxygen that the sulfur is bound to are negatively-charged. The sulfur is covalently bounded to the oxygen. Two of the oxygens have one negative charge each.

Although the overall charge of SO₄ is 2^-, the sulfur atom is in the +6 state and two of the oxygens are in the -2 state.