Here's why:

* Electronegativity: Oxygen is more electronegative than sulfur, meaning it has a stronger pull on shared electrons. However, the difference in electronegativity between the two elements is not large enough to create an ionic bond.

* Sharing electrons: Instead, they will share electrons to achieve a stable octet configuration, resulting in a covalent bond.

Specifically, the bond between sulfur and oxygen is a polar covalent bond. This means that the shared electrons are drawn more towards the oxygen atom, creating a slightly negative charge on the oxygen and a slightly positive charge on the sulfur.