Final answer:
The chemical formula for sulfur trioxide is SO₃, consisting of one sulfur atom and three oxygen atoms.
Step-by-step explanation:
The correct chemical formula for sulfur trioxide is SO₃. This compound consists of one sulfur atom and three oxygen atoms. The nomenclature system ensures that each compound has a unique name that reflects its composition. Therefore, based on the name sulfur trioxide, we can determine that the chemical compound contains sulfur and three oxygen atoms, leading to the formula SO₃.