Final answer:
The compound with two atoms of sulfur and two atoms of oxygen is named sulfur dioxide, and its molecular formula is SO2.
Step-by-step explanation:
The compound containing two atoms of sulfur and two atoms of oxygen is called sulfur dioxide. The molecular formula for sulfur dioxide is SO2. To write this formula and name, we follow the system of chemical nomenclature which combines numerical prefixes with the elements present. Since the compound contains two oxygen atoms, we use the prefix 'di-' to clarify the number of oxygen atoms.
The 'di-' is combined with 'oxide', the anion formed from oxygen, resulting in 'dioxide'. Therefore, combining the name of the first element, sulfur, with 'dioxide' gives us sulfur dioxide. Note that the prefix 'mono-' is not used for the first element when there is only one atom of it in the compound.