Final answer:
Sulfur is a nonmetallic element with 6 valence electrons. It can exhibit various oxidation numbers, typically -2 when forming sulfides with metals, but it can show positive oxidation states such as +4 or +6 when combined with more electronegative elements like oxygen or fluorine.
Step-by-step explanation:
Sulfur is a nonmetallic element belonging to group 16 on the periodic table. It has 6 valence electrons and exhibits various oxidation numbers depending on the substance it combines with. When sulfur reacts with metals, it often forms sulfides (S²⁻), taking on an oxidation state of -2. In compounds like sulfur dioxide (SO₂), sulfur has an oxidation number of +4 based on the fact that each oxygen has an oxidation number of -2 and the total must add up to zero for a neutral compound.
Furthermore, in other compounds, such as sulfur hexafluoride (SF₆), sulfur has an oxidation state of +6 to balance the six fluorine atoms, each having an oxidation number of -1. Likewise, in sulfate ion (SO₄²⁻), sulfur exhibits a +6 oxidation state to balance the charge on the four oxygen atoms.
Therefore, the oxidation number of sulfur can vary, but in binary metal sulfides, we typically see sulfur with an oxidation number of -2. However, when bonded to more electronegative elements like oxygen and fluorine, sulfur can have positive oxidation states such as +4 (sulfur dioxide) or +6 (sulfur hexafluoride and sulfate ion).