Here's why:

* Properties: Sulfur is a brittle, yellow solid at room temperature. It's a poor conductor of heat and electricity.

* Location on Periodic Table: Sulfur is located in Group 16 (also known as the chalcogens) of the periodic table, which is predominantly made up of nonmetals.

* Reactivity: Sulfur tends to gain electrons to form negative ions (anions), which is a characteristic of nonmetals.

Let me know if you have any other questions about sulfur or the periodic table!