Here's why:

* Location on the Periodic Table: Helium is located in Group 18 (VIIIa), also known as the noble gases. Noble gases are all nonmetals.

* Physical Properties: Helium is a colorless, odorless, tasteless gas at room temperature. It is a very poor conductor of heat and electricity, which are characteristics of nonmetals.

* Chemical Properties: Helium is extremely unreactive. It rarely forms chemical bonds with other elements, which is another defining trait of nonmetals.

Let me know if you have any other questions!