Here's why:

* Physical Properties: Phosphorus is a solid at room temperature and has a waxy appearance. It's brittle, not malleable or ductile like metals.

* Chemical Properties: Phosphorus is a poor conductor of heat and electricity, unlike metals. It tends to gain electrons to form negative ions, a characteristic of nonmetals.

* Location on the Periodic Table: Phosphorus is located in Group 15 (also called the pnictogens) of the periodic table, which is primarily composed of nonmetals.

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