Here's why:

* Metalloids are elements that have properties of both metals and nonmetals. They are often semiconductors, meaning they can conduct electricity under certain conditions.

* Arsenic is a metalloid that is brittle, shiny, and a poor conductor of electricity. It's used in various applications, including semiconductors, pesticides, and alloys.

* Silicon is another metalloid known for its use in semiconductors, solar cells, and glass. It is a hard, brittle, and lustrous element.

While they share the metalloid classification, they have distinct properties and uses.