Glossary

A metalloid is a type of element that exhibits properties intermediate between those of metals and nonmetals. Metalloids have a unique combination of characteristics—some metallic, such as luster, electrical conductivity, and the ability to form alloys, and some nonmetallic, such as brittleness and poor heat conduction. This hybrid nature makes them extremely important in semiconductor technology, alloys, and chemical applications.

On the periodic table, metalloids typically appear along the diagonal “stair-step” line that separates metals (on the left) from nonmetals (on the right). The most commonly recognized metalloids are boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), and tellurium (Te). Some classifications also include polonium (Po) and astatine (At) depending on their behavior in chemical reactions.

Metalloids often have metallic appearance and moderate electrical conductivity, which can be adjusted by temperature, impurities, or doping—a property that makes them ideal for semiconductors. For example, silicon and germanium are the backbone of the electronics industry, used in computer chips, transistors, and solar cells. Arsenic and antimony, meanwhile, are used to modify alloys, harden lead, or enhance flame retardancy.

Chemically, metalloids can form compounds with both metals and nonmetals, and their oxides often show amphoteric behavior—meaning they can act as either acids or bases. This dual nature reflects their position between the two extremes on the periodic table.