A metalloid is a chemical element with properties that are a mixture of both metals and nonmetals. There is no standard definition of a metalloid, nor is there complete agreement as to which elements are appropriately classified as such. Despite this lack of specificity, the term remains in use in the literature of chemistry.
The six commonly recognized metalloids are:
Most of these elements are important industrial materials, being used to make transistors and other semiconductor devices, ceramics, solar batteries and certain polymers.
Metalloids are also known as semimetals.
Metalloids are a group of elements that share characteristics of both metals and nonmetals, and are typically semi-conductors, which means that they both insulate and conduct electricity. This semi-conducting property makes metalloids very useful as a computer chip material. Metalloids typically conduct heat and electricity better than nonmetals, but not as well as metals. They tend to behave intermediately during chemical reactions, taking electrons from most metals and losing electrons to most nonmetals.
Metalloids usually look like metals but behave largely like nonmetals. Physically, they are shiny, brittle solids with intermediate to relatively good electrical conductivity and the electronic band structure of a semimetal or semiconductor. Chemically, they mostly behave as (weak) nonmetals, have intermediate ionization energies and electronegativity values, and amphoteric or weakly acidic oxides. They can form alloys with metals. Most of their other physical and chemical properties are intermediate in nature.
As a result, metalloids have become important for many industrial applications. Metalloids are most often used in the chemical, electronics and alloy industries. For example, germanium and silicon are an integral part of semiconductors and solid-state electronics. Metallic antimony is widely used in alloys, while chemical forms of antimony are used as a flame-retardant ingredient in plastics and other materials. Tellurium is used as an alloying agent to improve the machinability of certain steels, as well as in electro-thermal and photovoltaic applications due to its unique thermal properties. Boron is used as a dopant in semiconductors, as a bonding agent in permanent, rare earth magnets, as well as in abrasive and chemical substances.