Metalloid
A metalloid is a type of chemical element. Metalloids are elements that have the properties of both metal and non-metal elements. It might be shiny, but brittle. It might be dull, but conduct electricity.
Metalloids are also sometimes called semimetals, especially in older sources. The term "metalloid" is preferred because "semimetal" has a different meaning in physics.
The most common metalloid is silicon. Silicon has electrical conductivity between metals and nonmetals. It is a semiconductor.
Elements
Template:Periodic table (metalloid)
There is no single definition of a "metalloid", and different sources include different elements in the category. The periodic table here shows the dividing line between metals and nonmetals, with colored cells showing elements that are sometimes called metalloids.
The six green elements - boron, silicon, germanium, arsenic, antimony, and tellurium - are the most common group of metalloids, and are almost always called such.
Polonium and astatine are both very radioactive synthetic elements, so it is hard to study their chemistry or physical properties. Selenium has a mixture of properties of metals and nonmetals, and is sometimes counted as a metalloid. Carbon and aluminium are usually considered a nonmetal and a metal, but are metalloids according to some specific definitions.
Specific definitions of a metalloid can also include elements not in this chart.
Gallery
Antimony, a semimetal, can be found naturally in the earth.
Arsenic is another semimetal that is very toxic.
Tellurium in a bottle. Tellurium sometimes is found naturally.
Germanium in a tube. Germanium can be used to make semiconductors. Silicon is used more.
Silicon crystal. Silicon is used to make semiconductors.
Boron in a tube. Boron is very hard.
Metalloid Media
Copper-germanium alloy pellets, likely ~84% Cu; 16% Ge. When combined with silver the result is a tarnish resistant sterling silver. Also shown are two silver pellets.
Arsenic trioxide or white arsenic, one of the most toxic and prevalent forms of arsenic. The antileukaemic properties of white arsenic were first reported in 1878.
Optical fibers, usually made of pure silicon dioxide glass, with additives such as boron trioxide or germanium dioxide for increased sensitivity
Archaic blue light signal, fuelled by a mixture of sodium nitrate, sulfur, and (red) arsenic trisulfide
Boron, shown here in the form of its β-rhombohedral phase (its most thermodynamically stable allotrope)
Arsenic, sealed in a container to prevent tarnishing
