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

Elements recognized as metalloids

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• t
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	13	14	15	16	17
2	B Boron	C Carbon	N Nitrogen	O Oxygen	F Fluorine
3	Al Aluminium	Si Silicon	P Phosphorus	S Sulfur	Cl Chlorine
4	Ga Gallium	Ge Germanium	As Arsenic	Se Selenium	Br Bromine
5	In Indium	Sn Tin	Sb Antimony	Te Tellurium	I Iodine
6	Tl Thallium	Pb Lead	Bi Bismuth	Po Polonium	At Astatine
Common: (86–99%): B, Si, Ge, As, Sb, Te   Sometimes (40–49%): Po, At   Less common (24%): Se   Rarely (8–10%): C, Al
This piece of the periodic table shows chemical elements that are sometimes called metalloids. It is based on how often they appear in 196 different lists of metalloids [en].[n 1] The staircase-shaped line is a typical example of the arbitrary metal–nonmetal dividing line found on some periodic tables.

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

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  Antimony, a semimetal, can be found naturally in the earth.
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  Arsenic is another semimetal that is very toxic.
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  Tellurium in a bottle. Tellurium sometimes is found naturally.
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  Germanium in a tube. Germanium can be used to make semiconductors. Silicon is used more.
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  Silicon crystal. Silicon is used to make semiconductors.
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  Boron in a tube. Boron is very hard.

Notes

1. For a related commentary see also: Vernon RE 2013, 'Which Elements Are Metalloids?', Journal of Chemical Education, vol. 90, no. 12, pp. 1703–1707, doi:10.1021/ed3008457