Editing Metalloid (section)

{{short description|Chemical element with metallic and nonmetallic properties}}
{{Periodic table (metalloid)}}
{{Sidebar periodic table|expanded=metalicity}}
A '''metalloid''' is a [[chemical element]] which has a preponderance of [[material property|properties]] in between, or that are a mixture of, those of [[metal]]s and [[Nonmetal (chemistry)|nonmetal]]s. The word metalloid comes from the [[Latin language|Latin]] ''metallum'' ("metal") and the [[Greek language|Greek]] ''oeides'' ("resembling in form or appearance").<ref>[[Metalloid#OED1989|''Oxford English Dictionary'' 1989, 'metalloid']]; [[Metalloid#GGH2003|Gordh, Gordh & Headrick 2003, p.&nbsp;753]]</ref> There is no standard definition of a metalloid and no complete agreement on which elements are metalloids. Despite the lack of specificity, the term remains in use in the literature.

The six commonly recognised metalloids are [[boron]], [[silicon]], [[germanium]], [[arsenic]], [[antimony]] and [[tellurium]]. Five elements are less frequently so classified: [[carbon]], [[aluminium]], [[selenium]], [[polonium]] and [[astatine]]. On a standard periodic table, all eleven elements are in a diagonal region of the [[p-block]] extending from boron at the upper left to astatine at lower right. Some periodic tables include a [[dividing line between metals and nonmetals]], and the metalloids may be found close to this line.

Typical metalloids have a metallic appearance, may be brittle and are only fair [[electrical conductor|conductors of electricity]]. They can form [[alloy]]s with [[metal]]s, and many of their other [[physical property|physical properties]] and [[chemical property|chemical properties]] are intermediate between those of metallic and nonmetallic elements. They and their compounds are used in alloys, biological agents, [[catalyst]]s, [[flame retardant]]s, [[glass]]es, [[optical storage]] and [[optoelectronics]], [[pyrotechnics]], [[semiconductor]]s, and electronics.

The term ''metalloid'' originally referred to [[nonmetal]]s. Its more recent meaning, as a category of elements with intermediate or hybrid properties, became widespread in 1940–1960. Metalloids are sometimes called semimetals, a practice that has been discouraged,<ref name=Atkins2010p20/> as the term ''[[semimetal]]'' has a more common usage as a specific kind of [[electronic band structure]] of a substance. In this context, only [[arsenic]] and [[antimony]] are semimetals, and commonly recognised as metalloids.