Editing Metalloid (section)

==Properties==
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 [[oxide]]s. Most of their other physical and chemical properties are [[properties of metals, metalloids and nonmetals|intermediate in nature]].

===Compared to metals and nonmetals===
{{Main|Properties of metals, metalloids and nonmetals}}
Characteristic properties of metals, metalloids, and nonmetals are summarized in the table.<ref>[[#Kneen1972|Kneen, Rogers & Simpson, 1972, p.&nbsp;263]]. Columns 2 and 4 are sourced from this reference unless otherwise indicated.</ref> Physical properties are listed in order of ease of determination; chemical properties run from general to specific, and then to descriptive.

{|class="wikitable"
|+Properties of metals, metalloids and nonmetals
|- valign=top
! scope="col" style="width:10em;" | Physical property
! scope="col" style="width:20em;" | Metals
! scope="col" style="width:20em;" | Metalloids
! scope="col" style="width:20em;" | Nonmetals
|- valign=top
| scope="row"| Form
| solid; a few liquid at or near room temperature ([[gallium|Ga]], [[mercury (element)|Hg]], [[rubidium|Rb]], [[caesium|Cs]], [[francium|Fr]])<ref>[[#Stoker2010|Stoker 2010, p.&nbsp;62]]; [[#Chang2002|Chang 2002, p.&nbsp;304]]. Chang speculates that the melting point of francium would be about 23&nbsp;°C.</ref>{{refn|1=[[Copernicium]] is reportedly the only metal thought to be a gas at room temperature.<ref>[[#NS1975|New Scientist 1975]]; [[#Soverna2004|Soverna 2004]]; [[#Eichler2007|Eichler et al. 2007]]; [[#Austen2012|Austen 2012]]</ref>|group=n}}
| solid<ref name="Rochow 1966, p.4">[[#Rochow1966|Rochow 1966, p.&nbsp;4]]</ref>
| majority gaseous<ref>[[#Hunt2000|Hunt 2000, p.&nbsp;256]]</ref>
|- valign=top
| scope="row"| Appearance
| lustrous (at least when freshly fractured)
| lustrous<ref name="Rochow 1966, p.4"/>
| several colourless; others coloured, or metallic grey to black
|- valign=top
| scope="row"| [[Plasticity (physics)|Plasticity]]
| typically elastic, ductile, malleable
| often brittle<ref name=McQuarrie85>[[#McQuarrie1987|McQuarrie & Rock 1987, p.&nbsp;85]]</ref>
| often brittle
|- valign=top
| scope="row"| [[Electrical conductivity]]
| good to high{{refn|1=Metals have electrical conductivity values of from 6.9 × 10<sup>3</sup>&nbsp;S•cm<sup>−1</sup> for [[manganese]] to 6.3 × 10<sup>5</sup> for [[silver]].<ref>[[#Desai1984|Desai, James & Ho 1984, p.&nbsp;1160]]; [[#Matula1979|Matula 1979, p.&nbsp;1260]]</ref>|group=n}}
| intermediate<ref>[[#Choppin1972|Choppin & Johnsen 1972, p.&nbsp;351]]</ref> to good{{refn|1=Metalloids have electrical conductivity values of from 1.5 × 10<sup>−6</sup>&nbsp;S•cm<sup>−1</sup> for boron to 3.9 × 10<sup>4</sup> for arsenic.<ref>[[#Schaefer1968|Schaefer 1968, p.&nbsp;76]]; [[#Carapella1968|Carapella 1968, p.&nbsp;30]]</ref> If selenium is included as a metalloid the applicable conductivity range would start from ~10<sup>−9</sup> to 10<sup>−12</sup>&nbsp;S•cm<sup>−1</sup>.<ref name="Kozyrev"/>|group=n}}
| poor to good{{refn|1=Nonmetals have electrical conductivity values of from ~10<sup>−18</sup>&nbsp;S•cm<sup>−1</sup> for the elemental gases to 3 × 10<sup>4</sup> in graphite.<ref>[[#Bogoroditskii1967|Bogoroditskii & Pasynkov 1967, p.&nbsp;77]]; [[#Jenkins1976|Jenkins & Kawamura 1976, p.&nbsp;88]]</ref>|group=n}}
|- valign=top
| scope="row"| [[Band structure]]
| metallic ([[bismuth|Bi]] = semimetallic)
| are semiconductors or, if not ([[arsenic|As]], [[antimony|Sb]] = semimetallic), exist in semiconducting forms<ref>[[#Hampel1976|Hampel & Hawley 1976, p.&nbsp;191]]; [[#Wulfsberg2000|Wulfsberg 2000, p.&nbsp;620]]</ref>
| semiconductor or [[Insulator (electricity)|insulator]]<ref name=Swalin>[[#Swalin1962|Swalin 1962, p.&nbsp;216]]</ref>
|- valign=top
! scope="col" style="width:10em;" | Chemical property
! scope="col" style="width:20em;" | Metals
! scope="col" style="width:20em;" | Metalloids
! scope="col" style="width:20em;" | Nonmetals
|- valign=top
| General chemical behaviour
| metallic
| nonmetallic<ref>[[#Bailar1989|Bailar et al. 1989, p.&nbsp;742]]</ref>
| nonmetallic
|- valign=top
| scope="row" |[[Ionization energy]]
| relatively low
| intermediate ionization energies,<ref>[[#Metcalfe1974|Metcalfe, Williams & Castka 1974, p.&nbsp;86]]</ref> usually falling between those of metals and nonmetals<ref>[[#Chang2002|Chang 2002, p.&nbsp;306]]</ref>
| relatively high
|- valign=top
| scope="row" |[[Electronegativity]]
| usually low
| have electronegativity values close to 2<ref>[[#Pauling1988|Pauling 1988, p.&nbsp;183]]</ref> (revised Pauling scale) or within the range of 1.9–2.2 (Allen scale)<ref name="Mann">[[#Mann2000|Mann et al. 2000, p.&nbsp;2783]]</ref>{{refn|1=Chedd<ref>[[#Chedd1969|Chedd 1969, pp.&nbsp;24–25]]</ref> defines metalloids as having electronegativity values of 1.8 to 2.2 ([[Allred-Rochow scale]]). He included boron, silicon, germanium, arsenic, antimony, tellurium, polonium, and [[astatine]] in this category. In reviewing Chedd's work, Adler<ref>[[#Adler1969|Adler 1969, pp.&nbsp;18–19]]</ref> described this choice as arbitrary, as other elements whose electronegativities lie in this range include [[copper]], silver, phosphorus, mercury, and bismuth. He went on to suggest defining a metalloid as "a semiconductor or semimetal" and to include bismuth and selenium in this category.|group=n}}
| high
|- valign=top
| scope="row" |When mixed<br/>with metals
| give [[alloy]]s
| can form alloys<ref>[[#Hultgren1966|Hultgren 1966, p.&nbsp;648]]; [[#Young2000|Young & Sessine 2000, p.&nbsp;849]]; [[#Bassett1966|Bassett et al. 1966, p.&nbsp;602]]</ref>
| ionic or [[interstitial compound]]s formed
|- valign=top
| scope="row" |[[Oxide]]s
| lower oxides [[base (chemistry)|basic]]; higher oxides increasingly [[acid]]ic
| amphoteric or weakly acidic<ref>[[#Rochow1966|Rochow 1966, p.&nbsp;4]]; [[#Atkins2006|Atkins et al. 2006, pp.&nbsp;8, 122–23]]</ref>
| acidic
|}
The above table reflects the hybrid nature of metalloids. The properties of ''form, appearance'', and ''behaviour when mixed with metals'' are more like metals. ''Elasticity'' and ''general chemical behaviour'' are more like nonmetals. ''Electrical conductivity, band structure, ionization energy, electronegativity,'' and ''oxides'' are intermediate between the two.