Difference between revisions of "Nonmetal" - New World Encyclopedia

Revision as of 23:51, 23 July 2008

Nonmetal is a term used in chemistry when classifying the chemical elements. On the basis of their general physical and chemical properties, every element in the periodic table can be termed either a metal or a non-metal. (A few elements with intermediate properties are referred to as metalloids.)

The elements generally regarded as nonmetals are:

hydrogen (H)
In Group 14: carbon (C)
In Group 15 (the pnictogens): nitrogen (N), phosphorus (P)
Several elements in Group 16, the chalcogens: oxygen (O), sulfur (S), selenium (Se)
All elements in Group 17 - the halogens
All elements in Group 18 - the noble gases

There is no rigorous definition for the term "nonmetal" - it covers a general spectrum of behaviour. Common properties considered characteristic of a nonmetal include:

poor conductors of heat and electricity when compared to metals
they form acidic oxides (whereas metals generally form basic oxides)
in solid form, they are dull and brittle, rather than metals which are lustrous, ductile or malleable
usually have lower densities than metals
they have significantly lower melting points and boiling points than metals
non-metals have high electronegativity

Only eighteen elements in the periodic table are generally considered nonmetals, compared to over eighty metals, but nonmetals make up most of the crust, atmosphere and oceans of the earth. Bulk tissues of living organisms are composed almost entirely of nonmetals. Most nonmetals form monatomic or diatomic molecules in their elemental state, unlike metals which (in their elemental state) do not form molecules at all.

Metallisation at huge pressures

Nevertheless, even these 20 elements tend to become metallic at large enough pressures (see nearby periodic table at ~300 GPa).

ar:لا فلز ast:Non metal bs:Nemetal bg:Неметал ca:No metall cs:Nekov cy:Anfetel da:Ikke-metal de:Nichtmetalle et:Mittemetallid el:Αμέταλλα es:No metal eo:Nemetalo eu:Ez-metal fr:Non-métal ko:비금속 id:Nonlogam is:Málmleysingi it:Non metallo he:אל-מתכת jv:Nonlogam lmo:Minga metàj hu:Nemfémek mk:Неметал ms:Bukan logam nl:Niet-metaal ja:非金属元素 no:Ikke-metall nn:Ikkje-metall nds:Nichmetall pl:Niemetale pt:Não-metal ro:Nemetal qu:Mana q'illay ru:Неметаллы sq:Jometalet simple:Nonmetal sk:Nekov sl:Nekovina sr:Неметали fi:Epämetalli sv:Icke-metall th:ธาตุอโลหะ vi:Phi kim tr:Ametal uk:Неметали yi:נישט-מעטאל zh:非金属元素

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-Together with the [[metal]]s and [[metalloid]]s, a '''nonmetal''' is one of three categories of [[chemical element]]s as distinguished by [[ionization]] and [[chemical bonding|bonding]] properties.  These properties stem from the fact that nonmetals are highly [[electronegative]], i.e. they gain [[valence electron]]s from other atoms more readily than they give them up.
+'''Nonmetal''' is a term used in [[chemistry]] when classifying the [[chemical element]]s. On the basis of their general physical and chemical properties, every element in the [[periodic table]] can be termed either a [[metal]] or a non-metal. (A few elements with intermediate properties are referred to as [[metalloid]]s.)
-The nonmetals are [[Halogen]]s, [[Noble gas]]es and the following elements in order of [[atomic number]] (nonmetals as chemical series):
+The elements generally regarded as nonmetals are:
 * [[hydrogen]] (H)
-* [[carbon]] (C)
+* In Group 14: [[carbon]] (C)
-* [[nitrogen]] (N)
+* In Group 15 (the [[pnictogens]]): [[nitrogen]] (N), [[phosphorus]] (P)
-* [[oxygen]] (O)
+* Several elements in Group 16, the [[chalcogens]]: [[oxygen]] (O), [[sulfur]] (S), [[selenium]] (Se)
-* [[phosphorus]] (P)
+* All elements in Group 17 - the [[halogen]]s
-* [[sulfur]] (S)
+* All elements in Group 18 - the [[noble gas]]es
-* [[selenium]] (Se)
+<!-- Deleted image removed: [[Image:Nonmetals at 3 million atmospheres.png|thumb|400px|A possible form of periodic table at a pressure of three million atmospheres. It is possible that all the elements become metallic at sufficiently high pressure. The elements C, N, F, Cl, Ne, Ar, Kr, and He (in grey) have not yet been investigated at sufficiently high pressures to achieve metallisation.<ref>{{citejournal|journal=ChemPhysChem|volume=3|issue=1|pages=53 - 56|published=2002-01-14|author=Peter P. Edwards, Friedrich Hensel|title=Metallic Oxygen|publisher=WILEY-VCH-Verlag|location=Weinheim, Germany|year=2002|url=http://www3.interscience.wiley.com/cgi-bin/abstract/89014409/ABSTRACT?CRETRY=1&SRETRY=0|accessdate=2008-01-08}}</ref>]] —>
-Most nonmetals are found at the upper right of the [[periodic table]].  The exception is [[hydrogen]], which is usually placed at the upper left with the [[alkali metal]]s, but behaves like a nonmetal under most conditions.  Unlike metals, which are electrically conductive, a nonmetal may be an [[insulator]] or a [[semiconductor]]. Nonmetals may form [[ionic bond]]s with metals by gaining [[electron]]s, or [[covalent bond]]s with other nonmetals. The [[oxide]]s of nonmetals are [[acid]]ic.
+There is no rigorous definition for the term "nonmetal" - it covers a general spectrum of behaviour. Common properties considered characteristic of a nonmetal include:
+* poor conductors of [[heat]] and [[Electrical conductivity|electricity]] when compared to metals
+* they form [[acid]]ic [[oxide]]s (whereas metals generally form [[Base (chemistry)|basic]] oxides)
+* in solid form, they are dull and [[brittle]], rather than metals which are [[Lustre (mineralogy)|lustrous]], [[ductile]] or [[malleable]]
+* usually have lower [[density|densities]] than metals
+* they have significantly lower [[melting point]]s and [[boiling point]]s than metals
+* non-metals have high [[electronegativity]]
-There are only twelve known nonmetals, compared to over eighty metals, but nonmetals make up most of the [[earth]], particularly in the outer layers.  [[Organism]]s are composed almost entirely of nonmetals. Many nonmetals (hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, and iodine) are [[diatomic]], and most of the rest are otherwise [[polyatomic molecule|polyatomic]].
+Only eighteen elements in the periodic table are generally considered nonmetals, compared to over eighty metals, but nonmetals make up most of the crust, atmosphere and oceans of the [[earth]]. Bulk tissues of living [[organism]]s are composed almost entirely of nonmetals. Most nonmetals form [[monatomic]] or [[diatomic molecule]]s in their elemental state, unlike metals which (in their elemental state) do not form molecules at all.
+===Metallisation at huge pressures===
+Nevertheless, even these 20 elements tend to become metallic at large enough pressures (see nearby periodic table at ~300 GPa).
-<br/>
+==See also==
-{{PeriodicTablesFooter}} [[Category:Periodic table]] <br/>
+{{reflist}}
-[[Category:Physical sciences]]
+{{PeriodicTablesFooter}}
-[[Category:Chemistry]]
+{{compact periodic table}}
 [[Category:Nonmetals|*]]
+[[Category:Periodic table]]
+{{Link FA|lmo}}
 [[ar:لا فلز]]
+[[ast:Non metal]]
+[[bs:Nemetal]]
+[[bg:Неметал]]
 [[ca:No metall]]
-[[de:Nichtmetall]]
+[[cs:Nekov]]
+[[cy:Anfetel]]
+[[da:Ikke-metal]]
+[[de:Nichtmetalle]]
+[[et:Mittemetallid]]
+[[el:Αμέταλλα]]
 [[es:No metal]]
 [[eo:Nemetalo]]
+[[eu:Ez-metal]]
 [[fr:Non-métal]]
 [[ko:비금속]]
+[[id:Nonlogam]]
 [[is:Málmleysingi]]
 [[it:Non metallo]]
-[[he:אל מתכת]]
+[[he:אל-מתכת]]
+[[jv:Nonlogam]]
+[[lmo:Minga metàj]]
+[[hu:Nemfémek]]
+[[mk:Неметал]]
+[[ms:Bukan logam]]
 [[nl:Niet-metaal]]
-[[nds:Nichtmetalle]]
 [[ja:非金属元素]]
 [[no:Ikke-metall]]
 [[nn:Ikkje-metall]]
+[[nds:Nichmetall]]
 [[pl:Niemetale]]
 [[pt:Não-metal]]
-[[th:อโลหะ]]
+[[ro:Nemetal]]
+[[qu:Mana q'illay]]
+[[ru:Неметаллы]]
+[[sq:Jometalet]]
+[[simple:Nonmetal]]
+[[sk:Nekov]]
+[[sl:Nekovina]]
+[[sr:Неметали]]
+[[fi:Epämetalli]]
+[[sv:Icke-metall]]
+[[th:ธาตุอโลหะ]]
+[[vi:Phi kim]]
 [[tr:Ametal]]
+[[uk:Неметали]]
+[[yi:נישט-מעטאל]]
 [[zh:非金属元素]]
-{{credit|25342097}}