Nonmetal, or non-metal, 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 nonmetal. (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 (with the exception of Carbon)
- non-metals have high electronegativity
They also have a negative valence, compared to the positive valence of metals.
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 are monatomic noble gases or form diatomic molecules in their elemental state, unlike metals which (in their elemental state) do not form molecules at all.
Periodic tables Layouts List of elements by Groups Other element categories Blocks Periods Book:Periodic table · Category:Periodic table · Portal:Chemistry Periodic table H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Rf Db Sg Bh Hs Mt Ds Rg Cn Uut Uuq Uup Uuh Uus Uuo Alkali metals Alkaline earth metals Lanthanides Actinides Transition metals Other metals Metalloids Other nonmetals Halogens Noble gases Unknown chem. properties Large version
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Nonmetal — Non met al, n. (Chem.) Any one of the set of elements which, as contrasted with the metals, possess, produce, or receive, acid rather than basic properties; a metalloid; as, oxygen, sulphur, and chlorine are nonmetals. [1913 Webster] … The Collaborative International Dictionary of English
nonmetal — [nänmet′ l] n. any of those elements lacking the characteristics of a metal; specif., any of the electronegative elements (e.g., oxygen, carbon, nitrogen, fluorine, phosphorus, sulfur) whose oxides form acids and stable compounds with hydrogen… … English World dictionary
nonmetal — nemetalas statusas T sritis chemija apibrėžtis Cheminis elementas, kuriam būdingas didelis elektrinis neigiamumas, blogas elektrinis ir šiluminis laidumas. atitikmenys: angl. non metal; nonmetal rus. неметалл … Chemijos terminų aiškinamasis žodynas
nonmetal — noun Date: circa 1864 a chemical element (as boron, carbon, or nitrogen) that lacks the characteristics of a metal … New Collegiate Dictionary
nonmetal — /non met l/, n. Chem. 1. an element not having the character of a metal, as carbon or nitrogen. 2. an element incapable of forming simple positive ions in solution. [1865 70; NON + METAL] * * * ▪ chemistry substance that does not exhibit… … Universalium
nonmetal — noun an element, such as phosphorus or chlorine, that does not have the chemical or physical properties of a metal … Wiktionary
nonmetal — non·met·al ( )nän met əl n a chemical element (as boron, carbon, or nitrogen) that lacks the characteristics of a metal and that is able to form anions, acidic oxides, acids, and stable compounds with hydrogen * * * non·met·al (non metґəl)… … Medical dictionary
nonmetal — nÉ‘n metl / nÉ’n n. chemical element without metallic properties … English contemporary dictionary
nonmetal — non·metal … English syllables
nonmetal — non•met•al [[t]nɒnˈmɛt l[/t]] n. 1) chem. an element not having the character of a metal, as carbon or nitrogen 2) chem. an element incapable of forming simple positive ions in solution • Etymology: 1865–70 non me•tal′lic məˈtæl ɪk adj … From formal English to slang