nonmetal


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nonmetal,

chemical elementelement,
in chemistry, a substance that cannot be decomposed into simpler substances by chemical means. A substance such as a compound can be decomposed into its constituent elements by means of a chemical reaction, but no further simplification can be achieved.
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 possessing certain properties by which it is distinguished from a metalmetal,
chemical element displaying certain properties by which it is normally distinguished from a nonmetal, notably its metallic luster, the capacity to lose electrons and form a positive ion, and the ability to conduct heat and electricity.
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. In general, this distinction is drawn on the basis that a nonmetal tends to accept electrons and form negative ionsion,
atom or group of atoms having a net electric charge. Positive and Negative Electric Charges

A neutral atom or group of atoms becomes an ion by gaining or losing one or more electrons or protons.
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 and that its oxide is acidic. Nonmetals are poor conductors of heat and electricity (see conductionconduction,
transfer of heat or electricity through a substance, resulting from a difference in temperature between different parts of the substance, in the case of heat, or from a difference in electric potential, in the case of electricity.
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) and do not have the luster of metals. Arsenic, antimony, selenium, and tellurium exhibit both nonmetallic and metallic properties and are called metalloids. Unlike the metals, which are all solids (with the exception of mercury) under ordinary conditions of temperature and pressure, the nonmetals appear in all three states. Argon, chlorine, fluorine, helium, hydrogen, krypton, neon, nitrogen, oxygen, and xenon are normally gases. Bromine is a liquid. Boron, carbon, iodine, phosphorus, silicon, and sulfur are solids. Certain of them, e.g., boron, carbon, iodine, silicon, and sulfur, form crystals, as do the metals. In hardness they vary considerably. Carbon in its allotropic form, the diamond, is the hardest element known. With the exception of carbon, sulfur, nitrogen, oxygen, and the inert gases—argon, helium, krypton, neon, and xenon—the nonmetals do not occur uncombined in nature, but exist in numerous relatively abundant compounds, among which are the oxides, halides (binary halogen compounds), sulfides, carbonates, nitrates, phosphates, silicates, and sulfates. With a few exceptions, the nonmetallic elements are important chiefly for their compounds. For the properties and uses of specific nonmetals, see the separate articles on these elements.

nonmetal

any of a number of chemical elements that form negative ions, have acidic oxides, and are generally poor conductors of heat and electricity
References in periodicals archive ?
This statement is false because carbon is a nonmetal and has the highest melting point on the chart.
The development of designs for metal building systems that can accept nonmetal outer coverings has aided the penetration of metal buildings in markets where aesthetic concerns are important, such as in commercial and institutional settings.
In a shallow 1- to 1-1/2-quart nonmetal baking dish, stir oil, onion, curry, ginger, and cinnamon to mix.
* National District Council Safety Competition for Surface Metal/ Nonmetal (Group III): Greater Northeast District Council.
The new diesel regulations will affect 145 underground coal mines employing nearly 15,000 miners and 196 underground metal and nonmetal mines employing nearly 19,000 miners.
The rescue team from Doe Run Peru's Cobriza Division, representing Peru, achieved a very creditable third place in the International Metal and Nonmetal Mine Rescue Contest held in July in Las Vegas.
In a 2-quart glass measuring cup or nonmetal (microwave-safe) bowl, combine sugar, butter, and milk.
* Underground Nonmetal: Kerford Limestone--Kerford Limestone Co.
Foxleigh's sale helps make good on a projection by South African-headquartered Anglo earlier this year that it would cut its portfolio from 45 assets to 16 and concentrate on its core metal/ nonmetal assets.
Twenty-eight of those standards apply to coal mines, and 19 to metal and nonmetal mines.
The machine has a 7.5 sec chip-to-chip tool change time with high speed traverse rates of up to 945 ipm for X and Y axes and 787 ipm for Z axis and 3600 deg/min for the A and B axes reducing nonmetal cutting time.
Set butterflied fish pieces on a 9- to 10inch nonmetal plate and drizzle evenly with orange juice and soy.