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.
In a shallow 1- to 1-1/2-quart nonmetal baking dish, stir oil, onion, curry, ginger, and cinnamon to mix.
Unlike examinations of surface and underground coal mines, which must be performed by a "certified person," examinations of metal and nonmetal mines must be performed by a "competent person.
The final rule to protect underground metal and nonmetal miners will establish an "interim" DPM concentration limit of 400 [micro]g/[m.
On the whole, the nation's roughly 11,000 metal and nonmetal mines are reporting more fatalities and at a faster pace since 1992.
In a 2-quart glass measuring cup or nonmetal (microwave-safe) bowl, combine sugar, butter, and milk.
Nine each were killed in coal mining and metal and nonmetal mining accidents.
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.
Softer, shorter and circular, nonmetal cleats are growing in popularity from the San Fernando Valley to the fairways of Winged Foot Golf Club in Mamaroneck, N.
Set butterflied fish pieces on a 9- to 10inch nonmetal plate and drizzle evenly with orange juice and soy.
Department of Labor's Mine Safety and Health Administration (MSHA) announced it is extending the effective date of the agency's final rule on Examinations of Working Places in Metal and Nonmetal Mines until Oct.
The metal and nonmetal mining industries established a record low fatality rate of 0.