![]() ![]() The fourteen elements that are almost always recognized as nonmetals are hydrogen, oxygen, nitrogen, and sulfur the highly reactive halogens fluorine, chlorine, bromine, and iodine and the noble gases helium, neon, argon, krypton, xenon, and radon, as listed in Hawley’s Condensed Chemical Dictionary. Īlthough Steudel, in 2020, recognised twenty-three elements as nonmetals, any such list is open to challenge. The decisions involved depend on which property or properties are regarded as most indicative of nonmetallic or metallic character. Since there is no rigorous definition of a nonmetal, some variation exists among sources as to which elements are classified as such. More generally they are deemed to lack a preponderance of metallic properties such as luster or shininess the capacity to be flattened into a sheet or drawn into a wire good thermal and electrical conductivity and the capacity to form a basic (rather than acidic) oxide. Generally, from 14 to 23 elements are recognized as nonmetals.ĭefinition and applicable elements Ī nonmetal is a chemical element that, in the broadest sense of the term, has a relatively low density and high electronegativity. ![]() Some elements have a marked mixture of metallic and nonmetallic properties, and which of these borderline cases are counted as nonmetals varies depending on the classification criteria used. While the term non-metallic dates from as far back as 1566, there is no widely agreed precise definition of a nonmetal. Nonmetallic elements are important to industries ranging from electronics and energy storage to agriculture and chemical production. Living organisms are composed almost entirely of the nonmetals hydrogen, oxygen, carbon, and nitrogen. The distinctive properties of nonmetallic elements allow for specific applications that often cannot be fulfilled by metallic elements alone. Five nonmetallic elements, hydrogen, carbon, nitrogen, oxygen and silicon, make up most of the Earth's crust, atmosphere, oceans and biosphere. Two nonmetals, hydrogen and helium, make up about 99% of ordinary matter in the observable universe by mass. Nonmetal atoms tend to attract electrons in chemical reactions and to form acidic compounds. In contrast, metals are good conductors and most are easily flattened into sheets and drawn into wires since their electrons are generally free-moving. They are usually poor conductors of heat and electricity, and brittle or crumbly when solid due to their electrons having low mobility. ▉ ▉ ▉ ▉ ▉ ▉ ▉ ▉ ▉ ▉ ▉ ▉ ▉ ▉ ▉ ▉ ▉ ▉Ī nonmetal is a chemical element that, in the broadest sense of the term, has a relatively low density and high electronegativity they range from colorless gases (like hydrogen) to shiny solids (like carbon, as graphite). Hydrogen is usually in group 1 (as in the full table below) but can be in group 17 (as in the extract above). There is no precise definition of a nonmetal which elements are counted as such varies. For nonmetallic substances, see materials science.Įxtract of periodic table showing how often each element is classified as a nonmetal:ġ4 effectively always 3 frequently 6 sometimes ( metalloids) ![]()
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