19.2: Nonmetals
I. Properties of Nonmetals
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Nonmetals are the opposite of metals:
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Usually gases or brittle solids at room temperature
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Not flexible
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Do not conduct heat or electricity well (insulators)
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Generally not shiny
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Humans are made mostly of nonmetals: 65% O, 18% C, 10% H, 3% N, 4% others
II. Bonding in Nonmetals
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Most nonmetals can form both ionic and covalent compounds:
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Receive electrons in an ionic bond
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Share electrons in a covalent bond
III. Hydrogen
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The only nonmetal found on the left side of the periodic table (group 1)
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Odorless, colorless gas
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Makes up 90% of the elements in the universe
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Exists as a diatomic molecule: two atoms of the same element in a covalent bond
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Highly reactive
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Can share its one electron (covalent bond with nonmetals) or receive one electron (ionic bond with
metals)
IV. The Halogens
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Group 17: F, Cl, Br, I, At
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Exist as diatomic molecules (except At)
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F & Cl are gases
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Br is a liquid
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I & At are solids
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Vividly colored in gas form: Cl2 is greenish yellow, Br2 is reddish-orange, & I2 is violet
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Very reactive
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Form salts when bonded to a metals
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F is the most chemically active of all the elements
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Uses of halogens:
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F: compounds prevent tooth decay; acid can etch and frost glass
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Cl: compounds disinfect water; bleaches; household cleaners; most abundant halogen
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Br: only liquid nonmetal; compounds used as dyes in cosmetics
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I: changes directly from a solid to a gas when heated (sublimation); essential nutrient
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At: radioactive; no known uses
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Cl, Br, & I can all be extracted from seawater
V. The Noble Gases
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Group 18: He, Ne, Ar, Kr, Xe, Rn
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All exist as isolated atoms (not diatomic)
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Very unreactive; no naturally occurring compounds containing noble gases
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Compounds of Xe & Kr with F have been made in the lab
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Used in neon lights, lasers, as an anti-corrosive in lightbulbs, and in welding