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Chemical Symbols and Formulas

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Compounds are composed of more than one element. Their formulas have more than one type of symbol showing the different elements that compose that compound. Remember...

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Constructed from the symbols of the elements composing the substances. EXAMPLE: NaCl is made of sodium (symbol = Na) and chlorine (symbol = Cl) Chemical Formulas Na Cl

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A subscript is the little number that shows how many of each kind of atom are in the compound They are written to the lower right of the element symbol EXAMPLE: H 2 OHydrogen How many? Oxygen How many? When no subscript is written, it is a 1 Subscripts 2 1 O H H

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The number that comes before the chemical formula and indicates the number of molecules present. EXAMPLE: 6H 2 O6 tells you there are six molecules of water Coefficients O H H O H H O H H O H H O H H O H H

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CompoundFormulaCommon Name Sodium ChlorideNaClTable salt Dihydrogen MonoxideH2OH2OWater GlucoseC 6 H 12 O 6 Simple sugar Oxygen gasO2O2 Carbon dioxideCO 2 Carbon dioxide Nitrogen gasN2N2 Chemical Formulas you must know: