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Unformatted text preview: on Nitrite ion Nitrate ion Phosphate ion Hydrogen phosphate ion Sulfate ion Formula NH4+ CN OH ClO ClO4 NO2 NO3 PO43 HPO42 SO42 Typical NH4Cl NaCN NaOH NaClO NaClO4 NaNO2 NaNO3 Na3PO4 Na2HPO4 Na2SO4 From above table,we can see that: 1. Polyatomic anions are more common than polyatomic cations.The most familiar polyatomic cation is the Ammonium ion, NH4+ . 2. Very few polyatomic anions carry the ide ending in their names.Of those listed ,only CN- ,OH- do.The common endings are ite and ate, and some names carry prefixes,hypo or per. 3. An element common to many polyatomic anions is oxygen,usually in combination with another nonmetal.Such anions are called oxoanions. 4. Certain nonmetals from a series of oxoanions containing different numbers of oxygen atoms.Their names are related to the oxidation states of the nonmetal atom to which the O atoms are bonded,ranging from hypo(lowest) to per(highest) according to the scheme. 5. All the common oxoanions of Cl,Br,and I carry a charge of 1-. 6. Some series of oxoanions also contain varying numbers of H atoms and are named accordingly HPO42- is hydrogen phosphate ion. 7. The prefix thio signifies that a sulfur atom has been substituted for an oxygen atom. Thiosulfate ion (S2O32) has two S and three O atoms. Oxoacids The majority of acids are ternary compounds.They contain three different elements-hydrogen,and two other nonmetals.If one of the nonmetals is oxygen,the acis is called an oxoacid.The table for naming oxoacids is similar to that outlined for oxoanions,except that the ending ous is used instead of ite and ic instead of ate.
Nomenclature of Some Oxoacids and Their Salts
Oxidation state Cl: +1 Cl: +5 Cl: +7 N: +3 N: +5 S: +6 S: +4 Formula of acid HClO HClO3 HClO4 HNO2 HNO3 H2SO4 H2SO3 Name of acid Formula of salt Name of salt Sodium hypochlorite Sodium chlotate Sodium perchlorate Sodium nitrite Sodium nitrate Sodium sulfate Sodium sulfite Hypochlorous acid NaClO Chloric acid Perchloric acid Nitrous acid Nitric acid Sulfuric acid Sulfurous acid NaClO3 NaClO4 NaNO2 NaNO3 NaSO4 NaSO3 Applying Various Rules in Naming Compounds. Name the compounds (a)ClO2; (b)Ca(H2PO4)2 Solution (a) Both Cl and O are nonmetals.ClO2 is a binary molecular compound called chlorine dioxide. ClO2 is not chlorite ion,it carries no nte charge (b) The polyatomic anion H2PO4 is dihydrogen phosphate ion.Two of these ions are present for every Ca2+ ion in the compound calcium dihydrogen phosphate. Applying Various Rules in Writing Formulas Write the formula of the compound (a) tetranitrogen tetrasulfide; (b) ammonium chromate; (c) calcium hypochlorite. Solution
(a) Molecules of this compound consist of four n atoms and four S atoms. The formula is N4S4. (b) Two ammonium ions (NH4+ )must be present for every chromate ion(CrO42). Place parentheses around NH4+ ,followed by the subscript 2.The formula is (NH4)2CrO4. (c) Here there are one Ca2+ and two ClO ions in a formula unit.This leads to the formula Ca(ClO)2. Some Compounds of Greater Complexity The same...
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This note was uploaded on 05/07/2010 for the course FIN 401 taught by Professor Chemistry during the Spring '10 term at Uni Potsdam.
- Spring '10