Section 2.8 Naming Inorganic Compounds Chemical Nomenclature Naming system of substances Latin: ◦ Nomen~ name Calare~ to call Two main categories: ◦ Organic and Inorganic Inorganic Compound Rules Ionic Acids Molecular Ionic Compounds Compounds Anions Cations Ionic Compounds 1. Cations ◦ a) Same name as the metal they formed from: Na+ sodium ion ◦ b) Metals forming different cations: use Roman numerals in parentheses: Fe2+ iron (II) ion Fe 3+ iron (III) ion ~ Older method: -ous or –ic ending Fe2+ ferrous ion Fe3+ ferric ion Ionic Compounds c) Cations formed from nonmetal atoms have names that end in –ium NH4+ ammonium ion H3O+ hydronium ion Ionic Compounds 2. Anions ◦ a) Monoatomic anions are formed by replacing ending of name of element with –ide O2- oxide N3- nitride ◦ b) Polyatomic anions contain oxygen (oxyanions) end in –ate or –ite NO3- nitrate NO2- nitrite Ionic Compounds ◦ b) Polyatomic anions contain oxygen (oxyanions) end in –ate or –ite ◦ -ite has one fewer O atoms than an –ate NO3- nitrate NO2- nitrite ◦ Prefixes per- and –hypo are used when there are more than four members ClO4 ClO3 ClO2 ClO- perchlorate chlorate chlorite hypochlorite Ionic Compounds c) Anions derived from adding H+ to an oxyanion: begin with either hydrogen or dihydrogen CO32 HCO3- carbonate hydrogen carbonate PO43 H2PO43- phosphate dihydrogen phosphate Ionic Compounds 3. Compounds ◦ Names consist of the cation name followed by the anion name CaCl2 AlPO3 CuSO4 calcium chloride aluminum phosphite copper (II) sulfate Acids -ides -ates /-ites Acids 1. With anions ending in –ide: change –ide to –ic, add the prefix hydro-, and follow with the word acid Anion Corresponding Acid Cl- (chloride) HCl (hydrochloric acid) S2- (sulfide) H2S (hydrosulfuric acid Acids 2. With anions ending in –ate or –ite: ◦ Change –ate to –ic ◦ Change –ite to –ous ◦ Add the word acid Anion Corresponding Acid ClO4- (perchlorate) HClO4 (perchloric acid) ClO3- (chlorate) HClO3 (chloric acid) ClO2- (chlorite) HClO2 (chlorous acid) ClO- (hypochlorite) HClO (hypochorous acid) Molecular Compounds (Binary) 1. Name the element farther to the left in the periodic table first. 2. If both in same group, the one with the higher atomic number is named first. 3. Name the second with an –ide ending 4. Greek prefixes are used to indicate number of atoms of each element