Anions (negative ions) Monoatomic Oxyanions (containing oxygen) Others and Exceptions Oxyanions which contain hydrogen Rule: Stem of the element name + "ide" Rule: least oxygen less oxygen more oxygen most oxygen Rule: These items do not follow any rules; they must be memorized. The rules referred to are those in the box just to the left. Rule: H plus oxyanion: "hydrogen" + name of oxyanion Examples: H¯ hydride ion F¯ fluoride ion 2 O ¯ oxide ion 3 N ¯ nitride ion C 4¯ carbide ion Examples: ClO¯ ClO2¯ ClO3¯ ClO4¯ SO32¯ SO42¯ hypo ___ ite ion ___ ite ion ___ ate ion per ___ ate ion hypochlorite ion chlorite ion chlorate ion perchlorate ion sulfite ion sulfate ion Comment: Halogens (except F) form all four ions. When only two of the four exist, they are the -ite and -ate ions. Examples: OH¯ CN¯ SCN¯ OCN¯ O22¯ O2¯ MnO42¯ MnO 4¯ C2H3O2¯ Cr2O72¯ C2O42¯ hydroxide ion cyanide ion thiocyanate ion cyanate ion peroxide ion superoxide ion manganate ion permanganate ion acetate ion dicromate ion oxalate ion H2 plus oxyanion: "dihydrogen" + name of oxyanion Examples: HCO3¯ hydrogen carbonate ion or bicarbonate ion HSO4¯ hydrogen sulfate ion or bisulfate ion HPO42¯ hydrogen phosphate ion or biphosphate ion H2PO4¯ dihydrogen phosphate ion Comment: H2CO3 is not named using this rule because it is a compound see comment just to and not an ion. the left.