3-5 Naming Ionic Compounds ~ Type/Class 2 Rules (Section 5.2) And you!

Metals in the middle of the periodic table, so called “transition” metals, can have more than one charge (oxidation state). We need a different set of rules for naming ionic bonds between these metals and nonmetals. So we can know what the charge is on the transition metal cation!

The following Class 2 rules apply to ionic bonds, in particular, a transition metal + nonmetal. Names (from formulas): Metal cation (+) first, then the charge on the metal in roman numerals inside parentheses, and lastly the nonmetal anion (-) with “ide” ending.

CoBr 2 = (unknown chg. on Co ion) Co ?+ + 2 Br – ? + charges = 0 ????? 2 + !!!!! Therefore the Co ion must have a 2 + charge Co Br - = Cobalt (II) bromide !the (II) is the charge on the Co ion (not the # of Br ions!!!)

CoBr 3 Co ?+ + 3 Br - = 0 ? Co Br - = Cobalt (III) bromide

? PbO, PbO 2 ? PbO = Pb ?+ + O -2 = Pb 2+ + O -2 = Lead (II) oxide PbO 2 = Pb ?+ + 2 O -2 = Pb O -2 = Lead (IV) oxide Cr 2 (SO 4 ) 3 Chromium (III) sulfate WOW!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Formulas (from names) Write the metal with charge (from roman numeral) and nonmetal with charge. Balance charges. Sum of charges for an ionic compound must = zero!

Iron(II) oxide Fe +2 + O -2 = FeO Iron(III) oxide = Fe +3 + O -2 = Fe 2 O 3 Manganese(II) sulfate = Mn +2 + SO 4 -2 = MnSO 4

Lead(IV) phosphate = Pb +4 + PO 4 -3 = Pb 3 (PO 4 ) 4 Copper(II) permanganate = Cu +2 + MnO 4 -1 = Cu(MnO 4 ) 2 Iron(III) nitride = Fe +3 + N -3 = FeN Iron(III) nitrite = Fe +3 + NO 2 -1 = Fe(NO 2 ) 3

And finally Iron(III) nitrate = Fe +3 + NO 3 -1 = Fe(NO 3 ) 3 WELL DONE!!!!!!!

ALERT!!!! N -3, NO 2 -1, NO 3 -1, N Nitride, Nitrite, Nitrate, Nitrogen S -2, SO 3 -2, SO 4 -2, S Sulfide, Sulfite, Sulfate, Sulfur