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 Some Transition Metals can form more than one type of cation. For example, copper can have either a +1 or a +2 charge  Iron can have either a +2 or a +3 charge. (see periodic table)  The charge of an ion is also called the “combining capacity” or “valence” of the element.

 The charge of the metal in a compound is noted in the name with a matching Roman Numeral:  +1 = (I)  +2 = (II)  +3 = (III)  This is called the STOCK system for naming compounds.

 Charge on Copper ion = +1 or +2  Since the Roman Numeral shown is (I), the charge to use is +1  Charge on Sulfur ion = -2  Cu S   Criss Crossing gives the formula Cu 2 S

 The Roman Numeral (II) means to use the charge of +2 for Copper  The charge for Sulfur is -2  Cu S   Equal ratio of charges means the formula is CuS

1. Copper (I) Oxide 1.Cu 2 O 2. Lead (IV) Bromide 1.PbBr 4 3. Iron (III) Sulfide 1.Fe 2 S 3 4. Nickel (II) Fluoride 1.NiF 2 5. Manganese (IV) Sulfide 1.Mn 2 S 4 MnS 2 (must reduce to lowest terms)

 Fe Cl 3 (Iron can have a charge of either +2 or +3)  Cl has a charge of -1  Fe Cl 3  ____ - 3 (-1 x 3 = -3)  The charge on Fe must balance with charge on Cl  Since there is One Fe, the charge on it must be +3  So the iron used is the Fe+3 ion, so use the Roman Numeral (III) in the name:  The name is Iron (III) Chloride

 Cu = +1 or +2  S = -2  Cu 2 S  _____ - 2  Since there are 2x Cu, and since the overall charge must = +2, the charge on one Cu must be +1  The name is Copper (I) Sulfide

 Note:  Change #1 (h) to Nickle (II) Chloride  Change #2 (f) to BeF 2

 1. Iron (III) Oxide  2. Lead (IV) Oxide  3. Nickel (II) Chloride  4. Chromium (III) Nitride  5. Mercury (II) Oxide

(II)

BeF 2