SNC2D – Chemistry: Chemical Reactions
Ionic Compounds with Multivalent Metals
Most transition metals and some metals in group 14 (or IVA) are multivalent (they can form ions of
different valences, or ionic charge). For example, iron can form Fe2+ and Fe3+ ions, which are named “iron
(II)” and “iron (III)”. They can then form different compounds with a particular anion.
There are 2 systems of rules for naming compounds with multivalent metals: International (IUPAC) and
“Classical” (“ous-ic”).
International (IUPAC) System
Writing Formulas:
1. Use the regular crisscross method for writing formulas of ionic compounds. The metal is
written first, and then the non-metal.
2. For the metal, use the valence (or charge) given in brackets in the name.
Examples:
copper (II) nitride
tin (IV) oxide
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Writing Names:
1. From the formula, “back-cross” the subscripts – this will give you the charges.
2. Write the names of the elements in the same order as the formula (metal first, followed
by the non-metal with “ide” suffix)
3. Use Roman numerals in brackets following the metal to indicate the valence (charge).
Examples:
FeI2
Cu2O
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Classical System (“ous-ic”)
Writing Formulas:
1. Use the regular crisscross method for writing formulas of ionic compounds. The metal is
written first, and then the non-metal. Look for the Latin name and charges of the metal
in the table of multivalent metals.
2. If the metal has the suffix “ous”, use the lower valence (charge). If it has the suffix “ic”,
use the higher valence.
Examples:
Stannous fluoride
ferric sulfide
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Writing Names:
1. From the formula, “back-cross” the subscripts – this will give you the ionic charges.
2. Write the names of the elements in the same order as the formula (metal first, followed
by the non-metal with “ide” suffix)
3. For the metal name, use the Latin name, and add the suffix “ous” if the low valence was
used, or the suffic “ic” if the high valence was used.
Examples:
Cu3N2
SnS (* - small trick to this one)
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SNC2D – Chemistry: Chemical Reactions
Practice I. Write the correct chemical formulas for the following:
1. gold (III) sulfide
Metals with Multiple Ionic Charges (Multivalent Metals)
Au2S3
2. gold (I) oxide
Au2O
3. bismuth (V) carbide
Bi4C5
4. tin (IV) phosphide
Sn3P4
5. iron (II) bromide
Element
Name
Bismuth
Chromium
Copper
Gold
Iron
Lead
Manganese
Mercury
Nickel
Tin
Symbol
Bi
Cr
Cu
Au
Fe
Pb
Mn
Hg
Ni
Sn
Valence
Low
High
3
5
2
3
1
2
1
3
2
3
2
4
2
4
1
2
2
3
2
4
FeBr2
6. lead (IV) oxide
Pb2O4 → PbO2
7. stannous sulfide
Sn2S2 → SnS
8. cuprous nitride
Cu3N
9. auric sulfide
Au2S3
10. cupric nitride
Cu3N2
Practice II. Write 2 names for the following, using IUPAC and Classical (ous-ic) rules
1. SnF4
tin (IV) fluoride, stannic fluoride
2. FeS
iron (II) sulfide, ferrous sulfide
3. PbO2
lead (IV) oxide, plumbic oxide
4. Cu3N
copper (I) nitride, cuprous nitride
5. AuF3
gold (III) fluoride, auric fluoride
6. CuI
copper (I) iodide, cuprous iodide
Latin
Name
cuprum
aurum
ferrum
plumbum
stannum