Sept 27/28
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SNC2D - Chemistry
Ionic Compounds with Multivalent Metals
Most transition metals and some metals in group 14 (or IVA) are multivalent (they have more than one
possible valence). They can form different numbers of bonds depending on the conditions.
There are 2 systems of rules for naming compounds with metals of variable valence: IUPAC
(international) and “Classical” (“ous-ic”).
International System
Writing
Formulas:
1. Use the regular methods for writing formulas of ionic compounds (ionic
charge or criss-cross). The metal is written first, and then the non-metal.
2. For the metal, use the charge given in brackets.
Examples:
copper (II) nitride
Writing Names:
tin (IV) oxide
1. From the formula, “back-cross” the subscripts – this will give you the
valences.
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 charge.
Examples:
FeI2
SnO
Classical System (“ous-ic”)
Writing
Formulas:
1. Use the regular methods for writing formulas of ionic compounds (ionic
charge or cross-over). The metal is written first, and then the non-metal.
2. If the metal has the suffix “ous”, use the lower valence. If it has the suffix “ic”,
use the higher valence. See the handout with the list of elements with
variable valences
Examples:
Cuprous fluoride
Writing Names:
ferric sulfide
1. From the formula, “back-cross” the subscripts – this will give you the
valences.
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.
Sept 27/28
Examples:
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Cu3N2
Practice I. Write the correct formulas for the
following:
SNC2D - Chemistry
SnS
8. gold (I) sulfide
1. cobalt (II) sulfide
9. tin (IV) carbide
2. chromium (III) bromide
10. copper (II) nitride
3. lead (II) oxide
11. tin (IV) iodide
4. gold (I) oxide
12. copper (I) oxide
5. tin (II) sulfide
13. lead (III) phosphide
6. iron (III) nitride
14. Manganese (IV) oxide
7. bismuth (V) carbide
15. Nickel (III) sulfide
Practice II. Write 2 names for the following,
using IUPAC rules
1. SnF4
2. FeS
3. PbO2
4. HgCl
5. Ni2O3
6. Cu3N
7. AuF3
8. CuI
9. PbCl4
10. CuCl2
11. CoF3
12. FeO
13. MnCl7