1. Binary Ionic Compounds
Consist of only two elements
Name the positive ion (Cation)
Name the negative ion (Anion), changing the ending to –ide
When metals that can form more than one type of ion are in a compound, use Roman Numerals in parentheses after the name of the metal to show charge.
Transition Metals
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2. Examples:
NaCl sodium chloride MgO magnesium oxide Cu2S copper (I) sulfide SnCl4 tin (IV) chloride
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3. Ternary Ionic Compounds
Made up of three elements
Name the cation then name the polyatomic ion without changing the ending to “ide”
Examples:
Na2SO4
sodium sulfate
FeCrO4
iron (II) chromate
Hint: Iron is a transition metal and has more than one ionic charge.
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4. Rule of Thumb If the first element is a metal, use ionic nomenclature.
If all elements are non-metals, use the molecular namenclature.
Watch for NH4+1, cation polyatomic ion.
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5. Naming Molecular Compounds
The elements are named in the order they appear in the formula.
Prefixes are used to denote the number of atoms each element in the molecule. An exception is that the first element named is given a prefix only if there is more than one atom of the element in the molecule.
The ‘o’ or ’a’ at the end of the prefix is dropped when the word following the prefix begins with a vowel.
The last element’s ending is changed to –ide.
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6. Examples:
ICl3 iodine trichloride As2O5 diarsenic pentoxide C4H10 butane C2H4 ethene
Alkane: CnH2n+2
Alkene: CnH2n
Alkyne: CnH2n-2
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