Unit V Chemical Nomenclature
1. Be able to write formulas for binary and polyatomic ionic compounds (including the stock system).
2. Be able to write names for binary and polyatomic ionic compounds (including the stock system).
3. Be able to write formulas and name binary covalent compounds.
4. The student must be able to do this with at least a 90% accuracy before moving on to the next unit.

Suggested Problems: Do what you need -you will have many worksheets and access to computer programs for practice.

Binary Formula Summary

1.    Positive ion is written first.
    a. If both elements are nonmetals, the one with the lower electronegativity is treated as the cation.

2.    The anions get their names changed to end in “ide”.

3.    For ionic bonds metals lose valence electrons and nonmetals gain electrons until they satisfy the octet rule. When combined, the sum of the oxidation numbers must be equal to zero.

4.    For covalent bonds two nonmetals share electrons until they satisfy the octet rule.

5.    When more than one compound can be formed between the two nonmetals (two nonmetals where neither is hydrogen) prefixes are used in the name to indicate the number of atoms except that “mono” is never used on the first atom.

Prefixes    mono=1    di=2        tri=3        tetra=4    penta=5
            hexa=6    hepta=7    octa=8    nona=9    deca=10

6.    Diatomic Elements: There are 8 elements that exist as two atoms of the same element joined in a covalent molecule. [hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, iodine, astatine]

a.    Rule of 7’s+1 “There are 7 elements, starting with element number 7, using group 7 (or 17 on the new numbering system), forming the figure “7” on the periodic chart plus element number 1 (hydrogen)

b.    All of the elements that end in “gen” or “ine”

Systematic Naming For Polyatomic Anions
and Transition Metal Cations

Prefixes of “hydrogen” or “bi”
A prefix of hydrogen or bi indicates the addition of one hydrogen ion (H⁺) to the rest of the ion.
bicarbonate ion (and hydrogen carbonate ion) is HCO₃^1- (carbonate ion is CO₃^2-)
bisulfate ion (and hydrogen sulfate ion) is HSO₄^1-

A prefix of “dihydrogen” indicates the addition of two hydrogen ions to the rest of the ion.
dihydrogen phosphate is H₂PO₄^1- (phosphate ion is PO₄^3-)

Changing the “ate” ending to “ite” or adding prefixes of “hypo” or “per”.
Changing ate to ite reduces the number of oxygens in the polyatomic ion by one. The charge remains the same.
sulfate ion is SO₄^2-             sulfite ion is SO₃^2-
chlorate ion is ClO₃^1-        chlorite ion is ClO₂^1-

Adding hypo to the “ite” ending means one less oxygen than the “ite” ending (or two less than the “ate” ending). The charge remains the same.
chlorate ion is ClO₃^1-    chlorite ion is ClO₂^1-    hypochlorite ion is ClO^-

Adding per to the “ate” ending means one more oxygen than the “ate ending. The charge remains the same.
perchlorate ion is ClO₄^1-         chlorate ion is ClO₃^1-
peroxide ion is O₂^2-           oxide ion is O^2-
permanganate ion is MnO₄^1- manganate ion is MnO₃^1-

Elements of the transition metals and the metals to the right of the transition metals often have more than one possible oxidation number. The oxidation number is written as a Roman numeral in the name. This system is called the Stock naming system. The classical naming system uses endings of “ous” and “ic”. You will not be required to learn the classical naming system. Exceptions to this are silver, cadmium, and zinc ions.

iron (III) ion is Fe³⁺        iron (II) ion is Fe²⁺

lead (II) ion is Pb²⁺           lead (IV) ion is Pb⁴⁺

antimony (III) ion is Sb³⁺    antimony (V) ion is Sb⁵⁺

mercury (II) ion is Hg²⁺            mercury (I) ion is Hg₂²⁺

zinc ion is Zn²⁺               cadmium ion is Cd²⁺       silver ion is Ag¹⁺

The sum of the charges for all compounds must be zero!!!

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The sum of the charges for all compounds must be zero!!!