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.

Some Helpful Links

Writing Formulas
Naming Compounds
Formula Quiz
Naming Quiz

Class Resources (Handouts)


ammonium ion    NH4+

cadmium ion    Cd2+

silver ion    Ag+

zinc ion    Zn2+


acetate ion    C2H3O2-

carbonate ion    CO32-

chlorate ion    ClO3-

chromate ion    CrO42-

cyanide ion    CN-

dichromate ion    Cr2O72-

hydroxide ion    OH-

manganate ion    MnO3-

nitrate ion    NO3-

oxalate ion    C2O42-

phosphate ion    PO43-

silicate ion    SiO32-

sulfate ion    SO42-

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 HCO31-  (carbonate ion is CO32-)
bisulfate ion (and hydrogen sulfate ion) is HSO41-

A prefix of “dihydrogen” indicates the addition of two hydrogen ions to the rest of the ion.
dihydrogen phosphate is H2PO41- (phosphate ion is PO43-)

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 SO42-             sulfite ion is SO32-
chlorate ion is ClO31-        chlorite ion is ClO21-

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 ClO31-    chlorite ion is ClO21-    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 ClO41-          chlorate ion is ClO31-
peroxide ion is O22-                 oxide ion is O2-
permanganate ion is MnO41-    manganate ion is MnO31-

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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