Chemical Nomenclature

Ionic

Recognize ionic compounds because they:
a.  Are binary compounds that contain a metal and a non-metal.
b.  Contain polyatomic ions.
Use the periodic table to predict charges on some atoms with certainty.

1.  The metal (retains element name) or polyatomic cation is first.  If the metal is Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Ra, or Al the charge is never indicated.  The charge is known from the periodic table.

NaCl sodium chloride
NH4Br ammonium bromide
2.  Followed by the name of the nonmetal with an -ide ending added or the polyatomic anion.
KCl potassium chloride
Ca(NO3)2 calcium nitrate
3.  If the metal has more than one possible charge, indicate the charge using roman numerals (and no space):
FeCl2 iron(II) chloride
CuSO4 copper(II) sufate
An incorrect, but still frequently seen, method uses the Latin root and an added -ous for the lower charge or -ic for the higher charge. (Fe(ClO3)2, ferrous chlorate; Fe(ClO2)3, ferric chlorite).  Do not use this method.

Polyatomic Ions.

1.  Cations.
Formula Name
NH4+ ammonium ion
Hg22+ mercury(I)

2.  Anions.

a.  Only a few polyatomic anions have an -ide ending.
Formula Name
CN- cyanide
OH- hydroxide
O22- peroxide
O2- superoxide
N3- azide
b.  Oxyanions.  -ate more oxygen, -ite less oxygen
Formula Name
NO2- nitrite
NO3- nitrate
SO32- sulfite
SO42- sulfate
PO33- phosphite
PO43- phosphate
c.  Sometimes oxyanions have an extra hydrogen
Formula Name
SO42- sulfate
HSO4- hydrogen sulfate (or bisulfate)
SO32- sulfite
HSO3- hydrogen sulfite (or bisulfite)
PO43- phosphate (tribasic)
HPO42- hydrogen phosphate (dibasic)
H2PO4- dihydrogen phosphate (monobasic)
d.  Sometimes there are more than two ions, sometimes only one
Formula Name
ClO- hypochlorite
ClO2- chlorite
ClO3- chlorate
ClO4- perchlorate
CO32- carbonate
HCO3- hydrogen carbonate ( or bicarbonate)
C2H3O2- acetate
Formula Name
MnO4- permanganate
CrO42- chromate
Cr2O72- dichromate

Examples

Compound Name
FeS iron(II) sulfide
Fe2O3 iron(III) oxide
Hg2Br2 mercury(I) bromide
Hg(N3)2 mercury(II) azide
CuI copper(I) iodide
Cu(ClO4)2 copper(II) perchlorate
SnF2 tin(II) fluoride
SnCl4 tin(IV) chloride

Molecular

Recognize molecular compound because they are binary and contain only non-metals.

1.  Start with element to the left side (most metallic) on the periodic table followed by the second element with an added -ide (as if it were an anion) as a suffix.

2.  Always use Greek prefixes to indicate the number of each type of atom in the compound:

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

 
CO carbon monoxide
CO2 carbon dioxide
N2O5 dinitrogen pentoxide

Do not use mono for the first element.  In some cases, drop adjacent vowels caused by a prefix.

Formula Name
NO nitrogen monoxide
N2O dinitrogen monoxide
NO2 nitrogen dioxide
N2O5 dinitrogen pentoxide
N2O3 dinitrogen trioxide
CI4 carbon tetraiodide
S2Cl2 disulfur dichloride

Acids

1.  Hydro acids: hydro + halogen name + ic
 
Formula Name
HCl  hydrochloric acid
HF hydrofluoric acid

2.  Oxoacids: polyatomic ion + acid.  Recognize as polyatomic ions with a hydrogen at the beginning of the formula.  Name with -ous (replacing -ite and -ic replacing -ate suffix)
 

Formula Name Source
HNO3 nitric acid nitric from nitrate
HNO2 nitrous acid nitrous from nitrite
H2SO4 sufuric acid sufuric from sulfate
H2SO3 sufurous acid sufurous from sulfite