Nomenclature Summary: AP Chem
Positive ions (Cations, Metals): Use a Roman Numeral in the name if the metal has more than 1
possible oxidation state: Na+ = sodium ion, Fe+2 = Iron(II) ion
Negative ions (Anions, Non-metals): monoatomic (One atomed): change ending to –ide;
Cl– = chloride, As–3 = arsenide
Some common polyatomic ions : (-ate, ite, ide) (bi- prefix means “hydrogen,” not “two” )
Most common ion with oxygen = -ate ending,
1 less oxygen = –ite ending,
1 more oxygen = per- prefix
1 less oxygen than ite = hypo- prefix
–1 charge
C2H3O2–
CN–
Acetate
OH–
Hydroxide
IO3–
NO3–
NO2–
Iodate
HCO3–
Hydrogen carbonate (bicarbonate)
–3 charge
Cyanide
Nitrate
Nitrite
ClO4–
ClO3–
ClO2–
ClO–
Perchlorate
MnO4–
SCN–
Permanganate
PO4–3 Phosphate
Chlorate
Chlorite
Hypochlorite
Thiocyanate
+1 charge
–2 charge
CO3–2
Carbonate
CrO4–2
Chromate
Cr2O7–2
Dichromate
C2O4–2
Oxalate
SO4–2
Sulfate
SO3–2
Sulfite
O2-2
Peroxide
NH4+ Ammonium
Ionic compounds (start with a metal, end with non-metal or polyatomic ion):
Write the formula for the Ions, then “criss-cross” to balance the charges. Always write the
postive ion (metal) first!! To Name an Ionic compound : Name the Cation, then name the
Anion. Don’t use prefixes for the name:
NaNO3 = Sodium Nitrate
CuCl2 = Copper (II) Chloride
Molecular compounds: (Start with a non-metal)
Formula: PREFIXES in the name tell you how many of each element are present in the molecule.
DON’T criss-cross! DON’T reduce!
Name : Use PREFIXES to tell how many of each element are in the molecule. The more positive
element is written first, and the –ide ending is always used on the second element.
mono = 1
hepta = 7
di= 2
octa = 8
CO2 = Carbon dioxide
tri = 3
nona= 9
tetra = 4
deca= 10
penta = 5
dodeca = 12
hexa = 6
Cl2O7 = Dichlorine heptoxide : (only need “mono” for 2nd atom)
Hydrates: Compounds containing water as part of their crystal structure. A raised dot (•) is
used to show that water is loosely attached to the ionic compound. First name the ionic compound
(as above), then use a prefix to denote how many hydrate (water) molecules are present.
For example: FeSO4•7 H2O is Iron(II) sulfate heptahydrate
(heptahydrate = 7 waters)
Acids: (Start with H+) : Compounds that give off hydrogen ions when dissolved in water.
The name of the acid depends on the ending of the name of the anion the hydrogen is
combined with. Remember the acid naming disease: “Ate-ic Ite-ous”
1. Anion ends in -ate, change the ate to -ic
H2SO4 = sulfate ion = sulfuric acid
2. Anion ends in -ite, change the ite to -ous.
H2SO3 = sulfite ion = sulfurous acid
3. Anion ends in -ide, add the prefix hydro-, change the ide to -ic
HCl = chloride ion = hydrochloric acid
Organic Compounds (Carbon, H, O, N, etc.) : Molecular compounds made of Carbon,
Hydrogen and Oxygen are usually “organic” compounds and have a complicated system of names.
Prefixes indicate the number of Carbons in a straight Carbon–Hydrogen (Hydrocarbon, “R”) chain
meth = 1
eth = 2
prop = 3
but= 4
pent = 5
hex = 6
hept = 7
oct = 8
non= 9
dec= 10
dodec = 12
The ending of the name tells how many Hydrogens are in a hydrocarbon (all C’s and H’s):
all Single bonds =
Double bond =
Triple bond =
Alkane;
Alkene;
Alkyne;
prefix–”ane” =
prefix–”ene” =
prefix–”yne” =
C nH2n+2
C nH2n
C nH2n–2
ethane = C2H6
ethene = C2H4
ethyne = C2H2
For the Hydrocarbon, or “R” chain part of an organic compound
“R” chain or “group”:
prefix–”yl” =
C nH2n+1
methyl = CH3–
ethyl= C2H5–
A few other organic compounds: The ending indicates the type of compound
Alcohols: R–OH , prefix –”ol” or “R” alcohol : C3H7OH = propanol or propyl alcohol
Amines : R–NH2: prefix–”amine” or “R” amine: C2H5NH2 = ethamine or ethyl amine
Halogens: R–Cl, R–Br, etc: Halo–alkane or “R” halide: CH3Cl = chloromethane or methy chloride