FORMULA NAMING RULES
I. IONIC COMPOUNDS - SALTS
NEVER have to indicate how many of each ion. Only one combination is possible to obtain neutral formula unit.
A. BINARY SALTS - A metal (or NH4+) is bonded to a simple non-metal
Naming rule
1. Name the metal
2. Drop ending of non-metal and replace with “ide”
Examples: NaCl is sodium chloride. K2S is potassium sulfide.
NH4Br is Ammonium bromide.
B. TERNARY SALTS – A metal (or NH4+) is bonded to a polyatomic ion.
Naming rule
1. Name the metal
2. Name the polyatomic ion
Examples: CaCO3 is calcium carbonate. Na3PO4 is sodium phosphate.
C. SALTS CONTAINING METALS WITH MORE THAN ONE POSSIBLE CHARGE
1. Roman Numeral Method – Place a roman numeral after the name of the metal to
Indicate the actual charge.
Examples: Cu2+ is copper (II). CuCl2 is copper (II) chloride.
Sn4+ is tin (IV). Sn(ClO2)4 is Tin (IV) chlorite.
2. Classical Naming Method - Add “ous” to name of metal if charge is the lower of the two possible charges. Add “ic” to name of metal if charge is the higher of the two possible charges.
USE LATIN STEMS for the metals Cu, Pb, Fe and Sn.
Examples: cuprous(Cu1+), cupric (Cu2+) plumbous(Pb2+), plumbic(Pb4+)
ferrous (Fe2+), ferric (Fe3+) stannous (Sn2+), stannic (Sn4+)
CuCl2 is cupric chloride Sn(ClO2)4 is stannic chlorite
II. MOLECULAR COMPOUNDS - Contain non-metals COVALENTLY bonded.
ALWAYS have to indicate the number of each atom. Many possible combinations exist.
We will only name BINARY molecules. Two different kinds of atoms.
A. Naming Rules
1, Use prefixes to indicate the number of each type of atom
1 mono 4 tetra 7 hepta 10 deca
2 di 5 penta 8 octa
3 tri 6 hexa 9 nona
2. If there is only one of the “first” element, omit mono.
3. Replace ending of second element name with “ide” to indicate binary.
B. Examples: N20 dinitrogen monoxide
CO2 carbon dioxide
P2O5 diphorous pentoxide
III. HYDRATED SALTS – Binary or ternary salts loosely bonded to a specific number of water
molecules
A. Naming Rules
1. Name the salt by “Ionic Compounds” Rules
2. Add numerical prefix and word “hydrate” to indicate number of water molecules.
Prefixes are the same as those given under “molecular compounds”.
B. Examples: BaCl2 ● 2H2O Barium chloride dihydrate
CuSO4 ● 5H2O Cupric sulfate pentahydrate or
Copper (II) pentahydrate.
IV. ACIDS – Compounds with formulas that begin with the element “hydrogen”
A. Naming rules
1. Binary acids – Acids which do NOT contain oxygen
a. Use prefix “hydro”
b. Write stem (beginning) of the non-metal name
c. Add suffix “ic”
d. End with the word “Acid”
Examples: HCl “hydro” + “chlor” + “ic” = hydrochloric acid
HI “hydro” + “iod” + “ic” = hydroiodic acid
HCN “hydro” + “cyan” + “ic” = hydrocyanic acid
2. Ternary acids – Acids which contain oxygen
a. No “hydro” prefix used
b. If polyatomic ion name ends in “ate”, the name of the acid ends in “ic”.
c. If polyatomic ion name ends in “ite”, the name of the acid ends in “ous”.
d. End with the word “Acid”
Examples: H2SO4 Sulfuric acid
H2SO3 Sulfurous acid
H3PO4 Phosphoric acid
H3PO3 Phosphorous acid