Naming Compounds

Naming a compound and writing its corresponding formula allow the scientific community to know exactly what substance is being talked about and to write chemical equations using the same set of rules. These rules are broken down into 4 categories which are described below. You will also need to memorize a few other compounds which are listed at the end of this handout

Naming Compounds

Type 1 – Metals in group 1, 2, or 13 plus a nonmetal

1) name the ions

a) name the metal element

b) give the nonmetal prefix and add “ide”

c) it doesn’t matter how many of each ion you have (don’t use “di” for “2” etc.)

Type 2 – Metal NOT in group 1,2 or 13 plus a nonmetal

1) Find the total charge on all anions in the compound

2) Balance this charge with the same positive charge on all cations such that the compound is neutral

3) Determine the charge on EACH cation

4) Name the cation followed by a Roman numeral that shows the charge on EACH cation

5) Name the anion

Type 3 – Two nonmetals bonded together (ions are not present)

1) Name the first element as if it were a cation

2) Name the second element as if it were an anion

3) Add prefixes to each cation name and anion name to show the number of each atom in the compound

4) We never use the prefix “mono” for the first element

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

Ex. CO₂ would be Carbon Dioxide. P₂O₃ would be Diphosphorus Trioxide

Polyatomic Ions

Polyatomic Ions are ions that contain a number of atoms. There is a list of polyatomic ions below. There is no formula for learning how to write their names, you must commit them to memory. (When you commit them to memory, remember the charges, names, and formulas.) Naming Polyatomic compounds is much like naming Binary I or II compounds. Remember transition metals usually can form two or more ions and and a Roman numeral should be used to show the charge on each cation in the compound.

Common Polyatomic Ions
Ion	Name	Ion	Name
NH4^+	Ammonium	O2^-2	Peroxide
NO2^-	Nitrite	CrO4^-2	Chromate
NO3^-	Nitrate	Cr2O7^-2	Dichromate
SO3^-2	Sulfite	MnO4^-	Permanganate
SO4^-2	Sulfate	C2H3O2^-	Acetate
HSO4^-	Hydrogen Sulfate	ClO4^-	Perchlorate
OH^-	Hydroxide	ClO3^-	Chlorate
CN^-	Cyanide	ClO2^-	Chlorite
PO4^-3	Phosphate	ClO^-	Hypochlorite
HPO4^-2	Hydrogen Phosphate	HCO3^-	Hydrogen Carbonate
H2PO4^-	Dihydrogen Phosphate	CO3^-2	Carbonate

You should memorize the bold polyatomic ions above.

Compounds That You Should Know By Memory

1. HCl (Hydrochloric Acid)
2. H₂SO₄ (Sulfuric Acid)
3. HNO₃ (Nitric Acid)
4. HC₂H₃O₂ (Acetic Acid)
5. NH₃ (Ammonia)