Name ______________________________________________ Date _____________________ Period______
Writing Formulas and Naming Ionic Compounds, Covalent Compounds and Acids
IONIC COMPOUNDS:
Ionic compouds start with a metal or ammonium (cation +)
Steps for writing FORMULAS for ionic (metal + non-metal) compounds:
1. Write the METAL (cation) or ammonium (cation) first and the NON-METAL (anion) second.
2. Write the CHARGE for each ion.
3. Cross the charges to become subscripts on the opposite ion. If you must add a subscript after a
polyatomic ion, it must be placed in parentheses and then the subscript is added outside the
parentheses.
Ex: Aluminum nitrate
Al+3 (NO3)-1
Ex: Tin (IV) sulfate
Sn+4 (SO4)-2 =
= Al(NO3)3
Sn2(SO4)4 = Sn(SO4)2
Must Reduce
Steps for NAMING ionic compounds
1. Write the name of the metal (cation) or ammonium. If the cation is NOT group 1, 2, Ag, Zn, Cd, or
Al, USE roman numerals to indicate its charge.
2. Shorten the name of the non-metal (monatomic anion) and add the suffix "ide". If the anion is a
polyatomic ion, simply write the name of the polyatomic ion.
Ex: CaBr2 = Calcium bromide
Ex: Pb(SO4)2 = Lead (IV) sulfate
Calcium is in group 2.
Do not indicate its charge in the name.
Lead is considered an “other metal.”
Must indicate its charge in the name.
Determine its charge from the anion.
COVALENT (MOLECULAR) COMPOUNDS:
Covalent compounds start with a non-metal.
Steps for writing FORMULAS for covalent (non-metal + non-metal) compounds:
1. Use the following prefixes to indicate the number of atoms of each element present in a covalent
(molecular) compound.
Number
1
2
3
4
5
3
Example:
Prefix
Mono
Di
Tri
Tetra
Penta
Number
6
7
8
9
10
Prefix
Hexa
Hepta
Octa
Nona
Deca
5
TRInitrogen PENToxide = N3O5
Steps for NAMING covalent (non-metal + non-metal) compounds:
1. Use the prefixes above to indicate the number of atoms of each element present in a covalent
(molecular) compound. Exception – Never use mono with the first element. Change the ending on
the second non-metal to “-ide.”
Examples:
N2Br4 = DInitrogen TETRAbromide
CO2 = Carbon DIoxide
ACIDS:
Acids start with hydrogen.
Steps for writing FORMULAS for acids:
1. Binary Acids (hydrogen and a non-metal)
a. Name begins with “hydro”
i. Write the cation (always H+1 for acids). Write the anion.
ii. Cross the charges to become subscripts on the opposite ion.
Example: Hydrobromic Acid =
H+1 Br-1 = H+1 Br-1
HBr
=
2. Ternary Acids (hydrogen and a polyatomic ion)
a. Name DOES NOT begin with “hydro”
i. Write the cation (always H+1 for acids).
ii. Write the anion. Determine the polyatomic ion from the name of the acid. If it is
______ic Acid, then the polyatomic ion name ends in _____ate. If it is _____ous Acid,
then the polyatomic ion name ends in _____ite.
iii. Cross the charges to become subscripts on the opposite ion.
Example: Chromic Acid =
H+1 CrO4-2 = H+1 CrO4-2
=
H2CrO4
Name does not begin with “hydro” so it
contains a polyatomic ion. Since the
acid name ends with –ic, the
polyatomic ion name ends with –ate
(chromate).
Example: Nitrous Acid =
H+1 NO2-1 = H+1 NO2-1
=
HNO2
Name does not begin with “hydro” so it
contains a polyatomic ion. Since the
acid name ends with –ous, the
polyatomic ion name ends with –ite
(nitrite).
Steps for NAMING acids:
1. Binary Acids (hydrogen and a non-metal)
a. Anion name ends in
–ide, change to hydro________ic Acid.
Example: HCl = Hydrochloric Acid
Chloride
2. Ternary Acids (hydrogen and a polyatomic ion)
a. Anion name ends in
–ate, change to _____ic Acid
–ite, change to _____ous Acid
Example: HClO3 = Chloric Acid
Chlorate
Example: HClO2 = Chlorous Acid
Chlorite
Write the formulas for the following compounds:
Cation
Anion
a. Potassium acetate
_______
_______
___________________
b. Hypochlorous acid
_______
_______
___________________
c. Nitrogen heptabromide
Formula
___________________
d. Lithium phosphate
_______
_______
___________________
e. Carbonic acid
_______
_______
___________________
f. Lead (IV) dichromate
_______
_______
___________________
g. Carbon monoxide
___________________
h. Zinc permanganate
_______
_______
___________________
i. Copper (II) nitrite
_______
_______
___________________
j. Silver chlorate
_______
_______
___________________
k. Dinitrogen pentoxide
___________________
l. Hydrochloric acid
_______
_______
___________________
m. Calcium Hydroxide
_______
_______
___________________
n. Manganese (III) Chloride
_______
_______
___________________
o. Strontium nitride
_______
_______
___________________
Name the following compounds:
a. SO2
___________________________________
b. Hg(NO3)2 ___________________________________
c. (NH4)2S
___________________________________
d. K2O
___________________________________
e. HClO2
___________________________________
f. SiO2
__________________________________
g. Pb(CrO4)2 ___________________________________
h. Al(NO3)3 ___________________________________