South Pasadena • Chemistry
Name
Period
Date
4 · Salts and Solutions
FORMING IONIC COMPOUNDS
An ionic compound is formed when a cation (positive ion) is bonded to an anion (negative ion). The positive and
negative charges need to cancel to form a neutral compound.
If more than one ion is needed to cancel out the charges, we use a subscript. For example, when combining Ca 2+
and Cl–, we need one Ca2+ and two Cl– ions, so the formula is CaCl2. Finally, we can name the compound simply
by writing the name of the positive ion and the name of the negative ion.
If we need more than one of a polyatomic ion, then we need to write subscript outside of parentheses.
Formula of Formula # of Cation # of Anion
Cation
of Anion
Needed
Needed
Formula for Ionic
Compound
Name of Ionic Compound
Ca2+
Cl–
1
2
CaCl2
Calcium chloride
Ca2+
NO3–
1
2
Ca(NO3)2
Calcium nitrate
Na+
Cl–
1
1
NaCl
Sodium chloride
Na+
O2–
2
1
Na2O
Sodium oxide
Na+
NO3–
1
1
NaNO3
Sodium nitrate
Na+
SO42–
2
1
Na2SO4
Sodium sulfate
Na+
PO43–
3
1
Na3PO4
Sodium phosphate
NH4+
Cl–
1
1
NH4Cl
Ammonium chloride
NH4+
O2–
2
1
(NH4)2O
Ammonium oxide
NH4+
NO3–
1
1
NH4NO3
Ammonium nitrate
NH4+
SO42–
2
1
(NH4)2SO4
Ammonium sulfate
NH4+
PO43–
3
1
(NH4)3PO4
Ammonium phosphate
Formula of Formula # of Cation # of Anion
Cation
of Anion
Needed
Needed
Formula for Ionic
Compound
Name of Ionic Compound
Ca2+
Cl–
1
2
CaCl2
Calcium chloride
Ca2+
O2–
1
1
CaO
Calcium oxide
Ca2+
NO3–
1
2
Ca(NO3)2
Calcium nitrate
Ca2+
SO42–
1
1
CaSO4
Calcium sulfate
Ca2+
PO43–
3
2
Ca3(PO4)2
Calcium phosphate
Al3+
Cl–
1
3
AlCl3
Aluminum chloride
Al3+
O2–
2
3
Al2O3
Aluminum oxide
Al3+
NO3–
1
3
Al(NO3)3
Aluminum nitrate
Al3+
SO42–
2
3
Al2(SO4)3
Aluminum sulfate
Al3+
PO43–
1
1
AlPO4
Aluminum phosphate
Sn4+
Cl–
1
4
SnCl4
Tin(IV) chloride, or stannic chloride
Sn4+
O2–
1
2
SnO2
Tin(IV) oxide, or stannic oxide
Sn4+
NO3–
1
4
Sn(NO3)4
Tin(IV) nitrate, or stannic nitrate
Sn4+
SO42–
1
2
Sn(SO4)2
Tin(IV) sulfate, or stannic sulfate
Sn4+
PO43–
3
4
Sn3(PO4)4
Tin(IV) phosphate, or
stannic phosphate