Soluble molecules are aqueous (dissociate) in water.

Soluble Ions:                    Except when combined with:

NH4+ - ammonium

no exceptions

Li+ - lithium

no exceptions

Na+ - sodium

no exceptions

K+ - potassium

no exceptions

Rb+ - rubidium

no exceptions

Cs+ - cesium

no exceptions

NO3- - nitrates

no exceptions

ClO3- - chlorates

no exceptions

ClO4- - perchlorates

no exceptions

C2H3O2- - acetates

no exceptions

Cl- - chlorides

Ag1+, Hg22+, Pb2+

Br- - bromides

Ag1+, Hg22+, Pb2+

I- - iodides

Ag1+, Hg22+, Pb2+

SO42- - sulfates

Ca2+, Sr2+, Ba2+, Pb2+


Insoluble molecules stay solid in water.

Insoluble Ions                Except when combined with:

PO43- - phosphates

NH4+, (Group 1A Metals): Li+, Na+, K+, Rb+, Cs+

CO32- - carbonates

NH4+, (Group 1A Metals): Li+, Na+, K+, Rb+, Cs+

C2O42- - oxalates

NH4+, (Group 1A Metals): Li+, Na+, K+, Rb+, Cs+

O2- - oxides

(Group 1A Metals): Li+, Na+, K+, Rb+, Cs+

OH- - hydroxides

NH4+, (Group 1A Metals): Li+, Na+, K+, Rb+, Cs+

and Ca2+, Sr2+, Ba2+

S2- - sulfides

NH4+, (Group 1A Metals): Li+, Na+, K+, Rb+, Cs+ 

The following make “sparingly soluble” compounds with sulfides

(Group 2A): Be2+,Mg2+,Ca2+,Sr2+,Ba2+