# How do you name compounds containing polyatomic ions?

May 4, 2014

Compounds containing polyatomic ions act as ionic compounds.
The name of the compound is the created by taking the name of the metal and then adding the name of the polyatomic ion.

There is no easy way around simply memorizing the polyatomic ions.

Some examples of this would be,

$M g {\left(O H\right)}_{2}$
The metal is Magnesium ($M {g}^{+} 2$) and the polyatomic ion is Hydroxide ($O {H}^{-} 1$)
Magnesium Hydroxide

$K C l {O}_{3}$
The metal is Potassium (${K}^{+} 1$) and the polyatomic ion is Chlorate($C l {O}_{3}^{-} 1$).
Potassium Chlorate

$C {a}_{3} {\left(P {O}_{4}\right)}_{2}$
The metal is Calcium ($C {a}^{+} 2$) and the polyatomic ion is Phosphate ($P {O}_{4}^{-} 3$).
Calcium Phosphate

Keep in mind that there is one common positive polyatomic ion Ammonium ($N {H}_{4}^{+} 1$).

$N {H}_{4} {C}_{2} {H}_{3} {O}_{2}$
The positive polyatomic is Ammonium ($N {H}_{4}^{+} 1$) and the negative polyatomic ion is Acetate (${C}_{2} {H}_{3} {O}_{2}^{-} 1$)
Ammonium Acetate