The nitrate ion #NO_3^(-1)# is composed of one nitrogen atoms and three oxygen atoms arranged with an imbalance of one extra electron.
The phosphate ion #PO_4^(-3)# is composed of one phosphate ion and four oxygen atoms arranges with an imbalance of three extra electrons.
Most polyatomic ions are negative with the main exceptions being #NH_4^(+1)# and #H_3O^(+1)#. The ammonium ion which is composed of one nitrogen and 4 hydrogen with an imbalance of one less electron. The hydronium ion is created when water takes on a dissociated #H^+# ion in an acid solution.
Monatomic ions are single atoms with a positive or negative charge like Calcium #Ca^(+2)# having two less electrons and Chloride #Cl^(-1)# having one more electron.
