NaCl, ZnCl, CuF2, NaOH, KOH, K2Cr2O7
NaCl, CaCO3, Mg(NO3)2, KF, RB2O, FrBR
caesium chloride, CsCI
magnesium nitride, Mg3N
NaCl sodium chloride
NaI Sodium iodide
NaBr sodium bromide
KCl Potassium chloride
KI potassium iodide
KBr potassium bromide
There are many ionic compounds. but for such an open question you can take any combination of a group 1 element and combine it with any group 7
I. Compounds of great ionic character
potassium ion + iodide ion = potassium iodide
cobalt(II) ion + two chloride ions = cobalt(II) chloride
ion + three chloride ions = cobalt(III) chloride
mercury(I) ion + two chloride ions = mercury(I) chloride or mercurous chloride
silver ion + nitrate ion = silver nitrate
two ammonium ions + sulfide ion = ammonium sulfide
aluminum ion + bicarbonate ion = aluminum bicarbonate or aluminum hydrogen carbonate
Example 1: Give the molecular formula of aluminum sulfide.
i) Since aluminum is a metal and sulfur is a nonmetal, this compound is classified as an ionic compound.
ii) The cation, aluminum ion, is: Al3+ (if you forget the charge of the aluminum ion, look up the position of Al in the periodic chart).
iii) The anion, sulfide, is: S2- (the –ide suffix indicates that it is a simple anion)
iv) How many Al3+ should combine with the appropriate number of S2- such that the molecule carries no net charge? Al2O3 is the answer.
Example 2: Give the molecular formula of vanadium(III) phosphate.
i) You may not recognize that vanadium is a metal. However, the suffix –ate in the word 'phosphate' is the hint of an oxoanion, a polyatomic ion. You know that this compound is classified as an ionic compound.
ii) The cation, vanadium(III) = V3+
iii) The anion, phosphate = PO43+
iv) How many V3+ should combine with the appropriate number of PO43- such that the molecule carries no net charge? VPO4 is the answer.
Example 3: Give the molecular formula of ammonium sulfate.
i) Both ammonium and sulfate are polyatomic ions, again, this compound is classified as an ionic compound.
ii) The cation is ammonium ion = NH4+
iii) The anion is sulfate ion = SO42-
iv) The molecular formula of the compound is (NH4)2SO4, because it takes two groups of NH4+ to combine with one SO42- to give a molecule that carries no charge.