It depends on the charge of the cation. Examples
NaCl, MgCl2, FeCl3
The formula is KCl. This is an ionic compound consisting of equal numbers of potassium cations and chloride anions.
The formula for the ionic compound barium chloride is BaCl2.
The chemical formula for Calcium Oxalate is CaC2O4
PbCl4 is the formula of the compound lead chloride.
The formula of ammonium chloride is NH4Cl
The formula is KCl. This is an ionic compound consisting of equal numbers of potassium cations and chloride anions.
Magnesium forms divalent cations and chlorine forms monovalent anions; therefore, the binary compound of magnesium and chloride has the formula MgCl2.
A Roman number in the name of an ionic compound gives the absolute value of the oxidation number of that element in the compound which immediately precedes the Roman number. This is most common with cations of elements, such as copper and cobalt, that can form stable cations in more than one oxidation state. Copper(II) chloride, for example as the formula CuCl2 while copper(I) chloride has the formula CuCl.
There is no compound with the formula Al2Cl3. But AlCl3 is aluminum chloride.
The formula for the ionic compound barium chloride is BaCl2.
The chemical formula for Calcium Oxalate is CaC2O4
Copper(II) chloride is already a compound; its formula is CuCl2
PbCl4 is the formula of the compound lead chloride.
Strontium chloride is a compound of lithium and chlorine with the formula SrCl2. Lithium chloride is a compound of lithium and chlorine with the formula LiCl.
Sodium chloride is an inorganic ionic salt.
The formula of ammonium chloride is NH4Cl
Sodium chloride is a compound; a compound has a chemical formula (or a formula unit) not a chemical equation. The formula unit of sodium chloride is NaCl.