How could/would determine whether a substance is ionic or not?

Question

xishem · Answer

Generally, an ionic compound is a compound consisting of a positively-charged metal cation bonded to a negatively-charged nonmetal anion or polyatomic ion.

anonymous · Answer

An ionic compound usually contains a metal-cation (looses valence electrons to become positive) and a non-metal(anion gains electrons to have complete outer shell- goal of 8 electrons). An exception is polyatomic ions like carbonate(CO3), which has a negative two charge. With polyatomic ions the elements that make up the ion are bonded covalently, the ion as  whole bonds as an ion.

anonymous · Answer

Yeah but all those are answers to "what an ion is"

Determining if a substance is ionic can be done be for example making a solution with water and testing its conductivity (subtract the conudctivity of your plain water first).