Ionic and Molecular Substances

A question arose concerning ionic and molecular substances. The Question was:

I'm a little bit confused on ionic and molecular compounds. How do you know which one is which? Is it just that when nonmetals and metals combine they are ionic and anything else is molecular? Would you please clear this up for me?

A metal combined w/ a nonmetal is an ionic substance (ionic bonding)

NaCl

A nonmetal combined w/ a nonmetal is molecular substance (i.e., covalent bonding)

NO₂

A metal with a metal is special case of metallic bonding, so is neither ionic or molecular

Polyatomic ions may be formed between nonmetallic elements using covalent bonds, like

sulfate ion SO₄^2-

These are molecular substances,

but they can form an ionic compound when combined with a metal, like

sodium sulfate Na₂SO₄

To send electronic mail to Dr. Northrup ====> snorthrup@tntech.edu, or call 615-372-3421, or come to Foster Hall 219

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