Ionic and Covalent Bonding explained by dogs, courtesy of SnuggliePuppy.

The energy changes in the formation of an ionic compound can be predicted using the Born-Haber Cycle.

Watch the Formation of Ionic Compounds video.

Ionic Compounds are hard because of the Coulombic attractions between cations and anions.

Sapphires are made using aluminum cations and oxide anions. These small, highly charged ions produce a substance whose hardness is second to diamond.

Sapphire is rare in nature, but is now manufactured in large quantities.The video shows how it is made.