Here are the answers to my last blog, 22nd July 2012
Each sodium ion (Na+) is surrounded by six chloride ions (Cl-). And each chloride ion is surrounded by six sodium ions. Since there are equal numbers of sodium and chloride ions the formula is NaCl.
Sodium chloride is held together by ionic bonds. An ionic bond is an electrostatic attraction between oppositely charged ions in a crystal lattice.
Hence, in sodium chloride each sodium ion, Na+, is attracted to the six chloride ions, Cl-, that surround it. And similarly, each chloride ion is attracted to the six sodium ions that surround it.
Phew! That was a lot of reading. So here’s my favourite picture of sodium chloride illustrating the cubic structure of the crystals.
The shadows cast by the crystals really bring out their cubic structures into sharp relief.