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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: GreenAssailant on December 10, 2011, 09:03:11 PM

Title: [CHMA] Question about Ionic Compounds; they are technically polar right?
Post by: GreenAssailant on December 10, 2011, 09:03:11 PM
An Ionic Compound is technically a dipole right? This is because it has opp. charges on opp. sides of the compound, and there is completely unequal sharing (this is because one atom literally took away a significant amount of e- density from the other, more than that of polar covalent bonds).

(ie. within the crystal lattice structure, most of the e- density is possessed by Cl for instance (if NaCl), while Na is deficient.)
Title: Re: [CHMA] Question about Ionic Compounds; they are technically polar right?
Post by: UG on December 11, 2011, 05:34:33 PM
Yes, ionic compounds are polar. Although pure ionic bonding is not seen, all ionic bonds have a degree of covalent bonding.
Title: Re: [CHMA] Question about Ionic Compounds; they are technically polar right?
Post by: fledarmus on December 12, 2011, 04:17:24 PM
Hmmm, I wouldn't be sure how to answer that question...

In the solid state, I don't think you could point to a specific bond between an anion and a cation, especially in the elementary single atom cases (eg NaCl, KCl, NaBr, etc.). As I understand it, in the crystal structure, a cation is surrounded by a number of anions all at the same distance, each of which is surrounded by a number of cations all at the same distance. You really couldn't pick a single cation and anion and say those two atoms were bound to each other with a polar bond.

The same thing happens in an aqueous solution - all of the anions are surrounded by water molecules and all of the cations are surrounded by water molecules, and you really don't see bonds between the anions and the cations that you could call polar bonds.

Only in the gas phase do you really see a single cation attached to a single anion in a way that you could say might be similar to a polar bond, but this isn't a very stable form and they will accrete readily to any other collections of anions and cations to form the solid structure described above.