electronegativity difference NaH

Radwa Kamal

Although the electronegativity difference between sodium and hydrogen in NaH is less than 1.7 , it is ionic bond WHY??

chemisttree

Who told you it was ionic?

Radwa Kamal

Any alkaline metal hydride is ionic

Ionic hydrides
Ionic or saline hydride, is a hydrogen atom bound to an extremely electropositive metal, generally an alkali metals or alkaline earth metals.
source:http://en.wikipedia.org/wiki/Hydride#Ionic_hydrides

chemisttree

Do you think it is purely ionic or might it have a bit of covalent character to it?

Radwa Kamal

I think it is purely ionic because for metals with weak metallic bond like alkaline metals it's a must to lose its valence electron completely for them they are are rarely found in covalent compounds.

alxm

Bah, everything's got a bit of a covalent character to it and vice-versa :) Do the actual QM calculations and you won't find nice integers popping up very often..

Radwa Kamal

Thanx 4 enrichin me by this info in fact my study is somehow limited cuz am still in high school I didn't study QM calculations

nimmysnv

Hi,

This is the same as, I have heard about as, this is what I have studied in my time.

Thanks!

chemisttree

With an electronegativity difference of only 1.7 it is likely a very polarized covalent bond or an very covalent ionic bond. Semantics.

pseudophonist

The only way I can tell to distinguish the two cases is on a macroscopic level. Lets face it, on a quantum level there's basically no straightforward way of telling ionic from covalent. (all the atoms are in a lattice and there's electrons everywhere)
So, if you hit a large crystal of NaH with a hammer, would it shatter? if you melt NaH (in an inert atmosphere), will it conduct electricity?
My gut says yes to both, and therefore I would say NaH is ionic.

ranadeep

Yea its a Ionic Compound ( due to its properties) with more Covalent Character : )
We know nothing is Purely(100%) ionic or covalent : )