Moles in 1 mole nitride ion

[xiphoid]

Homework Statement

The number of moles of valence electrons in 1 mole nitride ions are?

Homework Equations

Nitride ion- N₃^-

The Attempt at a Solution

The number of electrons are 8.
Therefore number of moles should also be 8?

 

[AGNuke]

Nitride ion : N^3-. The one you mentioned is Azide ion : N₃^-.

The rest is correct.

 

[xiphoid]

That was my typing mistake!

Nitride ion : N^3-. The one you mentioned is Azide ion : N₃^-.

The rest is correct.

 

[JohnRC]

Quite irrelevant to your homework, but the nitride ion is a complete and utter myth. (In spite of what a lot of textbook writers, who really should know better, have to say).

If you could manage to get a nitrogen atom to accept two extra electrons -- in itself a most unlikely feat -- the extra repulsion of those two negative charges to an incoming negatively charged electron would make it quite impossible for the electron to remain anywhere near that particular atom/ion.

 

[AGNuke]

the nitride ion is a complete and utter myth.

Maybe. But Nitrides "exists" in ionic lattice, explain that. But I support the fact that Nitride ions are not present in aqueous form or "maybe" in independent (gaseous) form, but don't outright its existence altogether. This I know that Nitride forms ionic compounds, not covalent compounds.

Come on, even Carbides, Hydrides are present, so why not Nitride? I am pretty sure hydride suffers more than Nitride, as its ionic radius is equivalent to Bromide(!). I would really like to know what you think. You argument seems... weak. Ion will have high potential energy, worse cases also exist.

 

[JohnRC]

nitrides and carbides are polar covalent network compounds, not ionic lattices. That is why they are hard and refractory. The best calculation methods available show an average charge of approximately 1 electron (not 3) on nitrogen atoms in any refractory nitride.
With carbides, there are non-refractory carbides, e.g. CaC₂, but that is an "acetylide" based (notionally) on C₂^2–, an associate base for acetylene acting as an acid. Metallurgists often, and chemists occasionally like to consider compounds like nitrides in a "formal charge" model, where they assign a formal charge of –3 to the nitrogen atoms in a polar network compound. They similarly tend to regard silica, the standard example of a polar network compound, as formally made up of Si⁴⁺ and O^2– ions. But it is purely a formal accounting, that has nothing to do with reality.

Consider a calcium nitride lattice with a missing electron, and imagine that the lattice is indeed made up of Ca²⁺ and N^3– ions. Will the missing electron attach itself to a calcium ion (electron affinity 11.9 volt) or a "nitride ion" (electron affinity negative)? Having answered this question, it will become obvious to you why in an imaginary ionic lattice made up of these two ions, nearly all of the valence electrons would migrate from the nitrogen atoms to the calcium atoms, resulting in the polar covalent network solid that we actually observe.