NH2- vs. H-: Electronegativity and Basicity

[Avi_R]

Why is NH2- a stronger base than H-. I would think that due to N's greater electronegatavity, it would want to hold on to its electrons more, making it less basic.

 

[lightarrow]

NH2- + H+ --> NH3; (delta)G reaction = -1657 Kj/mol
H- + H+ --> H2; (delta)G reaction = -1649 Kj/mol

So, the reaction NH2- + H2O --><-- NH3 + OH- has a lesser (delta)G than the reaction H- + H2O --><-- H2 + OH-; that is, the first one has a greater equilibrium constant than the second.

with --><-- I mean equilibrium reaction.

 

[Avi_R]

Thanks for the answer, but speaking strictly based on structure, how would we determine this?

 

[lightarrow]

Thanks for the answer, but speaking strictly based on structure, how would we determine this?

I don't think it's possible, at least AFAIK.