Why phosphine is more basic than ammonia?

Answer 1

This is because of the electronegitivity and size difference in the elements N and P. N has a higher electronegitivity and pulls the electrons in the N-H bonds toward itself, creating a more polar bond than the P-H bond. N is smaller than P thus it is a better lewis base, being able to form more stable sigma bonds. Both of these things cause NH3 to more readily take up a proton from solution.

Answer 2

Phosphine is more basic than ammonia because phosphorus is less electronegative than nitrogen, allowing the lone pair of electrons on phosphine to be more available for donation. Additionally, the larger size of phosphorus in phosphine leads to weaker P-H bonds, making it easier for the lone pair to be donated.

Answer 3

Phosphorus is less electronegative than nitrogen, which makes it easier for phosphine to share its lone electron pair with a hydrogen ion.