Answer to Question #156485 in General Chemistry for Leonard

Question

Why does the size of an hydride ion varies to the metal to which it’s bound 

Answer 1

Technically, it maintains the same size, but the reactivity of the hydrogen changes depending on the charge, size and other properties of the metal and other ligands that are on it.

However, because the size of an ion is taken as half the distance between the two nuclei, therefore hydride ion will always have slightly different radius based on this definition.