Answer to Question #156309 in General Chemistry for Janet

Question

Why does the size of an hydride ion varies with the metal ion to which it's bonded?

Answer 1

There may some slight increase in the size of the H^- ion with metals that hold onto the valence electron(s) less strongly, just because the electron spends less time, on the average, near the positive ion. For example, the hydride ion may be larger for cesium vs lithium hydride.