pentavalent

Adjective

Meaning

Having a valence of five; -- said of certain atoms and radicals.

Source: Webster's dictionary

fifth decimal tenth tithe hundredth duodecimal centesimal pentad powerfulness quinquivalent pentahydric

Pentavalent ammonia is known as λ 5 -amine, or more commonly, ammonium hydride. Source: Internet

Pentavalent bohrium should have a larger ionic radius of 83 pm. Source: Internet