non-valent
/nɒnˈveɪlənt/ /nɒnˈveɪl(ə)nt/Chemistry
adjective
Originally: (now rare ) not readily forming chemical bonds; inert. Later: having a formal oxidation state of zero; = zerovalent.
Origin
Late 19th century; earliest use found in Proceedings of the Royal Society of London. From non- + -valent.