Nonmetallic as an adjective is of, relating to, or having the properties of a nonmetal while Metalloid as a noun is an element, such as silicon or germanium, intermediate in properties between that of a metal and a nonmetal; especially one that exhibits the external characteristics of a metal, but behaves chemically more as a nonmetal
Part of speech: adjective
Definition: of, relating to, or having the properties of a nonmetal not metallic
Part of speech: noun
Definition: an element, such as silicon or germanium, intermediate in properties between that of a metal and a nonmetal; especially one that exhibits the external characteristics of a metal, but behaves chemically more as a nonmetal
We hope you now know whether to use Nonmetallic or Metalloid in your sentence.