Question

a ionic compound is a type of ionic compound composed of a monatomic metal cation and a monatomic nonmetal anion.

Explanation:

The question is about a type of ionic compound made from a monatomic metal cation and a monatomic nonmetal anion. In chemistry (a subfield of Natural Science), this type is called a "binary ionic compound" or more specifically, a "Type I ionic compound" (where the metal has a fixed charge, typical of main - group metals forming monatomic cations and nonmetals forming monatomic anions). The blank should be filled with "binary" (or "Type I") as this describes the simplest form of ionic compounds with one type of metal cation and one type of nonmetal anion.

Answer:

binary (or Type I)