Assign each species to the expression that most accurately describes the basic units of that substance. categories: single atoms- copper, helium, ag, diatomic molecules -iodine, fluorine, br2 molecules -no2, kmno4, formula units - c3h8, mgcl2, hgbr2, ba(oh)2 this is what i think it is but not sure.

Atoms are the smallest form of the substance. examples of atoms are in elemental forms such as copper, helium, silver. Diatomic molecules are made up of identical atoms. Examples are I2.. F2 and Br2. Formula units are those compounds that are made up of two or more elements such as -No2, KMnO4,C3H8, MgCl2, HgBr2, Ba(OH)2

ATOMS - copper, helium, silver

MOLECULES - iodine, fluorine, bromine, NO₂, C₃H₈

FORMULA UNITS - KMnO₄, MgCl₂, HgBr₂, Ba(OH)₂

Further Explanation

The basic units or representative units of a substance may be atoms, ions, molecules, or formula units.

If the substance are elements in monatomic form, their representative unit is  "atoms". If they are diatomic elements, then their representative unit is "molecule".If the substance is a compound, the representative unit depends on the kind of bonding. If the substance is ionic in nature, its representative unit is called a "formula unit". If the substance is covalent or molecular, the representative unit is also called "molecule".Recall that ionic compounds are substances that are made up of metallic and nonmetallic elements that are chemically bonded. Covalent or molecular compounds are those that are only composed of chemically bonded nonmetal elements.If pertaining to the component ions of an ionic compound, the representative particles are called "ions".

Therefore, the substances in the problem may be grouped to the following representative particles:

ATOMS - copper, helium, silver

MOLECULES - iodine, fluorine, bromine, NO₂, C₃H₈

FORMULA UNITS - KMnO₄, MgCl₂, HgBr₂, Ba(OH)₂

LEARN MORELearn more about Compounds Learn more about Stoichiometry

Keywords: representative units, atoms, molecules, formula units

Sorry i dont understand the question can you rephase it?