Answer:
Atom / Compound / Elements/ Mixtures
Step-by-step explanation:
ATOM: the smallest component of an element having the chemical properties of the element, consisting of a nucleus containing combinations of neutrons and protons and one or more electrons bound to the nucleus by electrical attraction; the number of protons determines the identity of the element.
ELEMENT: Chemistry. one of a class of substances that cannot be separated into simpler substances by chemical means.
COMPOUND: a pure substance composed of two or more elements whose composition is constant.
MIXTURES: an aggregate of two or more substances that are not chemically united and that exist in no fixed proportion to each other.