A molecule is a chemical unit containing two or more atoms joined together. Molecules may consist of the same type of atoms or different types of atoms. The properties of a compound are totally different than the elements that make them up. See Figure 1.3. In these models, we use red to represent oxygen, white to represent hydrogen and black to represent carbon.
Atoms consist only of one type of element.
Molecules consist of more than one type of element. A compound is composed of specific elements in a definite proportion by weight. If matter is not uniform throughout, then it is a heterogeneous mixture . Example- a cup of coffee with sugar in it that has not been stirred. If matter is uniform throughout, it is a homogeneous mixture .