All matter is made of atoms . Atoms of different elements have different weights and different properties. The concept of a molecule . A cluster of two or more atoms bound together is called a molecule . The properties of a molecule are different from those of the atoms comprising it.
Molecules have definite, predictable shapes and structures .
Molecules attract each other . This causes gases to become liquids and liquids to become solids as the temperature decreases. In a chemical reaction atoms are neither created, destroyed, divided into parts, or converted into other kinds of atoms in the course of a chemical reaction. Figures illustrating the concept of a balanced chemical equation. Combustion of butane .