1. What are Molecules?
Section 15-2

2. Molecules
Smallest part of a compound that has all the properties of the compound. Look at sugar under a microscope. It is made up of many grains. A single grain can be broken down into millions of smaller particles called molecules. A molecule of sugar is the smallest form of sugar that has the properties of sugar.

3. Diatomic Molecules
A molecule which contains two atoms of the same element joined together. Most gas elements form diatomic molecules.

4. Combining Atoms
Different types of molecules are made up of different combinations of atoms. Salt (NaCl) is 1 sodium and 1 chlorine, sugar (C12H22O11), is 12 carbon, 22 hydrogen and 11 oxygen, water (H2O) is 2 hydrogen and 1 oxygen.