Compounds are created when atoms combine with a chemical bond. The smallest unit of a compound is called a molecule.

​

Compounds and Molecules

Compounds are represented using chemical formulas which consist of the chemical symbols of the atoms in one molecule of a compound.

​

​Representing Compounds

Chemical formulas also include subscript numbers that indicate how many atoms of an element are in a molecule. If there is no subscript number, it indicates that there is only one atom of that element.

​

​Representing Compounds

​Atoms have a tendency to fill their valence shells with the maximum number of electrons so the would lose, gain or share electrons to achieve this. This leads to atoms having a chemical bond between them which forms molecules. The type of bond depends on whether the electrons were gained, lost or shared.

​

The Octet Rule

​A covalent bonds occurs when atoms share valence electrons in order to satisfy the Octet Rule and fill their valence shell.

Covalent Bonds

​Ionic bonds form when one atom loses an electron and another atoms captures the lost electron. As we previously learned, gaining or losing an electron changes the electromagnetic charge of an atom, which is now referred to as an ion. A chemical bond is formed when positive and negative ions are attracted to each other, creating a molecule.

​

Ionic Bonds