Covalent bonds form when atoms share electrons to achieve a full outer shell, giving the molecule an overall charge of zero. Hydrogen always forms covalent bonds because it has only one electron to share. Examples of covalent bonds include hydrogen gas (H2) and hydrogen chloride (HCl), which can be represented using electron-dot diagrams showing the shared electrons. Molecules are combinations of atoms held together by covalent bonds, such as polyatomic ions.

1. Covalent Bonding 1-3

2. Covalent Bonds Sharing of electrons. All atoms still want a full outer shell. All formed molecules must have a stable charge zero. Nonmetal to nonmetal. Hydrogen is a nonmetal and always forms a covalent bond because hydrogen has no shell underneath to give away its only electron.

3. Examples H 2

4. Examples HCl

5. The electron sharing can be represented using an electron-dot diagram. H H H Cl

6. The combination of atoms formed by a covalent bond is called a molecule.

7. Examples Polyatomic ions