Ionic Bonding Chapter 27

The Octet Rule Elements that have 8 electrons in their outer shell are very stable. All atoms want 8 in their outer shell except Hydrogen and Helium which have 2 in their outer shell.

Ionic Bonding Ionic bonding involves the transfer of electrons. i.e one atom gives electrons and one atom takes electrons. Ionic Bonding only occurs between metals and non metals.

Ionic Bonding In an ionic bond: Metals tend to lose electrons. Non Metals tend to gain electrons. When a atom loses or gains an electron it forms a ion.

Ions An ion is any atom with a charge. When a atom loses an electron it gets a (+) charge. When an atom gains an electron it gets a (-) charge.

Ionic Bond An ionic bond is the force of attraction between oppositely charged atoms.

Noble Gases The noble gases are not involved in chemical bonding because they already have a full outer shell and are very stable.

Covalent Bonding A covalent bond is formed when atoms share electrons. Covalent bonding occurs between non-metals.

Covalent Bonding A single covalent is formed when atoms share one pair of electrons. A double covalent bond is formed when atoms share 2 pairs of electrons i.e. O2

Water Molecule

Ionic and Covalent Compounds The type of bonding in a compound has a large affect on its properties.

Properties of Ionic Compounds Made up of crystal lattices. Usually Solid. (strong attraction between oppositely charged ions) High melting and high boiling points (it requires lots of energy to break attraction between ions) Usually solid in water. Conduct electricity when melted or in solution. E.g. NaCl, AlCl3

Properties of Covalent Compounds Consist of separate molecules. Usually liquids or gases (very weak forces between molecules) Low melting and boiling points (low energy required to separate molecules) Usually insoluble in water. Do not conduct electricity.