Metallic bonding

• Properties of metals - high melting points - good electrical conductivity - good thermal conductivity - malleable - ductile
• metals typically have one, two or three electrons on their outer shell and have low ionisation energies
• the electrical conductivity of metals generally increases as the number of outer shell electrons increase
• metal cations surrounded by delocalised electrons which are free to move and carry a charge - there are electrostatic forces of attraction between the nuclei of the cations and the delocalised electrons (metallic bonding) - giant lattice structure
• melting point - lots of energy is required to overcome the forces within the lattice
• group 1 metals have low melting points
• group 2 metals have higher melting points
• metals in the d block typically have higher melting points as they have more delocalised electrons per ion
• when a potential difference is applied across the ends of a metal, the delocalised electrons will be attracted to the positive terminal of the cell - this movement of electrical charge causes an electric current
• thermal conductivity - free moving delocalised electrons pass kinetic energy along the metal - the cations are closely packed and pass kinetic energy from one cation to another
• when a stress is applied to a metal, the layers of cations may slide over one another, however, the free moving delocalised electrons move with the cations and prevent strong forces of repulsion forming between the cations in one layer and the cations in another layer