1. Number of delocalised electrons per atom - a higher number of delocalised electrons per atom leads to a stronger metallic bond due to increased electrostatic attraction between the metal cation and the delocalised electrons.
2. Charge of the metal cation - the greater the charge on the cation, the stronger the electrostatic attraction between the cation and the delocalised electrons.
3. Size of the metal cation - the smaller the cation, the closer the delocalised electrons are to the positive nucleus and the stronger the metallic bond.

A metallic bond is the electrostatic attraction between positive metal ions and delocalised electrons.

Metals have a giant lattice structure consisting of positively charged metal cations arranged in a regular 3D pattern. The outer electrons of metal atoms leave to become delocalised, moving freely between the cations in the lattice structure.

They have delocalised electrons that can flow freely through the lattice to transfer charge and heat energy.

There are strong electrostatic forces of attraction between metal atoms and the sea of delocalised electrons which require a lot of energy to break.

The layers of the cation lattice can slide over one another because there are no bonds locking individual cations together.

They have strong metallic bonds between cations and delocalised electrons which require a lot of energy to break.