Why does copper have a higher melting point than aluminium?

[KingCrimson]

Why does copper have a higher melting point than aluminium? Why does the melting point increase as you go down groups anyway?
Aluminium has higher charge (+3) and a smaller radius, meaning that there is a higher charge density and thus stronger forces of attraction to the lattice. While copper has a charge of +1 and a bigger radius. However, Copper has a higher number of protons, or a stronger positive charge in the nucleus, is this the reason ?

 

[DaveC426913]

It's a combination of things.

Have a look at this chart:
http://www.periodictable.com/Properties/A/BoilingPoint.html

 

[Borek]

Aluminium has higher charge (+3)

Metallic aluminum has no charge and consists of neutral atoms.