Aluminium VS Platinum conduction?

The answer lies in the nuclear shielding that occurs in the platinum atom because of the orbital rings. In the platinum atom, there are 6 orbits of electrons. The valence electrons fall in the last orbit with just 1. The aluminium atom only has 3 orbits and therefore has less nuclear shielding. Also if you look at the electron configuration. The p orbit, which is were Aluminium is in, is more "lose" because of less compacting that is occurring. With the d orbital, your electrons are more tided up and not as easy to release and create charges.