In a metal, the atoms lose several of their outer electrons which drift between the metal ions as free electrons.
Ions arranged in layers. Giant lattice structure forms.
As they have lost a few electrons, the atoms become positive ions. (+)
Free ('delocalised') electrons. (-)
Strong forces hold the positive ions and electrons together.
The large number of free electrons makes all metals good conductors of electricity and heat.
The regular structure means the layers of atoms can fairly easily…