Metals share a constellation of properties, all traceable to their electron behavior:

• Conductivity — free-flowing electrons carry electrical current and transfer thermal energy
• Malleability — metal atoms slide past each other without breaking bonds, allowing reshaping
• Luster — free electrons absorb and re-emit light at the surface, giving metals their shine
• Ductility — metals can be drawn into thin wires because their atomic layers glide smoothly

The sea of electrons model ties it together: metal atoms release their outer electrons into a shared pool that flows freely through the lattice. That single idea explains every metallic property.