Metallic Solids

"Sea of Electrons"

Metallic solids are solids composed of metal atoms that are held together by metallic bonds.  These bonds are like huge molecular orbitals that span across the whole solid.  This means the electrons in metallic solids are delocalized.  They are not just held between a couple of atoms in a sigma bond.  Rather, there is a sea of electrons everywhere.  A good picture of a metal solid is that of cation in a sea of electrons.  Because the electrons are delocalized, it is possible to move the nuclei (the cations) without a huge amount of energy.  It is a bit like breaking a pi bond versus a sigma bond.  As such, metals tend to be "soft."  They are malleable which means they can be pounded into sheets.  They are also ductile, which means they can be pulled into wires.  The key idea is that unlike covalent solids, they are not stiff or brittle.  That is because the cations in the sea of electrons can slide around without needing to break any very strong bonds.

Also, because the electrons are delocalized, metallic solids tend to be good conductors of electricity (moving electrons).

Examples of metallic solids include, copper, gold, zinc, .... We tend to think about metallic solids as pure metals, but they can also be combinations of metals like bronze, which is a mixture of copper and tin.