How does metallic bonding dictate the properties of metals?

 The metal nuclei are insulated by free- roaming valence electrons.

 Metallic properties due to “sea of electrons” which insulate the positive nuclei.

 Better: steel = Fe + C harder metal  Worse: too much C loss of malleability and ductility cast iron engine block  Better: Bronze = Cu + Sn harder metal, decorative color  Worse: impurities in metals can decrease electrical conductivity

Atomic orbitals overlap to form new orbitals. The more atoms, the more overlapping and the more orbitals formed.

 Overlapping orbitals (close in energy) form energy bands or an electronic highway. e-

 With Mg, although there are 2 s electrons, the p orbitals are there and overlap. This gives the electrons more space to move around in. Hence, electrical conductance.

Semi-conductors only need a little bit of thermal or other excitation to move an electron into the conduction band.

Insulators have a large band gap and hence require a lot of energy to get an electron into the conduction band.

 The bands mean electrons can absorb almost any energy. A vibrating charge is itself an emitter of electromagnetic radiation, so the effect is to cause the metal to re-emit, or reflect, the incident light, producing the shiny appearance.