Metals can have different properties depending on their atomic configuration and molecular properties. Generally metals are good conductors of electricity and heat. They also display magnetic properties. Typically metals are malleable and ductile. They will deform under stress without cleaving. Metals are shiny and lustrous. Sheets of metals beyond a few micrometres thick will be opaque but golf lead transmits green light.
Although metals generally have higher densities than most non-metals, there is a wide variation in their densities. Lithium is the lease dense solid element whereas osmium is the densest solid element. Alkali and alkaline earth metal in group I A and II A are referred to as the light metals. This is due to their low density, low hardness and low melting points. The high density of most metals is due to the tightly packed crystal lattice of the metallic structure. The strength of the bonds of different metals reaches a maximum around the center of the transition metal series. Those elements have large amounts of delocalized electrons in tightly binding type metallic bonds. However, other factors are also involved. These are atomic radius, nuclear charge, number of bond orbitals, overlap of orbital energies and crystal forms.