- The molecular orbital theory of solids The molecular orbital theory ofsmall molecules can be extended to account for the properties of solids, which are aggregations of a virtually infinite number of atoms. This approach l5 strikingly successful for the description of metals, for it may be used to explain their characteristic luster, their good electrical and thermal conductivity, and their malleability. All these properties stern from the ability of the atoms to contribute electrons to a common sea. The luster and electrical conductivities stem from the mobility of these electrons, either in response to the oscillating electric field ofan incident ray of light or to a potential difference. The high thermal conductivity is also a consequence of electron mobility, because an electron can collide with a vibrating atom, pick up its energy, and transfer it to another atom elsewhere in the solid. The ease with which metals can be mechanically deformed is another aspect of electron mobility, because the electron sea can quickly readjust to a deformation of the solid and continue to blnd the atoms together.