Heat Capacity: In this final assignment it will be discussed heat absorption, thermal expansions, and thermal conduction – three important thermal phenomena. Heat capacity represents the quantity of heat required to produce a unit rise in temperature for one mole of substance; on a per-unit mass biasis, it is termed specific heat. Most of the energy assimilated by many solid materials is associated with increasing the vibrational energy of atoms; contributions to the total heat capacity by other energy-absorptive mechanisms (i.e., increased free-electron kinetic energies) are normally insignificant. For many crystalline solids and at temperatures within the vicinity of 0 K, the heat capacity measured at constant volume varies as the cube of the absolute temperature; in exces of the Debye temperature, Cv becomes temperature independent, assuming a value of approximately 3R. Thermal Expansion: Solid materials expand when heated and contract when cooled. The fractional change in length is proportional to the temperature change, the constant of proportionality being the coefficient of thermal expansion. Thermal expansion is reflected by an increase in the average interatomis separation, which is a consequence of the assymetric nature of the potential energy versus interatomic spacing curve trough. The larger the interatomic bonding energy, the lower is the coefficient of thermal expansions.