what is the surface energy?Define in brief.

Surface: atoms possess higher energy since they are less tightly bound.
Bulk: atoms possess lower energy since they are much tightly bound.
? The sum of all the excess energies of the surface atoms is the
surface energy.
? Surface energy is of the essence of “energy”, and can be defines in
term of Gibbs free energy: dG ? ?SdT +VdP +?dA

System tends to reduce its free energy as it is reaching the equilibrium
state. In some cases, this stable state can be achieved by the reduction
of the surface energy of system.
E.g. a. Smaller drops aggregate into larger ones.
b. Sintering of small metal or ceramic particles under high
temperature.