Surface Tension – Surface tension is a result of the interactive forces between the molecules in the surface layer of the liquid (the forces may be dispersive, polar or ionic). Surface tension is defined as the force per unit length in the surface of a liquid. It has the dimensions of m = +1 and t = -2 which is also equal to the energy per unit area. The spherical form of a liquid droplet is a direct result of the surface tension. Considering two liquids that are immiscible, the immiscibility is not due to the molecules of one liquid repelling those of the other but due to the intermolecular forces between like molecules being very much greater than the force between the unlike molecules. For example n-heptane is not miscible with water because the attraction forces between like water molecules and the attraction forces between like n-heptane molecules is much greater than the attraction forces between a water molecule and an unlike n-heptane molecule. Unless containing induced like charges or induced like magnetic poles matter cannot repel itself.

Further Information on this Topic can be found in the books of R.P.W. Scott by following the listed links