A sphere of radius R is composed of atoms of radius a.Make the assumption that the surface
atoms occupy a spherical shell 2a thick.Use the packing fraction to correct for the interstitial
volume.You do not need to
consider the granular nature of the particle any further (ignore
packing, stacking, surface corrugations, etc.).
Fluids behave as though they have a surface composed of an elastic skin
which is always in tension.There
are many manifestations of surface tension you can observe
everyday.Here are some
fundamental properties of surface tension.
The surface tension causes an increased chemical potential for a
molecule inside a droplet.This
is manifested as an increase in the vapor pressure P of the liquid
droplet compared to that of the bulk liquid P0. The is
described by the Kelvin equation.Two radii of curvature appear in the result, r1 and r2.For a sphere both terms are equal, but
for a cylindrical surface one term vanishes because one radius is