- Surface tension has to do with the attractions or internal forces operating within a liquid between the molecules that it is composed of.
These are referred to as cohesive forces
- Surface tension is the reason why drops of water (H2O) bead on clean and polished surfaces and form perfect spheres in isolation.
Water molecules are strongly attracted to each other due to the hydrogen bonding between them.
The water molecules on the surface of water are normally exposed to the air molecules as well as to the internal water molecules, but are much more attracted to the internal water molecules. This is due to the hydrogen bonding between water molecules referred to above..
This causes the surface water molecules to be strongly pulled into the body of the water, aiming to achieve the lowest energy state, which happens to result into, as close as possible, a spherical shape.
- Surface tension has many other far reaching implications.
In general, surface forces work to decrease the surface free energy of liquids and solids to reach the lowest possible and most stable level of energy. Liquids are drawn into spheres because spheres enclose a minimum ratio of surface area to volume. Due to gravitational forces, the spheres are deformed. The degree of deformation depends on the surface tension of the liquid.