1.4 Surface Tension
Surface tension is a property of a liquid that allows the surface of the liquid to resist an external force due to the cohesive forces (attractions) between the molecules.
A paperclip or an insect is able to float on the surface of water because the water molecules are strongly attracted to each other and the force applied to its surface is not strong enough to break the molecular interactions.
The stronger the intermolecular forces between the molecules, the larger the surface tension.
Surface tension is what allows liquids to bead (i.e. minimize their surface areas – this is why water forms into round droplets).
Surface tension decreases with increasing temperature. As the particles in a liquid gain kinetic energy, the intermolecular forces are shorter-lived and therefore, weaker.
Given below are surface tensions of some substances at 25 °C.