Small drops of mercury form a spherical bead

Particles of soil at the bottom of river remain separated but they stick together when taken out

A molecule in the bulk of liquid experiences equal intermolecular forces from all sides.

The molecule in the bulk of liquid does not experience any net force.

For the molecule on the surface of liquid, net attractive force is towards the interior of the liquid due to the molecules below it.

Liquids tend to minimize their surface area.

The molecules on the surface experience a net downward force and have more energy than the molecules in the bulk.

Liquids tend to have minimum number of molecules at their surface.

If surface of the liquid is increased by pulling a molecule from the bulk, attractive forces will have to be overcome.

The energy required to increase the surface area of the liquid by one unit is defined as surface energy.

Its dimensions are J m–2.

Surface tension is defined as the force acting per unit length perpendicular to the line drawn on the surface of liquid.

Surface tension is denoted by Greek letter (Gamma).

Surface tension has dimensions of kg s–2 and in SI unit it is expressed as N m–1 .

The lowest energy state of the liquid will be when surface area is minimum.

Spherical shape satisfies lowest energy state, that is why mercury drops are spherical in shape.

sharp glass edges are heated for making them smooth.

On heating, the glass melts and the surface of the liquid tends to take the rounded shape at the edges, which makes the edges smooth. This is called fire polishing of glass

Surface tension causes liquid to rise or fall in capillaries, wetting things by spreading thin films across surfaces. Gravity causes droplets to flatten on flat surfaces, while gravity free environments have perfectly spherical drops. Surface tension's magnitude depends on attractive forces between molecules, with larger forces causing larger tension.