Cleansing Action of Soap:

Soaps contain two chemically distinct parts: a long hydrocarbon tail and the other negatively charged head. The long hydrocarbon tail is nonpolar and water repelling, i.e. insoluble in water.

When a soap is dissolved in water, the molecules clump together in a spherical fashion as clusters called micelles. The tail stick inwards and the head outwards.

In cleaning, the long hydrocarbon tail attaches itself to oily or dirty part which is nonpolar and insoluble in water. The dirt is, thus, enveloped in the nonpolar end of soap micelles. The negatively charged heads of soap molecules make the micelles soluble in water. Thus, the dirt is washed away with soap.

Formation of micelles