The oxygen atom has eight electrons, and often a majority of them are around on the side away from the hydrogen atoms, making this face of the atom negatively charged. Since opposite charges attract, it is no surprise that the hydrogen atoms of one water molecule like to point toward the oxygen atoms of other molecules. W ithin the water, at least a few molecules away from the surface, every molecule is engaged in a tug of war with its neighbors on every side. At the surface things are different. It takes work to pull a molecule up to the surface.
Surface tension plays an important role in the way liquids behave.
If you fill a glass with water, you will be able to add water above the rim of the glass because of surface tension. Y ou can float a paper clip on the surface of a glass of water. Place the paper clip on a fork and lower it slowly into the water. The paper clip is supported by the surface-tension skin of the water. The skin-like surface of the water is depressed under the water strider's feet.