Cohesion and Surface Tension

Cohesion

CohesionMolecules are attracted to

other molecules of the same kind. ◦ For example, as you can see from the picture above the oxygen

end of water has a negative charge and the hydrogen end has a positive charge. The hydrogen atoms of one water molecule are attracted to the oxygen atoms from other water molecules. This attractive force is what gives water its cohesive properties.

Water Cohesion Water has a very simple atomic structure. This

structure consists of two hydrogen atoms bonded to one oxygen atom. The nature of the atomic structure of water causes its molecules to have unique electrochemical properties. The hydrogen side of the water molecule has a slight positive charge. On the other side of the molecule a negative charge exists. This molecular polarity is responsible for its strong surface tension .

Surface Tension

Surface TensionSurface tension is the name we

give to the cohesion of water molecules at the surface of a body of water. The cohesion of water molecules forms a surface "film" or “skin.” Some substances may reduce the cohesive force of water, which will reduce the strength of the surface “skin” of the water.