1、,SURFACE TENSION,SURFACE TENSION,Whats going on at the surface of a liquid?,Whats going on at the surface of a liquid?,Lets take a look!,Particles that make up a liquid are in constant random motion; they are randomly arranged.,You might expect the particles at the surface, at the micro level, to fo
2、rm a random surface, as shown below.,You might expect the particles at the surface, at the micro level, to form a random surface, as shown below.,= intermolecular attractions,But how do intermolecular forces influence the surface?,Under the surface, intermolecular attractions pull on individual mole
3、cules in all directions,= intermolecular attractions,= intermolecular attractions,= intermolecular attractions,At the surface, pull on the molecules is laterally and downward; there is negligible intermolecular attractions above the molecules (from the medium above, such as air). SO, the net force o
4、n surface molecules is downward.,The result of this downward force is that surface particles are pulled down until counter-balanced by the compression resistance of the liquid:,Surface molecules are compressed more tightly together, forming a sort of skin on the surface, with less distance between t
5、hem compared to the molecules below.,Surface molecules also form a much smoother surface than one would expect from randomly moving molecules.,This explains the characteristic rounded shape that liquids form when dropping through the air: The molecules are all being pulled toward the center.,This ex
6、plains the characteristic rounded shape that liquids form when dropping through the air: The molecules are all being pulled toward the center.,Water in particular has a very high surface tension. What property does water have that would give it such a strong surface tension?,This is the water strider insect. Have you seen one?,How is this possible?,
