Liquids are held together by van
der Waals attractions, dipole
forces if the molecules are polar, hydrogen
bonds, and electrostatic
attractions between ions of a molten salt.
We will be concerned mainly with molecular liquids such as
water, in which hydrogen bonds and van der Waals and dipole
forces are the most important factors.
Not all molecules in a liquid move with the same speed. In
general, the higher the temperature,
the faster they move; but the
molecules in a liquid have a range of speeds rather than one
As molecules collide with one another they gain and lose
energy, but the liquid as a whole maintains a velocity
distribution of the type shown below. Increasing the
temperature simply shifts the distribution
maximum to higher speeds.
Go on to the next page to see this animated.