What is the difference between solids, liquids and gases? How does each state behave?
- The kinetic theory of matter states that particles are in constant motion and there are forces of attraction between them.
- The attraction between particles in solids is strong and they are packed very close together.
- The particles in liquids are close together and they don't have a fixed shape.
- The particles in gases are far apart and have weak forces of attraction between them.
Robert Brown, 1827
In 1827, biologist Robert Brown was looking through a microscope, studying pollen grains in water.
He observed something amazing. The grains kept jiggling about, and never slowed down, even when he looked at them again much later.
This became known as Brownian motion.
But Brown himself couldn't work ...
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