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JOHN DALTON
He existed from 1766-1844. He was an English chemist. He suggested that matter is made up of small, discrete particles which are like little solid balls. His atomic theory said elements consisted of tiny particles called atoms. It states an element is one of a kind because all atoms of an element are identical. All the atoms that make up the element have the same mass. All elements are different from each other due to different masses. A compound is a pure substance. -
ROBERT BROWN.
He existed from 1773-1858. He was a Scottish scientist. He observed with a microscope that some dead pollen grains suspended in water were constantly moving about randomly in all directions. This is known as ''Brownian Motion''. contributions to botany largely through his pioneering use of the microscope. -
ALBERT EINSTEIN
He existed from 1879-1955. He is a German-born and an American physicist. He explained that the dead pollen grains were moving because they were being bombarded by the moving water particles.He explained that the pollen grains are buffeted by collisions with molecules of water moving randomly in all directions. Einsteins theory and observations showed that the mean distance traveled by a pollen grain subject to random collisions. -
DEMOCRITUS
He existed from 460-361 B.C. He hypothesised that all matter is made up of tiny discrete particles called atoms which are too small to be seen.The theory of Democritus held that everything is composed of "atoms", which are physically, but not geometrically, indivisible; that between atoms, there lies empty space; that atoms are indestructible, and have always been and always will be in motion; that there is an infinite number of atoms and of kinds of atoms, which differ in shape and size. -
ARISTOTLE
He existed from 460-322 BC. He hypothesised that all matter has a continuous composition that can be broken down into smaller and smaller pieces.Aristotle did not believe in the atomic theory and he taught so otherwise. He thought that all materials on Earth were not made of atoms, but of the four elements, Earth, Fire, Water, and Air. He believed all substances were made of small amounts of these four elements of matter.
