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400
Aristotle (B.C)
He believed that all matter was made of "The 4 element" which are: fire, earth, air, and water.
He didn't have proof to support his theory. -
400
Democritus (B.C)
He discovered that matter can't be divided into smaller pieces. The smallest piece of matter is atoms.
He used theories and observed how matter could be formed into different shapes and sizes. -
Dalton
He came up with the atomic theory. He discovered certain gases can only be put together in certain proportions, even if two different combined elements share the same common elements or group elements.
He use the 5 parts of the atomic theory.
1st: pure elements made up particles called atoms
2nd: atoms are the same for that element
3rd: atoms of differ element can be told apart bt atomic weight
4th: atoms element come together to form chemical compounds.
5th:atoms are indestructible in C. React -
Thomson
He discovered the electron was smaller and atoms were made of much smaller particles. He used a cathode ray tube,pumped all the air out,placed two medals in it and hooled to a source of energy.He saw a red ray go through the medals and asked did it have a electrical charge. -
Rutherford
The experiment he performed that made he realized that the atom must have almost all of its mass concertrated at its center. -
Bohr
He proposed that electrons orbit the nucleus without losing energy. One observation was the experiment that showed if an orbit was big size i had an lot of energy. -
Heisenburg and Schrodinger
Both men had essentially the same theory. It proved that no experiment can measure the position and momentum of a quantum particle.
