-
200
440 BC- Democritus
Democratis said that all atoms are small, hard particles and that eventually you would end up with a particle that could not be cut. -
200
Aristotle- 382 BC
He believed that you would never end up with a particle that could not be cut. He had such a strong influence on people's ideas that people believed he was right. -
Dalton
Dalton's theory stated that all substances are made of atoms. Atoms are small particles that cannot be created, divided, or destoryed. Atoms of the same element are exactly alike, and atoms of different elements are different. Atoms join with other atoms to make new substances. -
Thomson
Thomson discovered that there are small particles inside the atom, which means that atoms can be divided into even smaller parts. He thought that the electrons were mixed throughout the nucleus. -
Schrodiger and Heisenberg
They explained the nature of electrons in an atom. They said that electrons do not travel in definate paths as Bohr suggested. -
Rutherford
Rutherford thought that atoms are soft blobs of matter. He expected the particles to pass right through the gold in a straight line. But some of the particles were deflected. Some even bounced straight back. -
Rutherford
In 1911, Rutherford revised the atomic theory. He proposed that in the center of the atom is a tiny, extremely dense, positively charged part called the nucleus. -
Bohr
He studied the way that atoms react to light. His results led him to propose that electrons move around the nucleus in certain paths, or energy levels. -
Period: to
The Development of Atomic Theory
