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201
Artisole- 382 B.C.
Disagreed with Democritus's theory and believed that you would never end up with a particle that could not be cut. He has such a strong influence, that people believed him even though he was wrong. -
Dalton- 1803
Published the Atomic Theory that stated:
-All substances are made up of atoms. Atoms are small particles that cannot be created, divided, or destroyed.
-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-1897
British scientist who showed there was a mistake in Dalton's theory. He said there are small particles inside the atom. This means that atoms can be divided into even smaller parts. Discovered the negatively charged particles called electrons. He created a new model of the atom which is sometimes called the plum-pudding model. -
Rutherford- 1909
A former student of Thomsons who decided to test his theory. His expierment was called the Gold-Foil Expierment. During his test, most of the tiny particles went straight through the gold foil, with a small number that was deflected, some particles even bounced right back. He realized that in order to explain this, atoms must be considered mostly empty space, with a tiny part made of highly dense matter. -
Rutherford- 1911
He revised the atomic theory. He proposed that in the center of the atom is a tiny, extemly dense, positivly charged part called the nucleus. Because like charges repel, Rutherford reasoned that positivly charged particles that passed close by the nucleus were pushed away by the positive charges..From his results, he calculated that the diameter of the nucleus was 100,000 times smaller than the diameter of the gold atom. -
Bohr- 1913
Niels Bohr, who studied with Rutherford, studied the way atoms react with light. His results led him to propose that electrons move around the nucleus in certain paths, or energy levels. In his model there are no paths between the levels. But electrons can jump from a path in one level to a path in another. Bohr's model was a valuble in predicting some atomic behavior. -
Schrodinger and Heisenberg
Erwin Schrodinger and Werner Heisenberg did especially important work. They further explained the nature of electrons in the atom. They determined electrons do not travel in definate paths as Bohr suggested. The exact path of an electron cannot be predicted, They are somewhere in the electron clouds. They created the current model of the atom. -
Democritus- 440 B.C.
Democritus thought that if you continue to cut something in half, you would eventuaually end up with a particle that could not be cut, he called this an atom. He said that all atoms are small, hard particles. They were made up of a single material formed into different shapes and sizes.
