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460 BCE
Democritus
Democritus was around starting from 460 BCE. Some say 490 BCE. He expanded the atomic theory of Leucippus. He maintained the impossibility of dividing things ad infinitum. While on the journey of discoveries, he argued the eternity of exsisting nature, of void space, and even of motion. He stated that atoms, being impenetrable, made these things up. He introduced later the "hypothesis of images/idols". This concluded him to settle with his discovery, and account for the popular notions of diety. -
Period: 460 BCE to
The History of The Atom
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Dalton
He mainly searched for an explanation of the law of multiple proportions to the idea that chemical combination consists in the interaction of atoms. This led him to test with many different physical properties of the atmosphere and other gases. His theory discovered that all things are made of atoms, they can't be created, subdivided, nor destroyed, and in chemical combinations atoms are combined, seperated, or re-arranged. -
Thompson
Thompson discovered the electron by experimenting with a Crookes, or cathode ray, tube. He demonstrated that cathode rays were negatively charged. His theory came into exsistance in 1903. He proposed a model of the atom known as a plum or chocolate cookie. Until the 19th century, the concept of the atom was similar to a small billiard ball. In 1897, that all changed when he discovered the electron! Thompson's atomic theory suggested that the atom is not indivisible, but made of smaller pieces. -
Rutherford
Rutherford was a very devoted scientist and studied hard in schooling. In 1910, he studied and discovered the scatterings of alpha rays. He later, in that studied found out that the scattering led to his concept of a nucleus. -
Bohr
Niels Bohr, although born in 1885, discovered quite equally to the contribution of the others across the timeline. His discoveries of the electron and radioactivity at the end of the 19th century led to many different models for the structure of the atom. In 1913, Niels Bohr proposed a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities. Electrons should move around the nucleus but only in prescribed orbits.
