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Democritus's Atom Theory
Democritus, a Greek philosipher, is the first person to think of an "Atom" around 450 B.C, believing it to be the smallest part of a piece of matter. He explained that if you take a piece of matter and break it in half until it can no longer be broken anymore, It must be at its smallest state, and named it the atom. -
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Aristolte's 4 Elements Theory
Aristotle, also a Greek philosopher, had a differing theory from Democritus, believing that all matter wasn't composed of Atoms, but instead by the 4 elements (Water, Earth, Fire, Air). He adopted this theory around the same time Democritus was developing his own theory. This theory explained nearly nothing because it is highly inaccurate. -
John Dalton becomes "Father of Atomic theory"
Scientist John Dalton was the first person to introduce the theory that Atoms make up elements, in the late 1700's and early 1800's. He believed that Atoms couldn't be created or destroyed, only changed. He not only answered the question of whether or not atoms make up elements, but also said that atoms of the same element are identical and atoms of differing elements are different. Because his theory was largely accurate, he is known to be the"Father of Atomic Theory". -
The Curies relate Atoms to Radiation
Pierre and Marie Curie were both scientists famous for their ground breaking research on Radiation and elements during the late 1800's, who stated that radioactive materials cause atoms to break down spontaneously, releasing radiation in the form of energy and subatomic particles. -
Henri Becquerel discovers radiation
Henri Becquerel was the first person to discover Radiation and work on the research of radiation with both, Marie and Pierre Curie. He recieved a Nobel Piece prize alongside Marie curie in 1903 for his contributions to Science. -
Thomson's discovery of the Electron
J.J Thomson was an English Physicist who is known for experimenting with Cathode ray tubes and discovering the electron of an atom in the 1890's. His experiments showed that not only that cathode rays were over 1000 times lighter than the hydrogen atom, but that their mass was the same no matter what type of atom they came from. He was able to conclude that the rays were made of light, particles which were charged negatively as well as a building block of atoms. -
Milikan discovers electrons Charge
Robert Milikan was conductiong an oil drop experiment in 1908 when he first discovered the charge of an electron.He used the oil drop experiment to measure the charge of an electron as well as the electrons mass, and Avogadro's number. for his work he won the Nobel Prize in 1923 for his work in physics. -
Rutherford discovers Nucleus
Ernest Rutherford was a British physicist who discovered the nucleus in 1910, thus disproving the "Plum Pudding Model", by showing that it was a positive center of the atom, not just empty space. He first proved this using the gold foil experiment. -
Neils Bohr Quantum theory
Neils Bohr was the first person to apply Quantum theory to Rutherfords discoveries in 1922. He assumed that electrons travelled in stationary orbits defined by their angular momentum. -
Chadwick discovers Nucleus
In 1932 James Chadwick became responsible for discovering the Neutron after he suggested that in fact the new radiation consisted of uncharged particles of approximately the mass of the proton, and he performed a series of experiments verifying his suggestion, confirming his discovery of the neutron. -
Quantum model
Today we use the most up to date model of the atom called the Quantum model, it represents the atoms stability and is similar to Bohrs model where the electrons surround the nucleus, but the protons and neutrons are in the center of the nucleus, It is the most accurate model of the Atom as far as we know.
