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442 BCE
Thinking about Matter
442BC- Democritus came up with the thought that all matter is made up of individual elements. -
John Dalton and atoms
1803- John Dalton decided on a theory that everything is made of atoms of different weights, he also questioned whether atoms where sphere in shape. -
Cathode ray tube
1870- Sir William Crookes created an early model for the Cathode Ray tube, which is high-vacuum tube where cathode rays make a luminous image on a fluorescent screen, nowadays used for TVs. -
Radiation, Energy and the Atom
1898 - Pierre and Marie Curie speculated that radioactive particles cause atoms to break down. -
Discovering Electrons
Joseph John Thomson used his knowledge of cathode rays and their properties to discover the electron. -
Quantum theory early development
1900- Max Planck proposed the quantum theory, which says that electromagnetic energy could only be emitted in quantized form. -
Einstein and the nature of light
1905- Albert Einstein formed generic theories of relativity and saw light as wave and particle. This was the basis of nuclear energy. -
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Charge of an Electron measured
Known as the elementary charge, Robert Millikan measured the charge of a single electron. -
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Development of atom structure
Using the gold foil experiment, Rutherford proposed the theory for the structure of an atom and showed the existence of atomic nucleus. (A atomic nucleus is the small, part made up of of protons and neutrons at the center of an atom. -
Improvement of the atomic model
1913- Neil Bohr created the Bohr Atomic model. While doing so, he incorporated the Planck quantum theory, finding that when electrons change orbits they emit a quantum of various energy. -
Shrödinger describes Electron changes
1926- Erwin Shrödinger developed the Schrodinger equation which illustrates how the quantum state of a system changes with time. -
The Neutron is discovered
1931- James Chadwick discovered the neutron component of the atomic nucleus, which shows the nuclear division of uranium. Because of his findings, it is now possible to establish heavier elements than uranium in a lab. -
Nuclear fission developed
1938- Otto Hahn and Lise Meitner discover nuclear fission. -
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Discoveries of Transuranic elements
1944-1958 - Seaborg identified nine elements – americium (95), curium (96), berkelium (97), californium (98), einsteinium (99), fermium (100), mendelevium (101), and nobelium (102) and Seaborgium. (Alongside his colleagues he found 11 elements, during his career.) -
Development of I-131
1951- Glenn Seaborg developed Iodine 131 for Thyroid disease which is a type of radioactive iodine, as well as many discoveries in Nuclear medicine. -
Particles smaller than the atom
1964- Murray Gell and George Zweig show that elementary particles that have no substructure and therefore can't be split, using the Quark model.
