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460
Democritus
460- 370 BC
Democritus said that everything is made up of atoms. he was an ancient Greek philosopher. He thought that the atoms had empty space inbetween them,are always going to be in constant motion, atoms can not be destroyed, and the amount of atoms are infinite. He also thought the way the element looked physically, connected to the way the atoms are shaped and the way they work. -
Antoine Lavoisier
1743-1794
Helped come up withthe law of conservation.
Law of Conservation- matter cannot be made or destroyed, matter can be rearranged but cannot disappear.
helps understand the rearrangement of matter in chemical reactions. -
John Dalton
1766-1844
john Dalton was one of the first people to suggest the existence of the atom. He gave us the first working model of the atom and help expand the atomic theory to greater understanding. HIs atomic theory was:
1. all matter is composed of atoms
2. all atoms of a given element are identical in properties and mass
3. atoms of different elements differ in properties and size mass
4. a chemical reaction is the rearrangment of atoms. matter can not be created or destroyed -
Max Planck
1858-1947
Planck made the discovery of quantums. he stated that energy cannot be continuous, but instead is carried in tiny discontinuous units. each quantums energy should equal the frequency of radiation multiplied by the universal constant he defined. -
Henri Becquerel
1852-1908
Henri is well known for discovering spontanious radioactivity.
the first thing he did was work with plane-polarised light by magnetic fields. after that, he went to infra red, being able to make observations by light being released from certain phosphorescent crystals. he studied the absorption of light in the crystles. he mainly studied the phosphorescence of uranium compounds in particles. -
Henry Mosely
1887-1915
Henry developed a way to use X-ray spectra to study the atom and how it is structured. He also helped rearrange a more accurate way of setting up the periodic table by the atomic numbers and having them more accurate. -
Marie and Pierre Curie
1859-1934
Marie and Pierre both worked together, then eventually got married. they worked in the study of radioactivity. them working with radioactivity eventually led them to discovering the two elements radium and polonium. Marie made the surprising discovery by uranium pitchblende and chalcolite emitted four times the radiation that would be expected from the uranium substance. therefore she found out this had an unknow radiating element. -
J.J Thomson
Thomson is most known for is making of the atomic model, commonly known as the plum pudding model. this model is called that because the pudding part would be the positve particles of the atom, and the plums in the pudding would be the electrons, which is the negitively charged particles. -
Ernest Rutherford
Rutherford is known for finding out the existence of the nuecleus in the atom. he provided a more detailed picute of the internal structure of the atom. His experiment for discovering this was to shoot a beam of alpha particles through a very thin sheet of gold. he expected the beam of particles to go right through the gold. but insead found out they bounced of of something dense and solid in the middle, which was found out the be the nucleus. -
Niels Bohr
1885-1962
Bohr was a philosopher and a physicist. He was a huge help to further more go into how the atom works and making up a better and more understandable model. his input on the atom was adding energy levels. this allowed the electroms to be on the outside of the nucleus and orbit around it. He also helped develop quantum mechanics which moves elecroms from one energy level to the other, instead of them constantly being continuously. -
Robert Millikan
1868-1953
Robert was an American experimental physicist. he worked on the elementary electronic charge and photoelectric affect. he was rewarded with a nobel prize for his discovery and work on both of these. -
Erwin Schridinger
Erwin helped create a different atomic model. this model is known as the quantum mechanical model for the atom. this sounds alot like Bohrs model, but its not. unlike his, which defines the path the electron is on, it predicts the odds of the location the the electron in the atom. it looks like an "electron cloud". where the cloud looks most dense, that is likely to be where the higher energy of the electrons are. -
James Chadwick
1891-1974
James Chadwick was very important when it came to the atom. He discovered that there are such things as neutrons in the atom.
neutrons are made up of emementary particles that have no charge. in 1935 James won the nobel prize for his discovery of the neutron. -
Werner Heisenberg
1901-1976
Werner was another main person to help discover and create the quantum mechanics. he was also awarded a nobel prize in 1932 for the creation of quantum mechanics. another thing he contributed to was theories for hydrodynamics or tubulent flows, the nucleus of the atom, and subatomic particles -
Aristotle
384-322 BC
Aristotle is another ancient greek philosopher. unlike the others, he didn't agree with the ancient greek theory of atoms being different sizes, being in constant motion or being regular geometric shapes. His theory was that all matter was made up of four elements; water, fire, earth and air. in Aristotles theory, it was thought to have 2 different forces,conflict and harmony.
