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510
Democritus
Democritus (ca. 460 BC – ca. 370 BC) was an Ancient Greek philosopher. He was an influential pre-Socratic philosopher and pupil of Leucippus, who formulated an atomic theory for the cosmos. Though only a few fragments of his work survive, he was apparently the first to describe invisible "atoms" as the basis of all matter. His atoms — indestructible, uniform, and differing only in size, shape, and motion — anticipated with surprisingaccuracy those discovered by 20th-century scientists. -
Feb 2, 1000
Medieval Alchemy
Alchemy
Goals:
-To discover the relationship of man to the cosmos and take advantage of that relationship to the betterment of mankind.
-To find the "philosopher's stone," an elusive substance that was believed to make possible the creation of an elixir of immortality and the transmutation of common substances into gold.
-In the later Middle Ages, to use alchemy as a tool in the advancement of medicine (as Paracelsus did). -
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John Dalton
John Daltons was an English chemist, meteorologist and physicist. He is best known for his pioneering work in the development of modern atomic theory, and his research into colour blindness. -
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Henri Becquerel
Henri Becquerel French physicist, and the discoverer of radioactivity along with Marie Curie and Pierre Curie, for which all three won the 1903 Nobel Prize in Physics.
- 1896, while investigating phosphorescence in uranium salts, Becquerel accidentally discovered radioactivity.
- He wrapped a fluorescent substance, potassium uranyl sulfate, in photographic platesand black material in preparation for an experiment requiring bright sunlight. Led him to investigate the spontaneous emission of nuclear radiation. -
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Niels Bohr
Niels Bohr During his life timeBohr mentored and collaborated with many of the top physicists of the century at his institute in Copenhagen. He was also part of a team of physicists working on the Manhattan Project during the ColdWar.Bohr published his model of atomic structure, introducing the theory of electrons traveling received the Nobel Prize in Physics for contributions to understanding atomic structure and quantum mechanics. -
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J.J Thomson
J.J ThomsonBritish physicist and Nobel laureate
-credited for the discovery of the electron and of isotopes, and the invention of the mass spectrometer
-1906 Nobel Prize in Physics for the discovery of the electron and for his work on the conduction of electricity in gases.
-1897 the first to propose that the fundamental unit was over 1000 times smaller than an atom, suggesting the sub-atomic particles now known as electrons -
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Ernest Rutherford
Ernest RutherfordBorn in New Zealand, studied under J. J. Thomson at the Cavendish Laboratory in England
-developed Bacquerel's discovery of Radioactivity into an exact and proof that the atoms of the heavier elements, disintegrate into various forms of radiation.
-first to establish the theory of the nuclear atom and to carry out a transmutation reaction. Uranium emanations were shown to consist alpha, beta, and gamma, of exceedingly short wavelength and great energy. -
Marie and Pierre Curie
Marie and Pierre Curie-1894, Marie met the French chemist Pierre Curie
- spent much of their careers studying radioactivity (a term coined by Marie), examining the particles and energy produced as radioactive atoms decayed, and in the process learned about the building blocks of matter.
- established that the heavy element thorium was radioactive and discovered two new elements: polonium and radium. Marie won Nobel Prizes in both physics and chemistry for their work. (Pierre was dead by then) -
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Sir James Chadwick
Sir James ChadwickEnglish physicist
- 1932, discovered a previously unknown particle in the atomic nucleus.the neutronbecause of its lack of electric charge.
- The discovery was crucial for the fission of uranium 235. Uneutrons do not need to overcome any Coulomb barrier where as positively charged alpha particles are repelled and can therefore penetrate and split the nuclei of even the heaviest elements
awarded the Hughes Medal of the Royal Society 1932 and the Nobel Prize for Physics 1935
