AtomicTimeline.EdmundJones

By: Edmund Jones and Max Weinreb ** Ancient art practice especially in the Middle Ages, devoted chiefly to discovering a substance that would transmute the more common metals into gold or silver, and to finding a means of indefinitely prolonging human life. Although its purposes and techniques were often illusory, alchemy was in many ways the predecessor of modern science, especially chemistry.  Postulated the theory of atoms and void; the universe is made up of empty space and a nearly infinite number or invisible particles differing in arrangement, form, and position. He stated that all all matter is composed of indivisible atoms. 
 * Atomic Timeline
 * Alchemists - 500 BC-1720 **
 * Democritus - 442 BC **

Developed methods for the gathering of scientific fact. His work provided the basis for scientific work more than a millenium.  A French chemist who proved the conservation of matter and explained the mysteries of fire.  ** Coulomb - 1780's ** Formed Coulomb's Law: the force one timy charged object exerts on a second one is proportional to the amount of charge on one times the amount of charge on the others and inversely proportional to the square of the distance between them. F=Q1*Q2/r² English chemist who proposed the Atomic Theory which stated that all matter was composed of small indivisible particles called atoms. These atoms possess unique characteristics and weight for different elembets. He also stated that three types of atoms exist: simple (elements), compound (simple molecules), and complex (complex mole  cules). 
 * Aristotle - 384-322 BC **
 * Lavoisier - 1777 **
 * John Dalton - 1803**

Developed the Crookes tube and in it produced cathode rays for the first time. He also invented the radiometer and spinthariscope.  On November 8th, 1895, German scientist Wilhelm Roentgen was conducting experiments in his laboratory on the effects of cathode rays. Specifically he was observing the effect of passing an electrical discharge through gases at a low pressure. While doing so, Roentgen noticed something that earlier studies had not picked up. While passing current through the cathode ray, rays were given off that passed through every day materials such as wood, paper and aluminium. Roentgen further observed that a surface that he had coated with barium platinocyanide and which was placed outside of the cathode discharge tube would give off light despite the fact that it was hidden from the light of the discharge. The conclusions that Roentgen came to were ground breaking: a previously unknown type of radiation had passed through the air and lit up the screen. Discovered x-rays
 * Crookes - 1870's **
 * W.K. Roentgen - 1895 **

A French physicist who found that rays coming from a uranium ore affected a photographic plate like X-rays did. The rays were not from an external source and were more powerful than those from a sample of pure uranium. His experiment led to the discovery of natural radioactivity. 
 * Becquerel - 1896 **

Studied and identified radioactive elements.  In 1903, she won her first Nobel Prize along with her husband Pierre Curie for their study on the spontaneous radiations of the element discovered by another scientist named Becquerel. In 1911, she was awarded the second Nobel Prize in Chemistry to honor her work in the field of radioactivity. In 1932, she founded a Radium institute in Warsaw. It is now popularly known as Maria Skłodowska-Curie Institute of Oncology First to measure the electron. Developed the plum-pudding model of the atom. Describes the atom as a slightly positive sphere with small electrons inside.  Stated that radiation is quantized.  ** Albert Einstein - 1905 ** Proposed the quantum of light in which he states that light behaves like a particle but also has a wave nature, giving it a dual nature. Stated the equivalence of energy and mass through the theory of special relativity.  ** Robert Millikan - 1908-1917 ** Discovered the charge of an electron with his oil drop experiment. 
 * The Curies - 1898 **
 * J.J. Thomson - 1898 **
 * Max Planck - 1900 **

Inferred a small, dense, positively-charged nucleus as the result of the alpha particle scattering gold foil experiment.  A Danish physicist who stated that electrons could only orbit the nucleus in succesively larger orbits around the nucleus. The outer orbits could hold more electrons. The electrons in the outermost shell determine the properties of the atom. He also inferred that when an electron moves from an outer orbit to an inner orbit it emits a quantum of energy, a photon, in the form of light. 
 * Ernest Rutherford - 1909-1911 **
 * Neils Bohr - 1913 **

Demonstrated that energy and mass are conserved in atomic processes.  ** Erwin Schroedinger - 1926 ** Developed wave mechanics which describe the behavior of quantum systems for bosons.  ** Chadwick - 1931 ** Discovered the neutron.  ** Otto Hahn - 1938 ** Found that when Uranium is bombarded by neutrons it produces smaller nuclei roughly half the size of the original Uranium nucleus.  ** Lise Meitner - 1938 ** Realized that Hahn was splitting the Uranium nucleus, something never done before.  ** Glen Seaborg - 1951 ** Succeeded in making man-made elements.  **Murray Gell-Mann and George Zweig - 1964 **  
 * Geiger - 1925 **



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