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• Elements are made up of neutrons, protons and electrons
• The early elements that existed were H and He
• Early in the Big Bang

  1. Tiny elementary particle

  2. Universe expanded and cooled

  3. Proton-proton chain reaction forming Helium

  4. Universe ran into a problem, could not synthesize additional elements
• Singularity


  A one-dimensional point which contains a huge mass in an infinitely small space, where density and gravity become infinite and space-time curves infinitely, and where the laws of physics as we know them cease to operate
• Inflation


  The basic homogeneity in distribution of matter in the universe was established as a consequence of the first phase
• Nucleosynthesis


  The nuclear fusion and the formation of new nuclei actions in the early stages of development of the universe
• Recombination


  The formation of the capture of free electrons by the cations in a plasma
• Dmitri Mendeleev


  Created a classification of elements based on their atomic weight, demonstrating a periodic pattern of physical and chemical properties
• Henry Moseley


  Demonstrated that the major properties of an element are determined by the atomic number, not by the atomic weight, and firmly established the relationship between atomic number and the charge of the atomic nucleus
• Henry Moseley's experiment


  1. Shooting electrons at elements caused them to release x-rays at unique frequencies

  2. Frequency increased by a certain amount when the "positive charge" of the chosen element was higher

  3. Arranging elements according to the square root of the frequency they emitted allowed for a better arrangement of the periodic table and predicted elements not yet discovered

  4. His method of identifying elements by shooting electrons and looking at x-rays became a very useful tool in characterizing elements, now called x-ray spectroscopy
• 1. ray spectroscopy


  A method of identifying elements by shooting electrons and looking at x-rays
• Moseley's results showed that the frequency of the X-rays given off by an element was mathematically related to the position of that element in the Periodic table, and was proportional to the charge of the nucleus, or the atomic number
• There were four gaps in the periodic table corresponding to atomic numbers 43, 61, 85, and 87, which were later synthesized in the laboratory through nuclear transmutations
• Nuclear transmutation


  A reaction involving the transformation of one element or isotope into another element
• Ernest Rutherford successfully carried out the first nuclear transmutation reaction, creating an isotope of oxygen 17O


  1919
• Neutrons (neutral particles) are often used to bombard atomic nuclei in particle accelerators, instead of using fast-moving alpha particles, to synthesize new elements
• James Chadwick discovered the neutron


  1932
• Emilio Segre and Carlo Perrier created the first element not found naturally on Earth, technetium, by bombarding molybdenum with deuterons


  1937
• The first controlled nuclear chain reaction was carried out in a reactor at the University of Chicago


  1942
• Particle accelerators are used to synthesize new elements by speeding up protons to overcome the repulsion between the protons and the target atomic nuclei using magnetic and electrical fields
• Ernest Lawrence synthesized element 43, technetium, using a linear particle accelerator by bombarding molybdenum with fast-moving neutrons


  1937
• Dale Corson, K. Mackenzie, and Emilio Segre discovered element 85, astatine, by bombarding bismuth with fast-moving alpha particles in a cyclotron


  1940
• Elements 61 (promethium) and 87 (francium) were discovered through studies in radioactivity as decay products of uranium