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The history of an atom Timeline

The history of an atom Timeline. By: Angelica Mena. Democritus-460 BC.

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The history of an atom Timeline

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  1. The history of an atom Timeline By: Angelica Mena

  2. Democritus-460 BC Democritus was an ancient Greek philosopher born in Greece. In his atomic hypothesis he claimed that there are two elements of life: atoms and the void in which they exist and move. He thought that atoms were indivisible, indestructible, and in motion. He also found that atoms were infinite in number.

  3. Dalton-1803 • John Dalton was an English chemist, meteorologist, and physicist. He discovered the atomic theory in 1803. His theory insisted that matter is composed of atoms, all atoms of the same elements are identical. Atoms cannot be made or destroyed. Chemical reactions occur when atoms are rearranged. There are three types of atoms simple, compound and complex.

  4. Dmitri Mendeleev- 1869 • Dmitri Mendeleev, a Russian chemist and inventor who created the first version of the periodic table of elements. He laid out the element from lightest to heaviest and that’s when he realized their were gaps in the table. He predicted that some properties of elements were yet to be discovered but, already existed.

  5. Dmitri Mendeleev’s Periodic Table

  6. Eugene Goldstein-1885 Eugene Goldstein was a German physicist who, coined the term cathode rays for negatively charge electrons. He also discovered anode rays , the positively-charged particles formed when electrons are removed from the gas particles in a cathode-ray tube. He showed that cathode rays can cast shadows, then demonstrated how such rays are emitted, perpendicular to the cathode surface, and can be influenced with magnetic fields.

  7. Henri Becquerel- 1896 Henri Becquerel was a French physicist, who discovered radioactivity, by accident. He was unable to perform an experiment that he needed sunlight for because it was raining. He wrapped his fluorescing crystals  in a black cloth, along with the photographic plate and a copper Maltese cross, and waited for a sunnier day. A few days later, he unwrapped the crystals and found of that they were emitting radiation because they were never exposed to sunlight.

  8. J.J. Thomson-1897 J.J. Thomson was a British physicist discovered the electron in 1897 through his experiments on the properties of cathode rays. His experiments suggested not only that cathode rays were over 1000 times lighter than the hydrogen atom, but also that their mass was the same whatever type of atom they came from. He also created the plum pudding model in which he said, “the electrons were embedded in the positive charge like plums in pudding.”

  9. Ernest Rutherford- 1907 Ernest Rutherford was a British chemist and physicist who later became known as the father of nuclear physics. He determined the structure of an atom and changed nitrogen to oxygen by splitting the atom’s nucleus. Also he discovered and named the nucleus and protons.

  10. Millikan-1910 Robert Millikan was an American born experimental physicist. In 1910, he discovered the charge of the electron using his oil drop experiment. His experiment was based on Thomson’s but, he substituted oil instead of water. With this experiment, he was able to precisely measure the charge of an electron. When combined with the charge to mass ratio, he could then determine the mass of the electron. He was awarded the Nobel Prize in Physics for this experiment.

  11. Niels Bohr -1913 Niels Bohr was a Danish physicist. In 1913 he introduced his own model of a hydrogen atom called the Bohr model. This model showed that electrons orbit a positively-charged nucleus. He also said that the outer orbit could carry more electrons than the inner orbits.

  12. Frederick Soddy-1913 Frederick Soddy was an English radio chemist who proved the existence of isotopes of certain radioactive elements. He said that certain elements exist in two or more forms which have different atomic weights but are still the same element. Isotopes occupy the same place in the Periodic table.

  13. Heisenburg-1925 • Heisenberg along with Max Born and Pascual Jordan created the matrix formulation of quantum mechanics in 1925. This extended the bohr model by describing how the quantum jumps occur. This result happened because the physical properties of particles were interrupted and matrices were created.

  14. Chadwick-1932 James Chadwick was an English Nobel laureate in physics. In 1932 he discovered the existence of neutrons, the third piece of the atom to be found. Neutrons are particles with no charge. This discovery accelerated more findings in atomic physics. The end!

  15. Citations Slide1 Atomic model- http://www.glogster.com/media/1/6/41/7/6410729.gif Slide2 Democritus- http://upload.wikimedia.org/wikipedia/commons/thumb/b/b9/Democritus2.jpg/200px-Democritus2.jpg Slide3 Dalton’s atom model- http://www.kentchemistry.com/images/links/gases/1803_dalton2.jpg Dalton- http://upload.wikimedia.org/wikipedia/commons/thumb/3/3f/Dalton_John_desk.jpg/240px-Dalton_John_desk.jpg Slide4 Dmitri- http://upload.wikimedia.org/wikipedia/commons/thumb/c/c8/DIMendeleevCab.jpg/225px-DIMendeleevCab.jpg slide5 Dmitri periodic table- http://upload.wikimedia.org/wikipedia/commons/thumb/5/55/Mendelejevs_periodiska_system_1871.png/550px-Mendelejevs_periodiska_system_1871.png

  16. Citations(continued) Slide6 Anode rays- http://cdn.dipity.com/uploads/events/408a819c9de9f4b075fe3376a5db007f_1M.png Slide7 Henri- http://www.daviddarling.info/images/Henri_Becquerel.jpg Slide8 Plum pudding model- http://upload.wikimedia.org/wikipedia/commons/thumb/f/ff/Plum_pudding_atom.svg/220px-Plum_pudding_atom.svg.png Slide9 Ernest- http://extranet.kinnick.pac.dodea.edu/teachershtml/scott.andrews/physci/chem/cool_cats11/A1/e_ruther/images/ruther2.jpg Slide10 Millikan- http://www.xtimeline.com/__UserPic_Large/6064/ELT200803021630362239380.JPG Oil drop model- http://upload.wikimedia.org/wikipedia/commons/6/6f/Millikan%E2%80%99s_oil-drop_apparatus_1.jpg

  17. Citations(continued) Slide11 Bohr model- http://upload.wikimedia.org/wikipedia/commons/thumb/5/55/Bohr-atom-PAR.svg/310px-Bohr-atom-PAR.svg.png Slide12 Isotopes- http://1.bp.blogspot.com/-pN5hxFZswQ4/Thjy0KJdPQI/AAAAAAAAAHw/Lu4K8AX9-BQ/s1600/isotopes+of+hydrogen.jpg Slide 13 Heisenberg- http://upload.wikimedia.org/wikipedia/commons/thumb/f/f8/Bundesarchiv_Bild183-R57262,_Werner_Heisenberg.jpg/225px-Bundesarchiv_Bild183-R57262,_Werner_Heisenberg.jpg Slide14 Chadwick- http://upload.wikimedia.org/wikipedia/commons/thumb/c/c2/Chadwick.jpg/162px-Chadwick.jpg

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