1 / 14

History of the Atom

History of the Atom. Democritus of Abdera. Democritus: 460-370 BCE Greek mathematician and philosopher Co-author (with Leucippus) of the idea that all matter made of small parts atoma Proposed that the behaviour of substances was due to the type of atom. Aristotle.

eagan-kaufman
Download Presentation

History of the Atom

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. History of the Atom

  2. Democritus of Abdera • Democritus: 460-370 BCE • Greek mathematician and philosopher • Co-author (with Leucippus) of the idea that all matter made of small parts • atoma • Proposed that the behaviour of substances was due to the type of atom

  3. Aristotle • Greek Philosopher: 384-322 BCE • Not an ‘atomist’ • Proposed all matter made up of 5 elements: • Fire • Air • Water • Earth • Aether

  4. Robert Boyle • Robert Boyle: 1627-1691 • Performed experiments with controls and published detailed results • 1661: Published claiming that Aristotle's ideas were incorrect • Some 'elements' (like mercury) did not contain the Greek elements (earth, air, fire, water)

  5. John Dalton • Dalton: 1766-1844 • Law of Multiple Proportions (1803): elements combine in mass ratios of small whole numbers. • Small whole numbers reflect the atoms involved, therefore there are atoms • Atomic theory contains 4 hypotheses

  6. Dalton’s Atomic Theory • Elements are made of small particles called atoms. (Dalton viewed atoms as small spheres of differing characteristics.) • All atoms of an element are identical. All atoms of one element are different from atoms of other elements. • Compounds are made of atoms of more than one element. The ratio of the elements is a simple fraction. • A chemical reaction involves separation, combination or rearrangement of atoms.

  7. Joseph John Thomson • 1856-1940 • Used a cathode ray tube to determine the presence of electrons 1897 • Suggested the plum pudding model of the atom and the existence of isotopes • Won the Nobel Prize in Physics in 1906

  8. Robert A. Millikan • 1858-1953 • Used the 'falling drop method' to determine the charge of the electron (-1.6022 x 10-19 C) and mass of electron as 9.10 x 10-28 g • Investigated photoelectric effect and spectroscopy of elements • Won the Nobel Prize in Physics in 1923

  9. Marie Curie • 1867-1934 • Worked with husband Pierre to study radioactivity • Isolated elements polonium and radium • Shared Nobel Prize in Physics 1903, won Nobel Prize in Chemistry 1911 for work with radioactive elements.

  10. Ernest Rutherford • 1871-1937 • Investigated release and measurement of different forms of radiation from elements (α, β, γ) • Gold foil experiment with Geiger and Marsden led to new model of an atom • Model:ruther14.swf • Nobel Prize in Chemistry 1908

  11. Model of the atom in the early 1900s • Nucleus: has positive charge, very small, but very dense • Proton: same charge as electron, but opposite. Mass=1.67262 x 10-24 g • Vast empty space around nucleus contains electrons

  12. Where are the electrons? • Niels Bohr: 1885-1962 • Collaborated with Rutherford • Used emission spectra to propose Bohr model of atom 1913 • Electrons found in specific ‘orbits’ around nucleus • Most of atom is empty space • Nobel Prize Physics 1922

  13. James Chadwick • 1891-1974 • Discovered the neutron and worked on fission of atoms • Discovery of neutron (mass = 1.67493 x 10-24 g) explained the mass problem of many atoms • Nobel Prize in Physics 1935

  14. Current Model • Based on the previous work, as well as Einstein, Heisenberg, Born, Schrödinger and others • Nucleus contains p+ and no • Made of smaller particles called quarks • uud, ddu (baryons) • Electron cloud • e- are in areas of probability, predicted by wave equations • leptons

More Related