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Timeline of Atomic Theory

  • Acharya Kanad
    600 BCE

    Acharya Kanad

    Kanad was believed to be the first one to have an idea of indestructible particle of matter. This idea came to him when hes was walking around, breaking his food up into smaller pieces.
  • First idea of atoms
    500 BCE

    First idea of atoms

    Leucippus and Democritus purposed to the early community of Greek chemists that matter was made up of different formations of invisible particles called "atomos" make up forms of matter.
  • Crazy Alchemists
    500 BCE

    Crazy Alchemists

    The alchemists contributed to the atomic theory by helping us further develop the modern periodic table.
  • Robert Boyle's discussion

    Robert Boyle's discussion

    Boyle presented a discussion of atoms in his 'The Skeptical Chemist'.
  • John Dalton's first modern Atomic Theory

    John Dalton's first modern Atomic Theory

    Dalton had presented the first modern atomic theory by developing the law of multiple proportions.
  • Thomson's discovery

    Thomson's discovery

    J.J. Thomson discovered that some of the invisible particles were negatively charged, which we would later call electrons.
  • Marie Curie

    Marie Curie

    Curie conducted several experiments on uranium rays and found they stay constant. She theorized that the rays had come from the elements atomic structure. This discovery would go on to be the first step in atomic physics. She also discovered two new elements, radium and polonium.
  • Max Planck

    Max Planck

    Planck was the original creator of the quantum theory. He further developed an understanding of atomic and subatomic processes. He created a constant that helps us describe the behavior of particles and waves at an atomic level.
  • Hantaro Nagaoka

    Hantaro Nagaoka

    Nagaoka proposed an alternative planetary atomic model. The positively charged nucleus is surrounded by rings of negatively charged electrons. Like Saturn's rings.
  • Einstein's Theory

    Einstein's Theory

    Albert Einstein is arguably the most famous physicist. He was responsible for creating the theory of relativity, which would later help with atomic power and the 'Manhattan Project'.
  • Rutherford Diagram

    Rutherford Diagram

    Rutherford created an atom diagram which is very well as it has become the symbol for all sciences. He hypothesized that an atom is made up of empty space mostly with electrons orbiting in a set, predictable paths around fixed, positively charged nucleus.
  • Niels Bohr

    Niels Bohr

    Bohr discovered electrons and radioactivity in the atom which would change the model of the atom. His theory explained why atoms emit light in fixed wavelengths.
  • De Brogile

    De Brogile

    Brogile hypothesized that not only electrons traveled in waves and that matter have wave properties. Which he then used to help develop the theory for quantum mechanics.
  • Werner Heisenberg

    Werner Heisenberg

    Heisenberg helped further modify the atomic theory by formulating quantum mechanics and also discovering the uncertainty principle (neither the position or momentum of a particle can be found at an exact point).
  • Wolfgang Pauli

    Wolfgang Pauli

    Pauli created a principle that states that no two electrons in an atom could have identical sets of quantum numbers.
  • Erwin Schrodinger

    Erwin Schrodinger

    Schrodinger is responsible for creating the "Electron Cloud model" a dense nucleus with a cloud multiple orbitals of electrons surrounding the nucleus.
  • James Chadwick

    James Chadwick

    James Chadwick had a major contribution to the atomic theory by discovering another particle in an atom we know as neutrons. Located with protons in the center of the nucleus with electrons orbiting around it.
  • Gerhard Herzberg

    Gerhard Herzberg

    Herzberg mainly worked on atomic and molecular spectroscopy. He is well known for determining the structure of diatomic and polyatomic molecules.
  • William Giauque

    William Giauque

    Giauque contributed most of his life work to establishing the third law of thermodynamics and invented the adiabatic demagnetization cool- ing technique.
  • Dorothy Hodgkin

    Dorothy Hodgkin

    Hodgkin was able to determine the molecular structure of penicillin, insulin, and vitamin B12. She used x-rays to find out the structure of these biochemical substances.