Melissa's Atomic Theory Timeline

By mdarby1120
  • 470 BCE

    Democritus

    He developed the concept of the 'atom', Greek for 'indivisible'. Democritus believed that everything in the universe was made up of atoms, which were microscopic and indestructible. However, Democritus greatest contribution to modern science was arguably the atomic theory he elucidated. According to Democritus' atomic theory, the universe and all matter obey the following principles: Everything is composed of “atoms”, which are physically, but not geometrically, indivisible.
  • 384 BCE

    Aristotle

    When the Atomic Theory was discovered, Aristotle did not believe in it. He believed that all substances were made of Fire, Water, Air, and Earth. He taught his beliefs, and he was so well known for his teachings, most believed him to be right.

  • Joseph Louis Proust

    contributed to the study of electromagnetism and electrochemistry. His main discoveries include the principles underlying electromagnetic induction, diamagnetism and electrolysis.

  • John Dalton

    In 1803 he revealed the concept of Dalton's Law of Partial Pressures. Dalton's atomic theory proposed that all matter was composed of atoms, indivisible and indestructible building blocks. While all atoms of an element were identical, different elements had atoms of differing size and mass.

  • Michael Faraday

    In 1847 he discovered that the optical properties of gold colloids differed from those of the corresponding bulk metal.

  • Henri Becquerel

    The Discovery of Radioactivity. Henri Becquerel Atomic Theory. Henri Becquerel made an important contribution to our understanding of atomic theory when he discovered the existence of radioactivity. In this lesson, learn about him and his amazing discovery

  • Antoine Lavoisier

    Lavoisier is most noted for his discovery of the role oxygen plays in combustion. He recognized and named oxygen (1778) and hydrogen (1783) and opposed the phlogiston theory. Lavoisier helped construct the metric system, wrote the first extensive list of elements, and helped to reform chemical nomenclature.

  • J.J. Thomson

    In 1897, J.J. Thomson discovered the electron by experimenting with a Crookes, or cathode ray, tube. He demonstrated that cathode rays were negatively charged. In addition, he also studied positively charged particles in neon gas.

  • Marie & Pierre

    they discovered radium and polonium in 1898. For their joint research into radioactivity, Marie and Pierre Curie were awarded the 1903 Nobel Prize in Physics. As a team, the Curies would go on to even greater scientific discoveries. In 1898, they announced the discovery of two new elements, radium and polonium.

  • Albert Einstein

    Einstein treated matter and energy as exchangeable. Albert Einstein became famous for the theory of relativity, which laid the basis for the release of atomicenergy. In 1905 Albert Einstein formulates Special Theory of Relativity. ... He advanced the theory of relativity when he was only 26 years old.

  • Neils Bohr

    Niels Bohr proposed a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities. Electrons should move around the nucleus but only in prescribed orbits. When jumping from one orbit to another with lower energy, a light quantum is emitted.

  • Ernest Rutherford

    responsible for a remarkable series of discoveries in the fields of radioactivity and nuclear physics. He discovered alpha and beta rays, set forth the laws of radioactive decay, and identified alpha particles as helium nuclei. Rutherford overturned Thomson's model in 1911 with his well-known gold foil experiment in which he demonstrated that the atom has a tiny, heavy nucleus.

  • Max Planck

    Max Planck, a German physicist, is best known as the originator of the quantum theory of energy for which he was awarded the Nobel Prize in 1918. His work contributed significantly to the understanding of atomic and subatomic processes.

  • Robert Millikan

    honored with the Nobel Prize for Physics in 1923 for the measurement of the elementary electric charge and for his work on the photoelectric effect.His oil drop experiment helped to quantify the charge of an electron, which contributed greatly to our understanding of the structure of the atom and atomic theory.

  • James Chadwick

    awarded the 1935 Nobel Prize in Physics for his discovery of the neutron in 1932. In 1941, he wrote the final draft of the MAUD Report, which inspired the U.S. government to begin serious atomic bomb research efforts.James Chadwick played a vital role in the atomic theory, as he discovered the Neutron in atoms. Neutrons are located in the center of an atom, in the nucleus along with the protons.