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Atomic Theory Timeline

  • Democritus
    400 BCE

    Democritus

    He used reasoning instead of science when coming up with his theory. He was the first to suggest that materials were made up of smaller things. He called these things "atomos" and theorized every material has its own type of "atomos". He thought no matter how small you cut things up it would always have the same properties. He thought they couldn't be created or destroyed either. He thought if you could smell something then little particles of it were in the air.
  • Aristotle
    300 BCE

    Aristotle

    Aristotle was a philosopher not a scientist. He disagreed with Democritus' theory and believed everything was made up of earth, fire water, and wind. He had a theory that mass of incomprehensible size was everywhere. This was called "hyle". He also thought there were no separate particles they were all one.
  • George Bauer
    1494

    George Bauer

    He is considered the Founder of Geology. He made a way for a study or systematic for the earth, minerals, and fossils. He made fundamental contributions to mining geology, mineralogy, structural geology, and paleontology.
  • Robert Boyle

    Robert Boyle

    He mainly studied gases. He discussed the possibility of atoms existing. He attempted turning regular metals into gold. He made gas chambers to study from. He did physical experiments unlike greek philosophers. He proposed that elements are composed of "corpuscles" of various types and sizes and can organize themselves into different chemical substances. He distinguished the difference between a mixture to a compound. He is sometimes called the Father of Chemistry.
  • Antoine Lavoisier

    Antoine Lavoisier

    He was known for his experimentation skills. One of his favorite experiments was turning HgO into Hg+O. He used this to come up with the Law of Conservation. He also hinted at the rearrangement of matter in reactions. Matter rearranged, but never disappeared.
  • Amedeo Avogadro

    Amedeo Avogadro

    He is best known for his theory that equal volumes of different gases contain the same number of molecules and are the same temperature. It is now called Amedeo Avogadro's Law.
  • Jpseph Gay-Lussac

    Jpseph Gay-Lussac

    He proposed two fundamental laws of gases in the 19th century. He experimented with gases from balloons.
  • Joseph Proust

    Joseph Proust

    He stated the Law of Definate Proportions. The law states that the ratio of elements in a compound is always the same/constant. He also hinted at the 'lego'ness of matter. He believed that matter could be put together in certain patterns to make bigger, different, and unique matter.
  • John Dalton

    John Dalton

    He did a ton of library research. He looked at almost every scientist related to the atomic theory. His theory contained 6 parts: matter is composed of extremely small particles, atoms are indivisible and indestructible, atoms of a given element are identical in size, mass, and chemical properties, atoms of specific elements are different than those of other elements, and in a chemical reaction, atoms separate, combine and/or rearrange.
  • Henri Becquerel

    Henri Becquerel

    He worked with light coming off of crystals. He discovered radioactivity. He worked with X-rays and electromagnetic fields.
  • Max Planck

    Max Planck

    He created the quantum theory. He worked with hot glowing matter. Albert Einstein used these findings to help him.
  • Robert Millikan

    Robert Millikan

    He figured out the charge of an electron. He proved that quantity was constant for all electrons. He also has a law of motion.
  • Erwin Schrodinger

    Erwin Schrodinger

    He studied color and mechanics. He discovered the wave equation. He published many papers on his thinking.
  • Louis de Broglie

    Louis de Broglie

    He mainly worked with mechanics. He worked with an electron theory, theory of light, and nuclear physics.
  • J.J. Thomson

    J.J. Thomson

    He created the cathode ray. He tested the polarity of atoms with this ray. He figured they were almost all negative. He determined to change the mass and thought of atoms as plum pudding.
  • Werner Heisenberg

    Werner Heisenberg

    He is associated with the theory of quantum mechanics and was captured by germans.
  • Ernest Rutherford

    Ernest Rutherford

    He made two major contributions. Alpha particles are are positive, beta particles are negative, and neutral particles are light. He created the gold foil experiment. He shot atoms through the foil and sometimes it would go different directions. He also found out that the atom has a nucleus.
  • Niels Bohr

    Niels Bohr

    He studied the structure of an atom. He suggested that electrons didn't spiral into the nucleus, but orbit in different levels. This is called the bohr model. The more energy an atom gives off, the closer it is to the nucleus, the more it absorbs, the farther away.