History of Atomic Theory

By ThomasRaeburn
  • 500 BCE

    The Alchemists

    The Alchemists were based on the belief that everything in the universe was created by four elements and the ideas proposed by the ancient greeks. The four elements they believed made up the world were water, fire, air, and earth.
  • 400 BCE

    Ancient Greeks

    The estimated time where the ancient greeks made most of their discoveries is not agreed on by everyone but it is said that they made most of their findings around 400 BCE. The Ancient Greeks discovered that everything in the world is made up of these tiny things called atoms and also proposed the idea that everything is made up of the four elements.

  • John Dalton

    John Dalton claimed that all the atoms in elements were identical, but depending on the element presented the atoms could vary in size and mass.

  • J.J Thomson

    Thomson discovered that all atoms contained little negatively charged particles and electrons. Thomson was also the one who created the plum pudding model. Most of his discoveries were made around 1897

  • Hantaro Nagaoka

    Hantaro is most commonly known for his "Saturnian" system in 1904

  • Ernest Rutherford

    Rutherford found out in 1907 that some substances have half-lives Rutherford also found a flaw in Thomson's model back in 1911. He figured out that the atom had a small but heavy nucleus. After Rutherford found this out he created a new model and names it the "Rutherford model"

  • Niels Bohr

    Around the time 1913 Bohr gave a theory that electrons should be moving around the nucleus but not freely, in a certain orbit. Going from a higher energy orbit to a lower one. Bohr also created a new model to show the shells and orbit of the elections

  • Max Planck

    Planck was a German physicist who was the originator of the quantum theory. Which is a theory that helped old chemists and physicists understand more about the atomic and subatomic process'

  • Francis William Aston

    Aston is known currently for his major discovery of isotopes, which are molecules that have the same formula but have a different structure. He found this by the use of a mass spectrograph.

  • Albert Einstein

    Einstein probably had one of the biggest contributions to the atomic theory by proposing the idea of gravitation. He also proposed the general theory of relativity. It is said he made most of his discoveries between the years of 1916 and 1921

  • Erwin Schrödinger

    Around 1926 Schrödinger took Bohr's model one step further by using his knowledge in math to determine an equation to describe the location of an electron in a certain position.

  • Satyendra Nath Bose

    Bose is known for his work on quantum mechanics which was the foundation for the Bose-Einstein statistics

  • Werner Heisenberg

    The greatest contribution that Heisenberg had to the atomic theory was that he discovered that there is no way of knowing the position and momentum of a particle at the same time.

  • Wolfgang Pauli

    Pauli discovered in the Bohr model that no two electrons in an atom could have the same set of quantum numbers and created his own principal called the "Pauli Principal"

  • Louis De Broglie

    Louis De Broglie figured out how the wave nature of elections work and he also proposed the idea that all matter has wave properties

  • James Chadwick

    Chadwick discovered that atoms had something else in the center of it called neutrons. He figured out that neutrons didn't have a positive or negative charge but still contributed to the weight of the atom as much as protons did.

  • Dorothy Crowfoot Hodgkin

    Hodgkin figured out the molecular structure of penicillin, insulin, and vitamin B12.

  • Rosalind Franklin

    Rosalind Franklin discovered the molecular structure of coal and carbon which were later used to develop strong carbon fibers and more. She also discovered molecular structures of DNA, RNA, and Virus' which gave important information that we use to this day.

  • Enrico Fermi

    Fermi is most commonly known for his experiments in the first-ever chain reaction. He did this by releasing energy from the nucleus of the atoms.

  • Robert J. Leroy

    Leroy was famous for the development of the Leroy-Bernstein Theory. He was also interested in the intramolecular forces, he defined and analyzed the basic forces between atoms and molecules.

  • Richard Bader

    Bader discovered how important the electron density really is for explaining how the behavior of atoms works.