History of the Atom and Atomic Model

  • 370

    Democritus and the Atom

    Suggested the existance of atoms in all matter without any scientific explanation. His model was just a circle.
  • Period: 400 to

    Evolution of the Atom

  • Isaac Newton and the Atom

    Agreed with Democritus about the atom being a circle and added that there were forces of some kind that held the atoms together.
  • John Dalton and the Atom

    John said the atom looked like a small circle and formed Dalton's Atomic theory. This theory said all matter is composed of atoms,atoms cannot be made or destroyed,all atoms of the same element are identical,different elements have different types of atoms,chemical reactions occur when atoms are rearranged,compounds are formed from atoms of the constituent elements.
  • Dmitri Mendeleev and the Atom

    Dmitri created the first periodic table and organized the elements by atomic weight. Also thought atom looked like a circle.
  • JJ Thomson and the Atom

    He discovered the electron with a cathode ray tube. With his discovery of the electron, he made the "Plum Pudding Model". It had negative particles mixed within a goop with a positive charge.
  • Ernest Rutherford and the Atom

    He did an experiment in which he shot alpha particles through gold foil, but one of the particles,unexpectedly, bounced back. This showed that there was a hard nucleus that contained a lot of mass. He then hypothisized that the core was made of protons(positively charged), meaning that the protons were the thing that was so massive. His model shows a tiny core of protons with electrons orbiting around the core.
  • Plank and the Atom

    He came up with the idea that if atoms vibrate hard enough you can measure their energy(in quanta). In his model a ring goes around the center of the atom and has electrons on the ring revolving around the nucleus.
  • Niels Bohr and the Atom

    Found that electrons orbiting nucleus are on different "energy levels".
  • Albert Einstein and the Atom

    He formed the atomic power formula of e=mc^2 and had the same atomic model as Bohr.
  • Millikan and the Atom

    Preformed an "oil drop" experiment and found the mass and charge of the electron. He found that the mass was 1/2000 of the mass of a proton and he found that an electron has a negative charge. He used Bohr''s model.
  • Schrodinger and the Atom

    Schrodinger found that electrons do not orbit on neat rings but could be anywhere within a certain cloud. This is the most accurate and up- to- date model and it's called the "cloud model".
  • Chadwick and the Atom

    He discovered the neutron and created a new model. Although the cloud model is more correct than this model, this model is easier to understand and is often taught in science classes.