The discovery of the atom

By Avengers123
  • 600 BCE

    Thales of Miletus

    Around 600 B.C. Miletus discovered that a piece of amber, after rubbing it with fur, extracts little pieces of hair. Miletus suggested the force came from amber, little did he know it was connected with any atomic particle.
  • 460 BCE

    Deomocritus

    Not until around 460 B.C Democritus develops the idea of atoms. He asked one question: If you break a piece of matter in half, and then break it in half again, how many breaks will you have to make before you can break it no further? Democritus thought that it ended at some point, a smallest possible bit of matter. He called these basic matter particles, atoms.

  • John Dalton

    In the 1800's John Dalton performed experiments with various chemicals that showed that matter, indeed, seem to consist of elementary lumpy particles atoms. Although he did not know about their structure, he knew that the evidence pointed to something fundamental.

  • J.J Thomson

    In 1897, the English physicist J.J. Thomson discovered the electron and proposed a model for the structure of the atom. Thomson knew that electrons had a negative charge and thought that matter must have a positive charge. He observed raisins stuck on the surface of a lump of pudding.

  • Max Planck

    In the 1900's Max Planck, a professor of theoretical physics showed that when you vibrate atoms strong enough, such as when you heat an object until it glows, you can measure the energy only in discrete units. He called the energy packets quanta.

  • Albert Einstein

    According to Albert Einstein he thought that the quanta behaved like discrete particles.Physicists call Einstein's discrete light particle, a photon. Albert Einstein wrote a ground-breaking paper that explained that light absorption can release electrons from atoms, a phenomenon called the "photoelectric effect." Einstein received his only Nobel Prize for physics in 1921 for his work on the photoelectric effect.

  • Ernest Rutherford

    In 1911 Ernest Rutherford thought it would prove interesting to bombard atoms with these alpha rays, figuring that this experiment could investigate the inside of the atom. He used Radium as the source of the alpha particles and shinned them onto the atoms in gold foil. Behind the foil sat a fluorescent screen for which he could observe the alpha particles impact.

  • Niels Bohr

    In 1912 a Danish physicist, Niels Bohr came up with a theory that said the electrons do not spiral into the nucleus and came up with some rules for what does happen. This had begun a new approach to science because for the first time rules had to fit the observation regardless of how they conflicted with the theories of the time.

  • Wolfgang Pauli

    In 1924 an Austrian physicist, Wolfgang Pauli predicted that an electron should spin while it orbits around the nucleus. The electron can spin in either of two direction. This spin consisted of a fourth quantum number: electron spins.

  • Louis de Broglie

    In 1924 a Frenchman named Louis de Broglie thought about particles of matter. He thought that if light can exist as both particles and waves, why couldn't atom particles also behave like waves? In a few equations derived from Einstein's famous equation, (E=mc2) he showed what matter waves would behave like if they existed at all.

  • Erwin Schrödinger

    In 1926 the Austrian physicist, Erwin Schrödinger had an interesting idea: Why not go all the way with particle waves and try to form a model of the atom on that basis? His theory worked kind of like harmonic theory for a violin string except that the vibrations traveled in circles.The world of the atom, indeed, began to appear very strange. It proved difficult to form an accurate picture of an atom because nothing in our world really compares with it.

  • Max Born

    In 1926, a German physicist, Max Born had an idea about 'psi'. Born thought they resembled waves of chance. These ripples moved along waves of chance, made up of places where particles may occur and places where no particles occurred.

  • Heisenberg

    In 1927 Heisenberg formulated an idea, which agreed with tests, that no experiment can measure the position and momentum of a quantum particle simultaneously. Scientists call this the "Heisenberg uncertainty principle." This implies that as one measures the certainty of the position of a particle, the uncertainty in the momentum gets correspondingly larger.

  • James Chadwick

    In 1932 English physicist James Chadwick finally discover the neutron. He found it to measure slightly heavier than the proton with a mass of 1840 electrons and with no charge, neutral. The proton-neutron together, received the name, "nucleon."

  • Hideki Yukawa

    In 1935 a Japanese physicist, Hideki Yukawa, suggested that exchange forces might also describe the strong force between nucleons. However, virtual photons did not have enough strength for this force, so he thought that there must exist a new kind of virtual particle. Yukawa used Heisenberg's uncertainty principle to explain that a virtual particle could exist for an extremely small fraction of a second

  • Cecil F. Powell

    In 1947, the physicist Cecil F. Powell detected this particle and called it the "pion."Although the pions describe the transmitters of the strong force, they do not get classed with the other force-transmitting particles, such as the photon or the W and Z particles. Pions now appear not as elementary particles but rather composites made up of "quarks."

  • Murray Gell-Mann and Yuval Ne'man

    In 1960, Murray Gell-Mann and Yuval Ne'man independently proposed a method for classifying all the particles then known. The method became known as the Eightfold Way. What the periodic table did for the elements, the Eightfold Way did for the particles.

  • Present

    The year we are currently in...