Timeline: Structure of the atom

  • 500 BCE

    Early ideas about the atom

    Democritus and his teacher Leucippus were talking. Democritus introduced the atomos (uncuttable). All matter was made of these atomos and were of different sizes and shapes. Iron had hooks, salt was spikey and water was slippery. Around the same time, Aristotle proposed his own idea of the atom. He said different things were made of different amounts of Earth, Fire, Water, Air and Aether.
  • Dalton's model of the atom

    Matter was indivisible and was rearranged to form different compounds. He was the first to attempt a scientific experiment.
  • Plum Pudding Model

    J.J. Thompson discovered atoms have electrons and are much smaller than atoms. J.J. Thompson said it was more like a blueberry plum muffin, with the positive charge as pudding and electrons as the blueberries stuck in the dough.
  • Nuclear model

    Ernest Rutherford discovered that atoms had a positively charged nucleus located in the centre and that atoms were basically empty space.
  • Bohr Model

    Niels Bohr came up with a model that showed electrons in an orbit pattern instead of being randomly distributed. The electrons would orbit the nucleus like planets around the sun in a circular orbit.
  • Quantum Mechanics Model

    Erwin Schrödinger produced a model that showed the electrons as hyperactive flies, buzzing around everywhere, sketching out shapes. If a timelapse of the electron path was made, an orbital would have been made around the atom as the most frequent pattern.
  • Quantum Mechanics Model with Protons + Neutrons

    In 1919, Ernest Rutherford discovered Protons and in 1932, James Chadwick discovered Neutrons. The most correct model shows a grouping of Protons and Neutrons in the centre with orbitals around it.