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600 BCE
Thales of Miletus
He found out that a piece of amber after rubbing it with fur attracts light objects but Thales did not connect the force with any atomic particle -
460 BCE
Greek philosopher Democritus
He developed the idea of atoms when you break a piece of matter in half how much more can you break it before you can break it no more -
English chemist John Dalton
He did various experiments with chemicals that showed that matter consists of atoms -
English physicist J.J. Thomson
He discovered the the electron and proposed a model for the structure of the atom he knew that electrons have a negative charge and presumed that matter has a positive charge his model looked like raisins stuck on the surface of pudding -
A professor of theoretical physics Max Planck
He showed that if you vibrate atoms strong enough you can measure the energy in discrete units he called the energy packs quanta -
Ernest Rutherford
He bombarded atoms with alpha rays so he could investigate the inside of an atom he used radium as the source of the alpha particles and shinned them onto the atoms in gold foil behind the foil was a fluorescent screen so he could observe them -
A Danish physicist, Niels Bohr
He came up with a theory that the electrons do not spiral into the nucleus he came up with two rules 1) electrons can orbit only at certain allowed distances from the nucleus 2)atoms radiate energy when an electron jumps from a higher-energy orbit to a lower-energy orbit also, an atom absorbs energy when an electron gets boosted from a low-energy orbit to a high-energy orbit -
Bohr and a German physicist, Arnold Sommerfeld
They expanded the original Bohr model that electrons travel in certain orbits and the orbits have different shapes and the orbits can tilt in the presence of a magnetic field -
Austrian physicist, Wolfgang Pauli
He predicted that an electron spins around the nucleus the electron can spin either direction if an electron has a certain set of quantum numbers, then no other electron in that atom can have the same set of quantum numbers -
Frenchman Louis de Broglie
He thought about particles of matter since light exists as both particles and rays why couldn't atoms behave like waves with a few equations derived from Einstein's famous equation he showed what matter waves would behave like -
Austrian physicist, Erwin Schrödinger
His idea use particle waves and make a model of the atom on that basis 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 Schrödinger's wave mechanics did not question the makeup of the waves but he had to call it something so he gave it a symbol psi -
German physicist, Max Born
His idea about psi thought they resembled waves of chance the waves of chance ripple around in circles -
History of atoms