-
430 BCE
Democritus
He found that atoms are not all the same, they are eternal, and always moving. He made a theory on this to explain why and how atoms were so small, and what they were about. He proposed a more advance atomic theory. -
John Dalton
He proposed the atomic theory. He inferred proportions of elements in compounds. He found the atomic weight, and chemical symbols. He also had the most useful atomic theory of matter. To come up with this, he tested gases and used evaporation to find out what the gases had on that mixture all together. -
Dmitri Mendeleev
Arranged elements into 7 groups with similar properties. He discovered that the properties of elements "were periodic functions of the their atomic weights". This became known as the Periodic Law. -
Eugene Goldstein
In 1886, Goldstein helped contribute to the events that lead to the discovery of the proton. He observed the changes in a cathode ray tube, and discovered the anode rays, positively-charged particles that moved in the opposite direction, from the anode to the cathode -
J.J. Thomson
He found electrons and subatomic particles when he was working with cathode ray tubes. He was working with glass tubes and electricity and messed up and discovered electrons. -
Max Planck
He was the person who came up with the original quantum theory. To come up with this, all he did was research from pervious scientists and a little bit on his own, and then wrote a book on the quantum theory (the theory: the behavior or matter and energy in an atom). He also was looking at color changes from energy. He also made a math equation to help with this theory. -
Robert Millikan
He was by far the most famous American scientist. He wanted to find the electrical charge of electrons. He measured water droplets, and that wasn’t successful, so he measured oil droplets, where all this proved electrons were negatively charged. -
Ernest Rutherford
He proved J.J Thomson's atomic model to be incorrect. He ionized gas using radiation, and found alpha and beta waves. He used his research and the magnetic properties of iron to find radio waves. He also discovered the atomic nucleus using others research and findings. To find this he did the Rutherford experiment. Briefly, he used a thin foil made of gold metal to find positive and negative charges in an atom. -
Niels Bohr
He figured out the structure of the atom, and their radiations. He also discovered the principle of complementary. He introduced electrons from the book he wrote on the structure of the atom. He also started the basis of the quantum theory -
Erwin Schrodinger
Erwin Schrödinger built upon the quantum mechanical model. He used a mathematical equation to describe the odds of finding the location of an electron, he called the layers, orbitals. These orbitals could be described as "electron density clouds". -
Werner Heisenberg
He established the theory of quantum mechanics and the uncertainty theory -
James Chadwick
He discovered the existence of the neutron. He found this out because when he was looking at alpha waves, bounced off, saying there was no charge in the neutron. He also used an experiment similar to this to help with the creation of the atomic bomb.
