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400 BCE
Democritus
He thought that atoms were very tiny, and were unable to be cut open. He also thought that the shape of the atom was the shape of the object that is made. For example, a water atom would be round, and then the atom for fire would have sharp edges on it. -
John Dalton
He thought that the atom was a solid sphere that you couldn't divide that you no one could destroy or remake again -
J.J. Thomson
Discovered that the atom had positively and negatively charged electrons on it, that were scattered around the outside randomly -
Max Planck
He discovered the energy that was emitted in hot water -
Ernest Rutherford
Found that there were units in the atom that could be divided. He also found that these divisible units that were positive were located in the center of the atom, and anything that was negatively charged was orbiting around the outside of the atom -
Robert Millikan
He discovered the fundamental charge of a single electron, which he discovered by doing experiments with water droplets. -
Niels Bohr
He discovered that electrons in an atom are similar to the planets in orbit, in the fact that they can only orbit in a certain circle, and cannot stray from their circle -
Erwin Schrodinger
A probability to find electrons within a space surrounding the nucleus. The cloud is denser where the probability of finding an electron is high. The cloud is less dense where the probability of finding an electron is low. -
Werner Heisnberg
When he was twenty-three, he published his uncertainty principle, and was later rewarded a Nobel prize for his subsequent researc h -
Dmitiri Mendeleev
He is the one who made the very first periodic table. This table was organized by the elements atomic number, which is according to the atoms that make up the element. -
Eugene Goldstein
With the experiments that he did, Goldstein discovered the proton on the atom. -
James Chadwick
He discovered that the atom also has a nucleus that is located in the center of the atom, with the protons. This nucleus can be positively or negatively charged, and also contributes to the atomic weight of the object
