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335 BCE
Aristotle and atoms
Aristotle believed that atoms were not in everything, but the four elements, Fire, water, air, and earth. -
Antoine Lavoiser
Found out mass is conserved in a chemical reaction. -
Eugen Goldstein discovers protons
He discovered them while making experiment with cathode rays. They knocked around the electrons of atoms and attract them to a positively charged electrode -
William Crookes
Discovered thallium and further developed the atomic theory. -
W.K Roentgen produces X-Rays
W.K was the first to produce X-Rays and won a nobel prize for it. At first they were called "Röntgen rays" -
Henri Becquerel
Henri discovered radioactivity. -
J.J Thompson discovers the Atom/Electron
Wanted to test the electric discharge in a vaccum tube. -
The Curies discover polonium and radium
As a team and couple they discovered these two elements. -
Max Planck makes the "Quantum Theory"
"A theory of matter and energy based on the concept of quanta, especially quantum mechanics." -
Marie Curie
Marie found out that radioactivity doesn't depend on how atoms are arranged in molecules, but rather that it originates within the atoms themselves. -
Einstein
Einstein shows how the movement of molecules in a liquid can cause the Brownian motion. -
Hans Geiger
Hans made the first successful geiger counter, it detected alpha particles and other radiations. -
Millikan performs the oil drop experiment
His experiment helped quantify the charge of an electron. This experient contributed greatly to the atomic theory. -
Ernest Rutherford changes the atomic model
Ernest's new model showed that an atom's electrons were small and concentrated instead of being spread out. This helped him discover protons. -
Niels Bohr and the hydrogen atom
He proposed this idea based on the quantum theory. "Electrons should move around the nucleus but only in prescribed orbits. When jumping from one orbit to another with lower energy, a light quantum is emitted" -
Erwin Schrödinger
Erwin used mathematical equations to describe the likelihood of finding an electron in a certain position. -
Otto Hahn discovers Nuclear fission, first
Splits an atom with his assitant Fritz Strassman and tells Lise Meitner -
LIse Meitner discovers nuclear fission
Splitting the atom. Otto Hahn and Fritz Stassman helped discover it. -
Plutonium-239 was shown to be fissionable by used with slow neutrons and became the newest material so a nuclear bomb could be constructed.
Plutonium-239 was shown as being able to split when slow neutrons were used, this was seen as a good material for making nuclear bombs.
