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Democritus
Democritus was the philosopher who gave the atom it's name. He came across the invention of the atom when he questioned, "If I keep breaking a piece of matter in half, when will it not break anymore?" He decided that the smallest piece of matter would be known as an atom. -
John Dalton
John Dalton preformed experiments which supported the theory that there are particles in each piece of matter. However, he did not create any theories about their structure. He did, however, know that it was a fundamental molecule. -
J.J. Thompson
Thompson is remembered for his model, commonly known as "the lump of pudding model". Thompson discovered electrons and knew that they were negatively charged. In addition, he knew that the matter the electrons surrounded were positively charged. This model was the model utilized until Ernest Rutherford. -
Max Planck
He created the initial study, supporting the theory that if "you vibrate atoms strong enough, such as when you heat an object until it glows, you can measure the energy only in discrete units". They were known as quanta. His discovery is the first step into the discovery of photons. -
Ernest Rutherford
Rutherford tested the radioactivity of the atom to conclude that it is nuclear. Later, in 1917, he bacame the first scientist the split the atom elements, changing nitrogen into oxygen. It was his contribution that lead us to the familiarity of the radioactivity of atoms and the discovery of protons. However, the flaws in his atomic theory was that if the electrons would lose energy, then the atom would defeat itself. Neils Bohr's model corrected this flaw. -
Neils Bohr
Neils Bohr expanded on the ideas of Ernest Rutherford with the help of quantum physics. Neils Bohr created a model where electrons move in specific clouds without emitting radiation (because they lose energy while accelerating around the nucleus). He proved this using Einstein's theory of "photons". A photon is a particle that has forms of radiation. According to Bohr, an electron moves by absorbing a photon. More electrons will circle another cloud with a larger diameter to emit more photons. -
Arnold Sommerfeld
Bohr collaberated with the sceintist, Arnold Sommerfeld to expand on his model of the atom. The Bohr-Summerfeld model added the theory that the orbits in which electrons travel have different shapes. In addition, they thought that the angles at which the orbits sit have different magnetic fields. -
Wolfgang Pauli
Pauli theorized that the electron spins while it is orbitting the nucleus. This kind of resembles the way the Earth spins while it is orbitting the sun. However, the electron can spin in both directions. The rule is that "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". -
Werner Heisenberg
Around the same time of Schodingers theory, Werner Heisenberg had a theory based on mathamatics, known as the matirx mechanics. The matrix mechanics explains how atoms behaved. Though it differened from Schodingers theories, both were equally accurate in mathamatics. It was then that he explained the "Heisenberg uncertainty principle" which outlines the uncertainty that comes with measuring two forces simultaneously. -
Erwin Schrodinger
Shrodinger was the scientist who created the model of the atom using the theory that atoms consisted of particle waves. There was no name for his wave mechanics so he gave it a greek symbol which we can refer to. -
James Chadwick
James Chadwick was the physicist that discovered the neutron of the atom. He declared tha the neutron in itself carried no charge. When he saw the variation of masses of the same atom he concluded that an atom can have different numbers of neutrons. These were known as isotopes. He also identified that a proton and neutron together would be known as a nucleon -
Paul Dirac (Carl Anderson)
What physicist call positron's are the theory that was first thought up by Paul Dirac. Dirac was skeptical of the theory that an electron can have a positive charge. It wan't untl Carl Andersons discovery of the "anti-electron" that DIrac's equations were proven. For every matter there is an anti-matter or opposite. This was the first discovery of anti electrons. Later there were anti protons and neutrons.
