500 BCE Leucippus500 BCE
- A Space or Void was absolutely necessary for motion to occur
+ Believed to have created the first theory of the atom.
480 BCE ZenoPrinciples/Findings:
-Stated that the universe is a single entity.
+Proposed the theory of Eleatics.
465 BCE DemocritusPrinciples/Findings:
-All matter is consisted of atoms
-Atoms cannot be destroyed
-Atoms cannot be seen.
-Atoms consist of the same parts and structuring
-Atoms are different due to their varying; shapes, masses, positions, and arrangements.
*Solids: Small, pointy Atoms
*Liquids: Large and round Atoms
*Oils: Fine, small Atoms that can slip past each other.
+His contribution to the theory was that he affirmed that the universe is composed of atoms and the void, they are in.
1640 Pierre GassendiPrinciples/Findings:
- Stated that atoms are solid and lacked in internal structures.
- Believed atoms can form into molecules.
- Atoms had not existed in earths creation.
+ Revived the idea of Atoms.
1704 Isaac NewtonPrinciples/Findings:
+Developed an idea regarding a mechanical universe which was driven by an atom.
1789 Antoine LavosierPrinciples/Findings:
- Believed atoms didn't exist. Countered and contradicted the idea of atoms
- Developed the law of conservation of mass.
+ Allowed for the chemical revolution to take place.
1803 John DaltonPrinciples/Findings:
-Everything is made of atoms. They are both indivisible and are indestructible.
-All atoms' properties are identical in any given element.
-Compounds ate made by combining multiple different types of atoms.
-When a chemical reaction occurs, the atoms are rearranged.
+Dalton is known for discovering the atomic theory.
1832 Michael FaradayPrinciples/Findings:
-Matter is recognized where lines of force met at a particular point in space.
-Did not support the atomic theory.
-Created "Faraday's laws of Electrolysis".
-Altered Dalton's theory.
-Atoms had electrical properties.
1859 J. PluckerPrinciples/Findings:
-First to experiment with electron rays in a vacuum.
+Allowed further research into the atomic theory to occur.
1873 James Clark MaxwellPrinciples/Findings:
- Stated "the void" was filled with electric and magnetic waves.
+ his work allowed for equations from Faraday to be translated.
1897 J.J. ThompsonPrinciples/Findings:
- The number of electrons equaled the number of protons while neutrons had no direct match.
- Atoms were spherical in shape.
- The protons are surrounded by electrons.
- Electrons are smaller than atoms.
+ Thomas proved that atoms were composed of protons, neutrons, and electrons. Thomas found electrons.
1898 Rutherford's Gold Foil ExperimentThe gold foil experiment was conducted to test the effect of alpha particles on matter. Rutherford placed a plate of gold foil surrounded by a sheet of sulfide. The gold was used to test whether particles to penetrate, or scatter, around 90 degrees off, they hit the sulfide screen, emitting light; or it may have deflected the beam back. This experiment ended up proving that an atom had a nucleus, and J.J. Thompson's hypothesis for the structure of an atom.
1909 Robert MillikanPrincipals/Findings:
+ Millikan was able to specify and point out the size of an electrons charge.
1911 Ernest RutherfordPrinciples/Findings:
- Atoms possess a nucleus.
- Found the proton.
- Almost all of the atoms mass is concentrated in the nucleus which is a thousand times smaller than the actual atom.
+Unified many concepts in the growing atomic theory, and disproved some as well. He also ended up classifying many different types of rays.
1922 Neils BohrPrinciples/Findings:
- Electrons travel is only possible on separately expanding orbits.
- Valence shells, can hold more electrons than inner orbits.
- The orbits determined many atoms properties.
- When an electron jumps from an outer orbit to an inner orbit, light is emitted.(calculated with the difference of 2 orbital energies.
+Bohr's explanation of the atom's orbit allowed for the explanation of the different properties of different atoms to be better understood.
1923 Werner HeisenbergPrinciples/Findings:
-Proposed and discovered that it is not possible to know a particles position and velocity at the same time.
+Heisenberg calculated the electrons' behavior and was useful to help clarify the modern view of an atom
1930 Erwin SchrodingerPrincipals/Findings:
- Proposed electrons in orbit create "standing waves".
- Only where the electron could possibly be can be described.
- Waves can be used to describe electrons through atoms.
+Proposed that the mechanics of waves are the actual mathematical method for atoms.
1932 James ChadwickPrinciple/Findings:
- Atoms have neutrons, the neutrons are found in the nucleus.
- Neutrons account for an atoms atomic mass.
+Proved that atom's nuclei were comprised of more than just protons, they were comprised of protons and neutrons. His discoveries also allowed for the advancement of the understanding of atoms' nuclei.
1935 Hans BethePrinciples/Findings:
- Found the carbon-nitrogen reaction is the same reaction that gives stars power.
+ Developed the theory of Deuteron. Allowed for a better understanding of atoms in space.
1942 Enrico FermiPrinciples/Findings:
- Proposed and established the concept of fission.
+ Aided in the creation of the first two atomic bombs that successfully forced the Japanese to surrender and end World War 2.