-
450
Democritus
-From Ancient Greece
-questioned how many times could you cut something up that it would be in its smallest state.
-would try to cut things up into their smallest state.
-came up with the notion of atom, which is a piece of matter that is the smallest part,"atomos".
-the atom is the smallest piece of matter
-Democritus thought the atom looked like an extremely small circle -
460
Aristotle
-From Ancient Greece.
-thought differently than every other scientists.He had a different theory.
-thought that all substances were made of four elements: earth, wind, fire and water.
-he said that there was no smallest part of matter and that different substances were made up of those four elements.
-Many people followed his beliefs other than other philosophers' until they found out later on that his theory was wrong. -
John Dalton
-Known as the "father of Atomic Theory"
-Daltons Atomic theory
1.atoms make up an element
2.atoms of the same element are identical
3.atoms of different elements are different
4.atoms of different elements react to form compounds
5.atoms cannot be created or destroyed-only changed
-he thought the atom had the same make up as a pool ball because he thought that the atom was as dense as a pool ball. -
J.J. Thomson
-Used the Cathode Ray Tube experiment
-found negative particle, which is known as the electron
-He was the first scientist to discover the electron
-Also made the Plum Pudding model to show where the electrons were located and these other positively charged particles. -
Henri Becquerel
-discovered and also studied radioactivity.
-He questioned how it worked and which direction the rays went.
-he wanted to know if there was any connection between X-rays and naturally occuring phosphorescence
-his theory was accurate because we still us radiation to this day -
Marie&Pierre Curie
-they both studied radioactivity.
-they would spend their time studying X-rays or doing experiment on them.
-thought atoms were radioactive.
-discovered radium and polonium. -
Ernest Rutherford
-He was English
-Had the Gold Foil experiment
-there was heavy radiation in it.
-the particles were supposed to go straight through the gold foil to the photoelectric gate but they would reflect off the gold foil and go in different directions.
-created the Rutherford e- cloud model, which had a very small, very dense positive center which is known as the nucleus.
-So he was the first to discover the nucleus. -
Robert Millikan
-determined the charge of an electron. He did this by using the falling-drop method.
-created the oil drop experiment
-he discovered how much a charge on an atom can affect the gravity of it. -
Niels Bohr
-contributed to the understanding of the structure of the atom.
-said the atom was set up like the planets orbiting the sun.
-he thought Rutherfords model of the atom was wrong.
-he did experiments on how the atom absorbed energy and the electron would jump at certain levels of the energy. -
Quantum model
-Erwin Schrodinger created this model.
-He used the Compton effect to prove the Quantum model.
-it includes a nucleus that has neutral particles(neutrons) and positive particles(protons) -
James Chadwick
-He was English
-discoverd the neutron
-it was known as the neutron because of its lack of electric charge.
-the neutron made it possible to have heavier elements
-Chadwick inspired other scientists.
-He would use alpha particles to bomb certain elements, which produced radial. He then discovered it was a neutral particle(neutron)
-He was awarded the Nobel Prize for physics in 1935.
