-
460 BCE
Democritus
Discovered that in everything there are basic matter particles called atoms.He did this by having a theory that not everything in the world is just made up or earth,water, fire, and wind. -
John Dalton
Dalton discovered that elements are only able to combine automatically when they are in fixed ratios. He observed this by doing his experiment with mixtures gases. He dropped a water bottle into were and observed that the only thing in the bottle was hydrogen and oxygen but somehow the water contained displacement leading him to come up with his atomic theory called Dalton's law of partial pressures. -
J.j Thompson
Thompson discovered electrons by using cathode ray tubes and observed to see if the cathodes deflected when using electric or magnetic fields. They did deflect when being exposed to the electric and magnetic fields which let Thompson to come up with his "plum pudding model". -
Ernest Rutherford
Discovered that negatively powered electrons orbit around positively charged particles in the center of the atom that he called the nickels. He did this by shooting alpha particles through a piece of gold foil and observed that some of the particles went through while others bounced back. This helped him to conclude his theory by observing why some alpha rays didn't shoot though the foil. -
Niels Bohr
Niels Bohr discovered that electrons don't travel in a in certain orbit but that the electrons travel in different shapes and orbits and that the orbits could tilt in the presence of a magnetic field. He relied on the quantum theory to explain his reasonings, and that's how he came up with his shell model of the atom.
