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465
Aristotle
Aristotle was another greek philosopher. He was very well-known and respected. He believed that everything was made up of four basic elements, fire, water, earth and wind. He was incorrect. -
465
Democritis
Democritis was a philosopher in 465, he was largely discriminated against compared to Aristotle. His theroy was based on "atmos" particles. He believed that they could not be broken down any more. He was very correct. -
500
"Atmos" Particles
Atmos particles are so small they cannot be broken down. This was the earliest dicscovery of what we now call atoms. -
500
Four Element Theory
Aristotle had a theory that everything in the universe was made of four elements. Fire, Water, Earth and Wind. He was of course wrong. -
Billiard Ball Model
this theory said that elements are made of extremely small particles called atoms.
Alao that atoms of an element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties, and that atoms cannot be divided, created, or destroyed. -
John Dalton
John Dalton was an English chemist. His atomic model was called the "Billiard Ball Model". -
Sir William Crookes
Sir William Crookes was a British chemist and physicist who invented the Crookes tube. It was a glass tube, closed off at both ends, with a vacuum pump connected. Two electrodes were sealed into the glass of the tube, and connected to a battery. Voltage was increase until a flow was detected. -
Crookes' Tube
It was a glass tube, closed off at both ends, with a vacuum pump connected. Two electrodes were sealed into the glass of the tube, and connected to a battery. Voltage was increase until a flow was detected. -
J.J. Thompson
J.J. Thompson took the crookes tube, and experiented. He held a magnet to the side of the tube, and tried to direct the beam of light. The results were astounding. When a negatively charged magnet was placed of one side, the beam was deflected from it. Thompson decided that the beam must have a negative charge if it was attracted to the positive side. The negative charges became known as electrons. Thompson called this the "Plum Pudding Model" there were positive and negative particles together. -
Plum Pudding Model
J.J. Thompson held a magnet to the side of the tube, and tried to direct the beam of light. The results were astounding. When a negatively charged magnet was placed of one side, the beam was deflected from it. Thompson decided that the beam must have a negative charge if it was attracted to the positive side. The negative charges became known as electrons. Thompson called this the "Plum Pudding Model" there were positive and negative particles together. -
Ernest Rutherford
Ernest Rutherford was one of Mr. Thompson'd students. He invented a detector for electromagnetic waves. He also reported the existence of alpha and beta rays in uranium radiation and some of their properties. -
Gold Foil Experiment
This was a landmark experiment. Scientists discovered that every atom had a nucleus where its positive charge is centered. It was done under the supervision of Ernest Rutherford. -
Neils Bohr
Neils Bohr was a scientist in 1913. He invented the Electron Cloud Model. Although Neils originally thought of this, his model was build on later by many scientists. -
Orbitals
This is a mathmatical function that decribes the wave-like behavior of electrons in an atom.
