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Particle Theory
Who: John Dalton
When: 1808
Where: England
What: Building on the ideas of Democritus in ancient Greece. Dalton Believed atoms were tiny particles that could never be devided. He also belived every element is made of it's own type of atom. He was the first scientist to identify atoms with weight/mass measurments.
Eperiment: He woul evaporate water and comapre it to aother gasses, later finding ou each one wieghed a differnt amount. -
Discovery of Elements
Who: J.J. Thompson
When: 1897
Where: England
What: Thompson discovered that electrons were smaller particles of an atom and were negatively charged; he dicovered cathode rays are negaatively charged.
Experiment: He dida series of experiemtns to prove that cathode rays, were actually negatively charged electrons. He set up his lab using a cathode ray gun and electromagnets, as well as other materials, as shown in the picture. -
Brownian Motion Equation
Who: Albert Enstien
When: 1905
Where: Germany
What/Experiement: Einstien discovers an equation for brownian mortion. He would add heat o liquids, observe, he would tamper with the liquids several ways to create a mathimatical model for brownain motion. -
Oil Drop Experiment
Who: Robert Millikan
When: 1909
Where: United States
What: Robert wanted to determine the size of charge on an electron. He later won a nobel prize for determining the smallest charge unit. Millikan put a charge on a tiny drop of oil, and measured how strong of an electrical field had to be to stop the oil drop from falling. He set up his experiment as show in the picture. -
Atomic Structure I
Who: Ernest Rutherford
When: 1911
Where: Manchester
Experiemtn: He used a radium gun, show radium particles at a gold leaf and observed if any radium stuck to the phosphorus sheet behind the gold. He concluded that an stom has a small heavy core. -
Atomic Structure II
Who: Niels Bohr
When: 1913
Where: England
What: Proposed that electrons traveled in fixed paths around the nucleus. Scientists still use the Bohr model to show the number of electrons in each orbit around the nucleus. He wanted to prove why nagative electrons werent being pulled into the nuceus of an atom.
Experiment: The water droplet theory. He compared a water droplet to the nucleus of an atom. He foever changed the atomic structure of an atom. Eventually disigns -
Wave Function
Who: Erwin Schrodinger
Where: Germany
When: 1926
What/Experiment: Combined several equations to stuy the behavior of electrons.He designed the atom as if it had orbitals of electrons.
