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30 Cards in this Set

  • Front
  • Back
Conducted scattering experiments by firing subatomic particles at atoms in order to ascertain that the atom is composed of a dense nucleus with tiny orbitting electrons.
John Dalton
Used the law of definite proportions to argue for the existance of atoms.
J.J. Thompson
Discovered the electron. Argued that electrons must be contained inside atoms.
Kinetic Theory
The description of the macroscopic properties of atoms.
A measure of energy per atom.
Mean free path
The average distance that a molecule travels between collisions.
Brownian motion
tiny particles suspended in any fuild exhibit erratic motion.
Milikan's oil drop experiment
Suspended oil droplets in electric field in order to determine the value of the charge on an individual electron. Could hold a particle constant when the upward electrical force was equal to the force of gravity.
quanta of light
Max Planck
First person to propose that electromagnetic radiation must be quantized. h is planck's constant.
Lorentz force
The force on each electron in fields E and B
Photoelectric effect
Discovered by Hertz, a metal exposed to light is found to eject electrons from its surface.
Stopping Potential
V when all current ceases. Not enough enough V to overcome retarding potential
Work function
for any metal, the definite minimum energy to remove and elction.
Arthur Compton
His observations of the scattering of electromagnetic radiation by atoms showed clearly that photons should be regarded as particles.
W. L. Bragg
Used crystals as X-ray diffraction gratings. Theta=theta (prime).
Bragg Law
Characteristic X-rays
the x-ray spikes which occur at certain frequencies.
Compton effect
The American physicist Arthur Holly Compton explained the wavelength increase when high frequency X-rays were scattered off electrons by considering X-rays as composed of discrete pulses, or quanta, of electromagnetic energy
Niels Bohr
Devised a model of the hydrogen atom, that , while not complete, was a major stepping stone to quantum mechanics.
Showed that the wavelengths of X-rays emitted by atoms depend on the atomic number exactly as predicted by the Bohr model.
Elastic collision
total KE conserved
Franck-Hertz Experiment
Was a physics experiment that provided support for the Bohr model of the atom.Stream of electrons passed through a tube of mercury vapor.There is a grid in front on an anode. The elctrons that pass through the grid and have enough energy to overcome the retarding force will reach anode. Shows quantized energy levels.
De Broglie's Hypothesis
Proposed material particles should also show a wave particle duality.
Wave function
The mathematical function that specifies the wave disturbance at each point of space and time.
Sinusoidal Waves
A wave with definite frequency and wavelength. Stretches infinitely.
Maximum displacement of the string from its mean position.
Wave Packet
Type of wave function localized in some region.
Fourier analysis
the study of the composition of functions as sums of sinusoidal waves.
Heisenberg Uncertainty relationship
Can't know the position and momentum of a particle. Choose one.