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Atomic theory = Dalton
Electron discovery = JJ Thomson
Electron charge = Millikan
Nucleus discovery = Rutherford
Neutron = Chadwick
Neils Bohr
What keeps the negative electrons from falling toward the positive nucleus?
Light as a stream of photons
Tiny little packets of quantum energy
Light as a Wave
Light: travels in waves, made up of photons
Photons : zero mass, contain a quantum energy
Glasses Light = electromagnetic radiation
energy from light affects electrons
• Ground State: lowest energy of atom.
• Excited State: atom absorbed energy higher than ground state.
• Electromagnetic radiation: energy given off when excited atom returns
to its ground state.
“production of colored light / luster of a metal”
An excited atom returns to a lower energy level.
Ground State
Excited State
Photon emitted
The color of the photon emitted depends on the energy change that produces it.
Excited state one
Excited state two
Each photon emitted corresponds to a particular energy change.
4 excited states… each one may emit a different color
Excited neon atoms emit light when falling back to the ground state or to a lower-energy excited state.
Show video: fireworks
Fireworks lab:
? According to the Bohr’s Model for Hydrogen atom what is
principal number the electron that produces the 1875 infrared wavelength?
? According to the Bohr’s Model…..produces a blue light when the electron fall back from energy level 4 to energy level_________.
? For hydrogen to produce a UV wavelength the electron must fall back from what to what?