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 GlassesLight = 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?