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?