1. Arrangement of Electrons
Properties of light: acts as both a wave and a particle
AS A WAVE
defn: electromagnetic radiation: a form of energy that exhibits wavelike behavior as it travels through space.
ex: x-ray, infrared light, microwaves, and radio waves.
All the forms of electromagnetic radiation form the electromagnetic spectrum.

2. defn: wavelength: the distance between corresponding points on adjacent waves.
defn: frequency: the number of waves that pass a given point in a specific time(usually one second)

3. defn: Photoelectric effect: refers to the emission of electrons from a metal when light shines on the metal.

4. Light as a particle
defn: quantum: a quantum of energy is the minimum quantity of energy that can be lost or gained by an atom.
defn: photon: a particle of electromagnetic radiation having zero mass and carrying a quantum of energy.
The lowest energy state of an atom is its ground state.
An atoms excited state is when it has more energy than in its ground state.
When an excited atom returns to its ground state it gives off energy in the form of electromagnetic radiation.
Line emission spectra is produced when an electron moves to a lower energy level.

5. The Bohr model of the atom was an attempt to explain hydrogen’s line emission spectrum. Bohr’s model worked for hydrogen but failed to explain the spectra when more than one electron was present.