1. Valence Electrons

2. What are Valence Electrons?
The valence electrons are the electrons in the last shell or energy level of an atom.
The valence electrons increase in number as you go across a period.
When you start the new period, the number drops back down to one and starts increasing again

3. Energy Level Model
Assumes electrons can orbit the nucleus ONLY at certain fixed distances from the nucleus (known as energy levels)
Electrons close to the nucleus has LESS energy than one is further
When electrons receive energy, they are in an EXCITED state. They can “jump” further away from the nucleus
When they lose/give off energy, they return back to their original energy level or GROUND STATE
When electrons return to their ground state, they give off the energy in the form of light
Electrons can jump any number of energy levels, BUT can’t get stuck in between

4. Energy Levels
There are a maximum number of electrons that can occupy each energy level.
Energy Level
Max # Electrons 1 2 8 3 18 4 32 8 10
Subdivides into sub levels

6. Electron Jumping
When electrons jump, the number of orbitals that are jumped determines the color of light which is emitted.
A longer jump has a shorter wavelength and will produced violet
A shorter jump had a longer wavelength and will produce red

8. Flame Tests
Flame tests are used to identify the presence of a relatively small number of metal ions in a compound
Different metals will emit different colors when their electrons are excited