1. HMSA Welcome Back! Today in Class:
Midterm Corrections (up to a 90)—whatever you get done today is what I will grade!
Atoms/Nuclear Packet
Atoms & Nuclear Review/Practice Packet due FRI 1/22

2. Review: Bohr Model of the Atom
Electrons are shown in concentric shells or energy levels around the nucleus
The 1st shell can hold up to 2 electrons
The 2nd shell can hold up to 8 electrons
The 3rd shell can hold up to 18 electrons
The 4th shell can hold up to 32 electrons
When filling electrons, you fill the first (inner) shell first

3. Electrons
Valence electrons= electrons in the outermost shell of the atom

4. Lewis Structures (Electron Dot Diagrams)
A Lewis structure is in a sense a shortcut for representing the structure of an atom.
A Lewis structure contains 2 parts
1. element symbol (representing the nucleus)
2. electron dots (representing the valence electrons)

5. Lewis Structure Example
N has 5 valence electrons, so it’s Lewis structure would look like:
Maximum 2 electrons per side!
Note: by convention, you should not have more than 2 electrons per “side”
The maximum number of valence electrons you can have is 8.

6. Practice and Review
Use the example to help you fill out the Bohr Diagrams, Electron Configuration, and Valence Electrons