1. Representing Atoms Visually Bohr Models

2. Atomic Structure Review Protons = positive charge; atomic number Neutrons = neutral; atomic mass (rounded) – atomic number protons and neutrons are located in the nucleus Electrons = negative charge; same as # protons in a neutral atom Electrons are located in shells, energy levels or orbitals surrounding the nucleus. Each shell/level/orbital holds a specific number of electrons

3. What are Bohr models? One type of visual representation of an atom There are three things that you need to have: Number of shells (period #) Number of valence electrons (group #) Total number of electrons

4. How do I draw a Bohr model? 1. Determine the number of electrons, protons, & neutrons from the atomic number and atomic mass. 2. Draw a little circle for the nucleus and label inside with the number of protons and neutrons 1. p + = protons, n 0 = neutrons 3. Determine the number of energy levels from the period that the element is in. Draw larger circles around the nucleus for each energy level. 4. Place dots representing the electrons in each energy level on these circles, according to how many each level can hold.

5. Using the PT for Bohr models Each period represents an energy level Each squarer (element) represents an electron NOTE: Each period has a certain number of squares (electrons). This will tell you how many electrons each level can hold. Energy LevelElectrons Allowed 12 28 38

6. 1 2 13 14 15 16 17 18 1 2 3 4 5 6 7 6 7 Transition Metals Period 1 = 1 Electron Shell Period 2 = 2 Electron Shells Period 3 = 3 Electron Shells Period 4 = 4 Electron Shells Period 5 = 5 Electron Shells Period 6 = 6 Electron Shells Period 7 = 7 Electron Shell Period 6 = 6 Electron Shells Period 7 = 7 Electron Shells

7. 1 Valence Electron2 Valence Electron3 Valence Electron4 Valence Electron5 Valence Electron6 Valence Electron7 Valence Electron8 Valence Electron

8. Example of a Bohr model Chlorine

9. Bohr Practice 1 per 2 per 3 per 2 8 8 Argon (Ar) Oxygen (O) Neon (Ne) Silicon (Si) Phosphorus (P)

10. Which element is this? Helium

11. Argon Beryllium Barium Boron

12. MAG-NE-SIUM

13. Classwork/Homework Complete your worksheet on Bohr models (both sides) Due T 10/25/11