1. Chemistry– 12/13/2019 Objectives (I can…) Bell Ringer – Review
3.2 Describe the early models of the atom and construct Bohr Models of the atom.
Bell Ringer – Review
Determine the number of electrons, protons, and neutrons in potassium
Homework: Complete Bohr Model Worksheet
Read chapter 5 and complete study guide

2. Bell ringer
Determine the number of p+, e-, and n0 in the potassium #p+ = 19 #e - = 19 #n0 = 39 – 19 = 20 K

4. Constructing Bohr Models
Step 1: Determine the number of p+, e-, and n0 in the atom. Example: Lithium #p+ = 3 #e - = 3 #n0 = 4

5. Constructing Bohr Models
Step 2: Place the p+ and e- in a center nucleus
Step 3: Place electrons in orbits around the nucleus.
Place electrons in orbit around nucleus.
Fill each level with the appropriate number of electrons
Maximum electrons in each level
1st level: 2
2nd level: 8
3rd level: 18
4th level: 18
5th level: 32
#p+ = 3
#n0 = 4

6. Constructing Bohr Models
Step 2: Place the p+ and e- in a center nucleus
Step 3: Place electrons in orbits around the nucleus.
Place electrons in orbit around nucleus.
Fill each level with the appropriate number of electrons
3 p+
4 n0
2e– 1e–
#p+ = 3
#n0 = 4

7. Constructing Bohr Models
Bohr models are limited in scope, in larger atoms electrons will begin filling the next electron level before completing the earlier level. For this reason, you will not be expected to construct any Bohr models with an atomic number greater than 20. We will revisit Bohr models later

8. Constructing Bohr Models
EXAMPLE: Beryllium

9. Constructing Bohr Models
EXAMPLE: Potassium

10. Constructing Dot Diagrams
Dot diagram – A diagram to represent electrons in the outer energy level of an atom; uses the element symbol and dots

11. Constructing Dot Diagrams
Dot diagram – A diagram to represent electrons in the outer energy level of an atom; uses the element symbol and dots Example: Lithium Bohr Model Dot Diagram Li
#p+ = 3
#n0 = 4

12. Constructing Dot Diagrams
Beryllium Potassium

13. Atomic Structure
Isotopes – Atoms with the same number of protons but different number of neutrons.
Bohr Models of Isotopes
Carbon-12 Carbon-14

14. Atomic Structure
Isotopes – Atoms with the same number of protons but different number of neutrons.
Dot Diagrams
Carbon-12 Carbon-14

15. Isotope Practice Problems
Construct Bohr Models and Dot Diagrams of the following Isotopes
Lithium-6 Lithium-7
#p+ = #p+ =
#e- = #e- =
#no = #no =

16. Isotope Practice Problems
Uranium Uranium-235
#p+ = #p+ =
#e- = #e- =
#no = #no =

17. Constructing Bohr Models and Dot Diagrams
More examples or worksheet?