1. The Bohr Model

2. Recall the structure of the atom

3. Recall the structure of the atom
Electron
Shells
Neutron
Nucleus
Proton
Valence shell

4. Recall the structure of the atom
Electron
Shells
Neutron
Nucleus
Proton
Valence shell
Sometimes, we need to represent atoms in a simplified way

5. Bohr Diagrams

6. Bohr Diagrams
Bohr diagrams are a simplified way to represent atoms

7. Bohr Diagrams Bohr diagrams are a simplified way to represent atoms
The key features of a Bohr diagram are:

8. Bohr Diagrams Bohr diagrams are a simplified way to represent atoms
The key features of a Bohr diagram are:
Electron shells

9. Bohr Diagrams Bohr diagrams are a simplified way to represent atoms
The key features of a Bohr diagram are:
Electron shells
Electron placement within the shells

10. Bohr Diagrams Bohr diagrams are a simplified way to represent atoms
The key features of a Bohr diagram are:
Electron shells
Electron placement within the shells
A simplified nucleus to show what element it is (this can be done in different ways)

11. Bohr Diagrams Bohr diagrams are a simplified way to represent atoms
The key features of a Bohr diagram are:
Electron shells
Electron placement within the shells
A simplified nucleus to show what element it is (this can be done in different ways)

12. Bohr Diagrams Bohr diagrams are a simplified way to represent atoms
The key features of a Bohr diagram are:
Electron shells
Electron placement within the shells
A simplified nucleus to show what element it is (this can be done in different ways)

13. Bohr Diagrams Bohr diagrams are a simplified way to represent atoms
The key features of a Bohr diagram are:
Electron shells
Electron placement within the shells
A simplified nucleus to show what element it is (this can be done in different ways)
The primary purpose of a Bohr diagram is to show electron placement

14. Electrons
Electrons are not randomly dispersed amongst the electron shells

15. Electrons
Electrons are not randomly dispersed amongst the electron shells
Each electron shell can only hold a specific number of electrons

16. Electrons
Electrons are not randomly dispersed amongst the electron shells
Each electron shell can only hold a specific number of electrons
First shell: up to two electrons

17. Electrons
Electrons are not randomly dispersed amongst the electron shells
Each electron shell can only hold a specific number of electrons
First shell: up to two electrons
Second shell: up to eight electrons

18. Electrons
Electrons are not randomly dispersed amongst the electron shells
Each electron shell can only hold a specific number of electrons
First shell: up to two electrons
Second shell: up to eight electrons
Third shell: up to eight electrons

19. Electrons
Electrons are not randomly dispersed amongst the electron shells
Each electron shell can only hold a specific number of electrons
First shell: up to two electrons
Second shell: up to eight electrons
Third shell: up to eight electrons
Fourth shell: up to eighteen electrons

20. Electrons
Electrons are not randomly dispersed amongst the electron shells
Each electron shell can only hold a specific number of electrons
First shell: up to two electrons
Second shell: up to eight electrons
Third shell: up to eight electrons
Fourth shell: up to eighteen electrons
Etc. (there are more shells but we will deal with just the first four)

21. Electrons
Electrons are not randomly dispersed amongst the electron shells
Each electron shell can only hold a specific number of electrons
First shell: up to two electrons
Second shell: up to eight electrons
Third shell: up to eight electrons
Fourth shell: up to eighteen electrons
Etc. (there are more shells but we will deal with just the first four)
The electron shells fill in a specific order

22. Electrons
Electrons are not randomly dispersed amongst the electron shells
Each electron shell can only hold a specific number of electrons
First shell: up to two electrons
Second shell: up to eight electrons
Third shell: up to eight electrons
Fourth shell: up to eighteen electrons
Etc. (there are more shells but we will deal with just the first four)
The electron shells fill in a specific order
The first shell must be filled before any electrons can enter the second shell

23. Electrons
Electrons are not randomly dispersed amongst the electron shells
Each electron shell can only hold a specific number of electrons
First shell: up to two electrons
Second shell: up to eight electrons
Third shell: up to eight electrons
Fourth shell: up to eighteen electrons
Etc. (there are more shells but we will deal with just the first four)
The electron shells fill in a specific order
The first shell must be filled before any electrons can enter the second shell
The second shell must be filled before any electrons can enter the third shell

24. Electrons
Electrons are not randomly dispersed amongst the electron shells
Each electron shell can only hold a specific number of electrons
First shell: up to two electrons
Second shell: up to eight electrons
Third shell: up to eight electrons
Fourth shell: up to eighteen electrons
Etc. (there are more shells but we will deal with just the first four)
The electron shells fill in a specific order
The first shell must be filled before any electrons can enter the second shell
The second shell must be filled before any electrons can enter the third shell
Etc.

25. Electrons
Electrons are not randomly dispersed amongst the electron shells
Each electron shell can only hold a specific number of electrons
First shell: up to two electrons
Second shell: up to eight electrons
Third shell: up to eight electrons
Fourth shell: up to eighteen electrons
Etc. (there are more shells but we will deal with just the first four)
The electron shells fill in a specific order
The first shell must be filled before any electrons can enter the second shell
The second shell must be filled before any electrons can enter the third shell
Etc.
The only electron shell that can be partially filled is the valence shell

26. Example: Carbon

27. Example: Carbon
Carbon has:
6 protons
6 electrons

28. Example: Carbon Carbon has:
6 protons
6 electrons
Recall: in order to be neutral, an atom must have the same number of protons as electrons
−1 =0
Assume atoms are neutral unless specified otherwise (more to come next lesson)

29. Example: Carbon
Carbon has:
6 protons
6 electrons
Draw nucleus

30. Example: Carbon Carbon has: Draw nucleus 6 protons
6 electrons
Draw nucleus
Label number of protons
6 𝑝 +

31. Example: Carbon Carbon has: Draw nucleus Draw first electron shell
6 protons
6 electrons
Draw nucleus
Label number of protons
Draw first electron shell
6 𝑝 +

32. Example: Carbon Carbon has: Draw nucleus Draw first electron shell
6 protons
6 electrons
Draw nucleus
Label number of protons
Draw first electron shell
Fill first electron shell
Can contain up to two electrons
6 𝑝 +

33. Example: Carbon Carbon has: Draw nucleus Draw first electron shell
6 protons
6 electrons
Draw nucleus
Label number of protons
Draw first electron shell
Fill first electron shell
Can contain up to two electrons
6 – 2 = 4 electrons, we still need to draw four more electrons
6 𝑝 +

34. Example: Carbon Carbon has: Draw nucleus Draw first electron shell
6 protons
6 electrons
Draw nucleus
Label number of protons
Draw first electron shell
Fill first electron shell
Can contain up to two electrons
6 – 2 = 4 electrons, we still need to draw four more electrons
Draw second shell
6 𝑝 +

35. Example: Carbon Carbon has: Draw nucleus Draw first electron shell
6 protons
6 electrons
Draw nucleus
Label number of protons
Draw first electron shell
Fill first electron shell
Can contain up to two electrons
6 – 2 = 4 electrons, we still need to draw four more electrons
Draw second shell
Place final four electrons in shell
6 𝑝 +

36. Example: Magnesium

37. Example: Magnesium
Magnesium has:
12 protons
12 electrons

38. Example: Magnesium
Magnesium has:
12 protons
12 electrons
Draw nucleus

39. Example: Magnesium Magnesium has: Draw nucleus 12 protons
12 electrons
Draw nucleus
Label number of protons
12 𝑝 +

40. Example: Magnesium Magnesium has: Draw nucleus
12 protons
12 electrons
Draw nucleus
Label number of protons
Draw first electron shell
12 𝑝 +

41. Example: Magnesium Magnesium has: Draw nucleus
12 protons
12 electrons
Draw nucleus
Label number of protons
Draw first electron shell
Fill first electron shell
Can contain up to two electrons
12 𝑝 +

42. Example: Magnesium Magnesium has: Draw nucleus
12 protons
12 electrons
Draw nucleus
Label number of protons
Draw first electron shell
Fill first electron shell
Can contain up to two electrons
12 – 2 = 10 electrons, we still need to draw ten more electrons
12 𝑝 +

43. Example: Magnesium Magnesium has: Draw nucleus
12 protons
12 electrons
Draw nucleus
Label number of protons
Draw first electron shell
Fill first electron shell
Can contain up to two electrons
12 – 2 = 10 electrons, we still need to draw ten more electrons
Draw second shell
12 𝑝 +

44. Example: Magnesium Magnesium has: Draw nucleus
12 protons
12 electrons
Draw nucleus
Label number of protons
Draw first electron shell
Fill first electron shell
Can contain up to two electrons
12 – 2 = 10 electrons, we still need to draw ten more electrons
Draw second shell
Fill second electron shell
Can contain up to eight electrons
12 𝑝 +

45. Example: Magnesium Magnesium has: Draw nucleus
12 protons
12 electrons
Draw nucleus
Label number of protons
Draw first electron shell
Fill first electron shell
Can contain up to two electrons
12 – 2 = 10 electrons, we still need to draw ten more electrons
Draw second shell
Fill second electron shell
Can contain up to eight electrons
10 – 8 = 2 electrons, we still need to draw two more electrons
12 𝑝 +

46. Example: Magnesium Magnesium has: Draw nucleus
12 protons
12 electrons
Draw nucleus
Label number of protons
Draw first electron shell
Fill first electron shell
Can contain up to two electrons
12 – 2 = 10 electrons, we still need to draw ten more electrons
Draw second shell
Fill second electron shell
Can contain up to eight electrons
10 – 8 = 2 electrons, we still need to draw two more electrons
Draw third shell
12 𝑝 +

47. Example: Magnesium Magnesium has: Draw nucleus 12 protons
12 electrons
Draw nucleus
Label number of protons
Draw first electron shell
Fill first electron shell
Can contain up to two electrons
12 – 2 = 10 electrons, we still need to draw ten more electrons
Draw second shell
Fill second electron shell
Can contain up to eight electrons
10 – 8 = 2 electrons, we still need to draw two more electrons
Draw third shell
Place remaining two electrons in shell
12 𝑝 +

48. Practice Time!!!

49. Draw the following Bohr diagrams

50. Draw the following Bohr diagrams
Hydrogen
Phosphorous

51. Draw the following Bohr diagrams
Hydrogen
Phosphorous
1 𝑝 +

52. Draw the following Bohr diagrams
Hydrogen
Phosphorous
1 𝑝 +
15 𝑝 +

53. What element is represented by the Bohr diagram?

54. What element is represented by the Bohr diagram?

55. What element is represented by the Bohr diagram?
Answer: Neon

56. What element is represented by the Bohr diagram?
Answer: Neon

57. What element is represented by the Bohr diagram?
Answer: Sodium
Answer: Neon

58. What element is represented in the following Bohr diagrams

59. What element is represented in the following Bohr diagrams

60. What element is represented in the following Bohr diagrams
Answer: oxygen
There are 8 electrons
Must have 8 protons
Must be oxygen

61. What element is represented in the following Bohr diagrams
Answer: oxygen
There are 8 electrons
Must have 8 protons
Must be oxygen ?

62. What element is represented in the following Bohr diagrams
Answer: oxygen
There are 8 electrons
Must have 8 protons
Must be oxygen
Answer: argon
There are 18 electrons
Must have 18 protons
Must be argon ?

63. How many shells would the following elements have?

64. How many shells would the following elements have?
Lithium

65. How many shells would the following elements have?
Lithium
Answer: 2
Lithium has 3 protons
Must have 3 electrons
First shell: 2
Second shell: 1

66. How many shells would the following elements have?
Lithium
Answer: 2
Lithium has 3 protons
Must have 3 electrons
First shell: 2
Second shell: 1
Calcium

67. How many shells would the following elements have?
Lithium
Answer: 2
Lithium has 3 protons
Must have 3 electrons
First shell: 2
Second shell: 1
Calcium
Answer: 4
calcium has 20 protons
Must have 20 electrons
First shell: 2
Second shell: 8
Third shell: 8
Fourth shell: 2