1. Electrons in Atoms
R. Krum

2. Bohr’s Model
Nucleus
Electron
Orbit
Energy Levels

3. Bohr’s Model Why don’t the electrons fall into the nucleus?
Move like planets around the sun.
In circular orbits at different levels.
Amounts of energy separate one level from another.

4. } Bohr’s Model Further away from the nucleus means more energy. Fifth
There is no “in between” energy Energy Levels
Fifth
Fourth
Third
Increasing energy
Second
First
Nucleus

5. The Quantum Mechanical Model
Energy is quantized. It comes in chunks.
A quanta is the amount of energy needed to move from one energy level to another.
Since the energy of an atom is never “in between” there must be a quantum leap in energy.
Schrodinger derived an equation that described the energy and position of the electrons in an atom

6. The Quantum Mechanical Model
Things that are very small behave differently from things big enough to see.
The quantum mechanical model is a mathematical solution
It is not like anything you can see.

7. The Quantum Mechanical Model
Has energy levels for electrons.
Orbits are not circular.
It can only tell us the probability of finding an electron a certain distance/space from the nucleus.

8. The Quantum Mechanical Model
The atom is found inside a blurry “electron cloud”
An area where there is a greater chance of finding an electron.
Draw a line or picture at 90 % probability positions

9. Block Table This shows the different blocks in the Periodic Table.
It also shows in what order to write electron configurations (1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d,7p)

10. Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p 3s
Notice how the 4d energy > 5s energy;
4f energy > 5p energy

11. Electron Configurations
The way electrons are arranged in atoms.
Aufbau principle- electrons enter the lowest energy first. [“electrons are lazy”]
This causes difficulties because of the overlap of orbitals of different energies.
Pauli Exclusion Principle- at most 2 electrons per orbital – having different “spins”

12. S orbitals There’s an s orbital for every energy level
Spherical shaped
Each s orbital can hold 2 electrons
Called the 1s, 2s, 3s, etc.. orbitals.

13. Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p H 1s1

14. Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p He 1s2

15. Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p
Li 1s22s1

16. Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p
Be 1s12s2

17. P orbitals Start at the second energy level
3 different directions: X, Y, Z
Each can hold 2 electrons
Each is described as “dumbell” shaped

18. P Orbitals

19. Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p
B 1s22s22p1

20. Electron Configuration
Hund’s Rule- When electrons occupy orbitals of equal energy they don’t pair up until they have to.
[ “don’t want roomate unless it costs more” – more energy in this case]
Chicken rule!!!!!!

21. Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p
C 1s22s22p2

22. Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p
N 1s22s22p3

23. Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p
O 1s22s22p4

24. Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p
F 1s22s22p5

25. Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p
Ne 1s22s22p6

26. Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p
Na 1s22s22p63s1

27. Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p
Mg 1s22s22p63s2

28. Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p 3s 2p
Al 1s22s22p63s23p1

29. Electron Configuration
Hund’s Rule- When electrons occupy orbitals of equal energy they don’t pair up until they have to.
[ “don’t want roomate unless it costs more” – more energy in this case]

30. Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p 3s 2p
Si 1s22s22p63s23p2

31. Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p 3s 2p
P 1s22s22p63s23p3

32. Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p 3s 2p
S 1s22s22p63s23p4

33. Other ways to show this __ __ __ __ __ __ __ __ __ __ __ __ __ __ __
1s s p s p s d
__ __ __ __ __ __ __ __ __ __ __ __ __ __ __
1s s p s p s d

34. Energy diagrams for Phosphorous atom
Other ways to show this
1s s p s p s d
__ __ __ __ __ __ __ __ __ __ __ __ __ __ __
1s s p s p s d
Energy diagrams for Phosphorous atom

35. D orbitals Start at the third energy level 5 different shapes
Each can hold 2 electrons

36. F orbitals Start at the fourth energy level
Have seven different shapes
2 electrons per shape

37. F orbitals

38. Block Table This shows the different blocks in the Periodic Table.
It also shows in what order to write electron configurations (1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d,7p)

39. The easy way to remember – draw this chart in this way
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f
6s 6p 6d 6f
7s 7p 7d 7f
1s2
2 electrons

40. Fill from the bottom up following the arrows
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f
6s 6p 6d 6f
7s 7p 7d 7f
1s2 2s2
4 electrons total

41. Fill from the bottom up following the arrows
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f
6s 6p 6d 6f
7s 7p 7d 7f
1s2 2s2 2p6 3s2
12 electrons total

42. Fill from the bottom up following the arrows
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f
6s 6p 6d 6f
7s 7p 7d 7f
1s2 2s2 2p6 3s2 3p6 4s2
20 electrons total

43. Fill from the bottom up following the arrows
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f
6s 6p 6d 6f
7s 7p 7d 7f
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2
38 electrons total

44. Fill from the bottom up following the arrows
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f
6s 6p 6d 6f
7s 7p 7d 7f
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2
56 electrons total

45. Fill from the bottom up following the arrows
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f
6s 6p 6d 6f
7s 7p 7d 7f
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2
88 electrons total

46. Fill from the bottom up following the arrows
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f
6s 6p 6d 6f
7s 7p 7d 7f
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 6d10 7p6
108 electrons

47. Write these electron configurations
Titanium - 22 electrons
Vanadium - 23 electrons

48. Write these electron configurations
Titanium - 22 electrons
1s22s22p63s23p64s23d2
Vanadium - 23 electrons
1s22s22p63s23p64s23d3

49. Short hand method Use closest previous Noble Gas as “starting point”
Add configuration on from there…
Try Phosphorous
Long way: 1s22s22p63s23p3
Noble gas way:
1s22s22p6
[Ne] 3s23p3

50. Summary # of shapes Max electrons Starts at energy level s 1 2 1 p 3 6d 5 10 3 7 14 4 f

51. By Energy Level First Energy Level only s orbital only 2 electrons 1s2
Second Energy Level
s and p orbitals are available
2 in s, 6 in p
2s22p6
8 total electrons

52. By Energy Level Third energy level s, p, and d orbitals
2 in s, 6 in p, and 10 in d
3s23p63d10
18 total electrons
Fourth energy level
s,p,d, and f orbitals
2 in s, 6 in p, 10 in d, and 14 in f
4s24p64d104f14
32 total electrons

53. Electron Dot Diagrams (aka Lewis Dot Structures)
How do we draw a picture for the number of electrons an atom has?
If you want to see how atoms of one element will react, it is handy to have an easier way to represent the atoms and the electrons in their outer energy levels.
You can do this with electron dot diagrams.
An electric dot diagram is the symbol for the element surrounded by as many dots as there are electrons in its outer energy level.

54. LEWIS (DOT) SYMBOLS FOR THE ELEMENTS
A) A Lewis dot structure for an atom consists of the symbol for the element and one dot for each valence electron. It is used for the s and p block elements, the representative elements.

55. How to Write E.D.D.’s
The dots are written in pairs on four sides of the element symbol.
Start by writing one dot on the top of the element symbol, then work your way around adding dots to the right, bottom, and left.