4. Context
We’ve learned about the parts of the atom and have spent this past week describing the mass (nucleus) of the atom
This next week is all about the outer parts of the atom—the electrons
Where they are
How we describe where they are
What that means for the atom

5. Where is the Electron?
In the quantum mechanical model, the electrons are found outside the nucleus.
To describe an electron’s location, we can includes
Its Energy Level
Its Sublevel
Its Atomic Orbital

6. Atomic Orbitals
All electrons are located in an atomic orbital or orbital.
An atomic orbital represents the area in which there is a 90% chance of finding an electron.
Each atomic orbital can hold two electrons.
Inside these orbitals, electrons take random and unpredictable paths.

7. Higher Energy Level = Bigger Sublevel
Sublevels
Based on the number of elements in our Periodic Table, there are four sublevels.
s, p, d, f
Each sublevel has a unique shape.
The size of the sublevel depends on the energy level.
Higher Energy Level = Bigger Sublevel

8. s-Sublevel sphere

10. Summary of the Sublevels
Number of Atomic Orbitals
Maximum Number of Electrons s 1 2

11. This is only one of the p-sublevel atomic orbitals.
p-Sublevel dumb bell
The picture shows one p-orbital. It is hyperlinked to an animation that shows the complete p-sublevel. You will need the following login information.
Login/Username: htaccess
Password: tiger.core
The three p orbitals are named after the axes that they represent. You can also model the p-sublevel using 6 balloons.
This is only one of the p-sublevel atomic orbitals.

12. Summary of the Sublevels
Number of Atomic Orbitals
Maximum Number of Electrons s 1 2 p 3 6

13. d-Sublevel—do NOT draw
Students are not responsible for knowing the shape of the 5 d-orbitals.
Note that the picture that is located in the center on the bottom row represents what it looks like when all of the d-orbitals are combined or put together.

14. Summary of the Sublevels
Number of Atomic Orbitals
Maximum Number of Electrons s 1 2 p 3 6 d 5 10

15. f- Sublevel: do NOT draw
Students are not responsible for knowing the shape of the 7 f-orbitals.

16. Summary of the Sublevels
Number of Atomic Orbitals
Maximum Number of Electrons s 1 2 p 3 6 d 5 10 f 7 14

18. Energy Levels Sometimes called the principal energy level
Represented by the letter, n
n = 1  First Energy Level
Each new row on the periodic table starts a new energy level.
Each energy level has a different number of sublevels, a different number of orbitals, and a different number of electrons.

19. Putting It All Together1 s 2 2
s & p 4 8 3
s, p, & d 9 18 4
s, p, d, & f 16 32

20. Reviewing Your Notes Question #1
Which sublevels will have the same shape?
3s and 3p
3p and 4p
1s and 2p
4d and 3s
4d and 4f
The letter or sublevel determines the shape.

21. Reviewing Your Notes Question #2
How many orbitals are found in a
d-sublevel? 2 4 5 10 14
Be Careful!
The d-sublevel has 5 orbitals and holds 10 electrons.
You will want to memorize that table!

22. Reviewing Your Notes Question #3
As scientists create new elements, we will need to add new sublevels to the four existing sublevels. In fact, the next sublevel will be called g. After looking at the trend in the number of orbitals for the current sublevels, how many orbitals would you predict would exist in a g-sublevel? 2 7 8 9 32
s =1
p = 3
d = 5
f = 7
g = 9

23. Electron Configurations
Electron Configurations represent the location of the electrons in an atom or ion.
1s22s22p5
the number of electrons
the energy level of the electron (n)
the sublevel

24. Reviewing Your Notes Question #4
1s22s22p63s23p4
Which element is represented by this electron configuration?
sodium
sulfur
argon
selenium
silver
Add up the exponents!
Since it is neutral, protons = electrons.

25. Reviewing Your Notes Question #5
1s22s22p63s23p4
What is the highest energy level in this electron configuration? 1 2 3 4 6
Energy level represented by the coefficient or the big number.

26. Reviewing Your Notes Question #6
1s22s22p63s23p4
How many electrons are found in the
s-sublevel? 2 4 6 8 10
= 6

27. Reviewing Your Notes Question #7
1s22s22p63s23p64s23d104p1
Which sublevel has the most electrons? s p d f
None of the above.
p = 13 electrons
d = 10 electrons
s = 8 electrons

28. Rule #1: Pauli’s Exclusion Principle
Each atomic orbital can hold two electrons.
Sublevel
# of Orbitals
Max # of Electrons s 1 2 p 3 6 d 5 10 f 7 14

29. Blocks in The Periodic Table
= s block
= d block
Row #
= p block
= f block 1 2 3 4 5 6
You can have students use their periodic table projects, which should have these blocks already color coded. 7

30. Rule #2: Aufbau Principle
Electrons will fill the atomic orbital with the lowest energy or ground state first.
1s22s22p63s23p64s23d104p5
Lowest Energy  Highest Energy

32. Blocks in The Periodic Table
= s block
= d block
Row #
= p block
= f block 1 2 3 4 5 6
You can have students use their periodic table projects, which should have these blocks already color coded. 7

33. Hund’s Rule
every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin.

35. Write the ground state electron configuration for hydrogen.1 1 s

36. Write the complete electron configuration for beryllium.2 2 1 s 2 s

37. 1 s 2 s 2 p 3 s 3 p Write the electron configuration for chlorine. 2 26 2 5 1 s 2 s 2 p 3 s 3 p

38. WYKAT—separate piece of paper
 You try these on your own! 
Fluorine
Potassium
1s22s22p5
Also, students often have trouble with the idea of skipping from Be to B since there is a large gap in the periodic table. Encourage students to follow the atomic numbers as their guide and that they should follow the atomic numbers in order just like if they were counting.
1s22s22p63s23p64s1

39. Important Reminders
Your row number tells you the energy level or coefficient for your configurations.
Know your limits for each sublevel!
You have to use your periodic table be sure that you are following the Aufbau Principle.
1s  2s  2p  3s  3p  3d
1s  2s  2p  3s  3p  4s X

40. Electron Configurations (containing the d-sublevel)
The energy level of d-sublevel will ALWAYS be one less than the row or period number.

41. Blocks in The Periodic Table
= s block
Row #
= d block
= p block
= f block 1 2
row # -1 3 4 5 6 7

42. Write the electron configuration for titanium (Ti).2 2 6 2 6 2 2 1 s 2 s 2 p 3 s 3 p 4 s 3 d

43. Write the electron configuration for iron (Fe).2 2 6 2 6 2 6 1 s 2 s 2 p 3 s 3 p 4 s 3 d

44. Write the electron configuration for bromine (Br).2 2 6 2 6 2 10 5 1 s 2 s 2 p 3 s 3 p 4 s 3 d 4 p

45. Sample Electron Configurations
 You try these on your own! 
Tellurium (Te)
Silver (Ag)
1s22s22p63s23p64s23d104p65s24d105p4
Tellurium (Te) = #52
Silver (Ag) = #47
1s22s22p63s23p64s23d104p65s24d9

46. Electron Configurations (containing the f-sublevel)
The energy level of f-sublevel will ALWAYS be two less than the row number.

47. Where does the f-block “fit in”?
The f-block is considered to be part of periods 6 and 7.

48. Blocks in The Periodic Table
= s block
= d block
Row #
= p block
= f block 1 2
row # -1 3 4 5 6 7 6 7
row # -2

49. Write the electron configuration for europium (Eu).2 2 6 2 6 2 10 6 2 10 6 2 7 1 s 2 s 2 p 3 s 3 p 4 s 3 d 4 p 5 s 4 d 5 p 6 s 4 f

50. Write the electron configuration for tungsten (W).2 2 6 2 6 2 10 6 2 10 6 2 14 4 1 s 2 s 2 p 3 s 3 p 4 s 3 d 4 p 5 s 4 d 5 p 6 s 4 f 5 d

51. Sample Electron Configurations
Bismuth (Bi)
Mercury (Hg)
1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p3
1s22s22p63s23p64s23d104p65s24d105p66s24f145d10

52. Short-Hand Notation [Ne]3s23p2
Uses a noble gas (Group 18) to represent the innermost electrons.
Outermost electrons are represented the same way.

53. Short Hand Notation Hints
To find the noble gas, look at the noble gas from the previous row or the row above the element.
The energy level or coefficient of the s and p-sublevel is equal to the row or period number.
The energy level or coefficient of
the d-sublevel is one less than the period number and for the f-sublevel two less than the period number.

54. The noble gas represents the inner most electrons
The noble gas represents the inner most electrons. For example, neon in this electron configuration represents the first 10 electrons.
Write the noble gas electron configuration for silicon. 2 2
[Ne] 3 s 3 p

55. [Ar] 4 s 3 d 2 10 Write the noble gas electron configuration for zinc.
The noble gas represents the inner most electrons. For example, neon in this electron configuration represents the first 10 electrons.
Write the noble gas electron configuration for zinc. 2 10
[Ar] 4 s 3 d

56. Sample Noble Gas Electron Configurations
 You try these on your own! 
Barium (Ba)
Antimony (Sb)
[Xe]6s2
Also, students often have trouble with the idea of skipping from Be to B since there is a large gap in the periodic table. Encourage students to follow the atomic numbers as their guide and that they should follow the atomic numbers in order just like if they were counting.
[Kr]5s24d105p3

57. Valence Electrons
Valence electrons are electrons found on the highest energy level.
1s22s22p63s23p2
What is the highest energy level?
n =3 or third energy level
How many electrons are on the highest energy level?
4 electrons
How many valence electrons are in this element?

58. Sample Questions 1s22s22p63s23p64s2 or [Ar]4s2 2 valence electrons
Write the electron configuration (the long way or short hand notation) for the following elements. For each element, determine the number of valence electrons.
Calcium
Nitrogen
Arsenic
1s22s22p63s23p64s2 or [Ar]4s2
2 valence electrons
1s22s22p3 or [Ne] 2s22p3
5 valence electrons
1s22s22p63s23p64s23d104p3 or [Ar] 4s23d104p3
5 valence electrons