1. Electron
Configurations

2. Valence electrons are the electrons in the
outer energy level.
1 valence electron
2 valence electrons
3 valence electrons

3. Create Lewis Dot Diagrams for the elements below.
Lewis Dot Diagrams show the number of valence electrons in an element. The diagram shows the order that dots are placed around the element’s symbol. 3 5 2 1 6 8 4 7
Create Lewis Dot Diagrams for the elements below.

4. nucleus 1st Energy Level 2nd Energy Level 3rd Energy Level
Electrons are not flying around the nucleus without any order. They organize themselves into energy levels.
When we draw atoms, we always have the nucleus in the middle. Each energy level is shown with a circle. The black dots represent the electrons in that energy level.
nucleus
1st Energy Level
2nd Energy Level
3rd Energy Level

5. Rows on the periodic table are known as periods.
All of the elements in a period have the same number of energy levels.

6. s holds up to 2 electrons p holds up to 6 electrons
Each energy level is broken down into sublevels. There are ___ sublevels that you need to be familiar with. The higher the energy level, the more sublevels it will have. 4
Sublevels:
s holds up to 2 electrons
p holds up to 6 electrons
d holds up to 10 electrons
f holds up to 14 electrons

7. Each energy level has an additional sublevel from the energy level before.
nucleus
The 1st Energy Level only has an s sublevel.
s = 2 electrons
The 2nd Energy Level has an s and p sublevel.
The 3rd Energy Level has an s, p and d sublevel.
s + p = = 8 electrons
s + p + d = = 18 electrons

8. Part of the way the periodic table is arranged is based on which sublevels are in the outer energy level of each elements atoms. p s d f

9. Scientists show the arrangement of electrons in energy levels and energy sublevels through electron configurations. We can determine the electron configuration of an element using the periodic table.

10. Phosphorous fills up the first two energy levels and lands in the p sublevel on the 3rd row. It is the 3rd element in the p sublevel on the 3rd row. We write its electron configuration like this:
1s2 2s2 2p6 3s2 3p3

11. 1s2 - represents the first energy level with its s sublevel
1s2 2s2 2p6 3s2 3p3
1s2 - represents the first energy level with its s sublevel
2s2 2p6 - represents a full second energy level showing its s and p sublevels
3s2 3p3 - represents the third energy level with its s and p sublevels. Notice that the 3p sublevel is not full for P.

12. 1s2 2s2 2p6 3s1 sodium 1s2 2s2 2p5 fluorine
What element has the electron configuration below?
1s2 2s2 2p6 3s1
sodium
What element has the electron configuration below?
1s2 2s2 2p5
fluorine

13. This essentially becomes a counting exercise once you know how to use your periodic table, but there is one important catch. The 4s sublevel is filled before the 3d sublevel. The 5s fills before the 4d, and so on. The math to explain this is complicated, but essentially it just takes less energy to make a new s sublevel than it does to make a d sublevel on the previous level.

14. 1s2 2s2 2p6 3s2 3p6 4s2 3d6 iron 1s2 2s2 2p6 3s2 3p6 4s2 3d2 titanium
What element has this electron configuration
1s2 2s2 2p6 3s2 3p6 4s2 3d6
iron
What element has this electron configuration
1s2 2s2 2p6 3s2 3p6 4s2 3d2
titanium

15. Determine which element is being represented by the electron configurations below.
magnesium
nickel
calcium
sulfur
oxygen
titanium
selenium
scandium

16. Mercury (Hg)
Hint: The highest numbered coefficient you see is always the row you should be looking in.

17. There is also a shortcut to keep from having to write out every energy level that is completely full. This is called a noble gas notation.
[Ar] 4s2 3d10 4p2 
Germanium
We use the noble gases because they are at the end of the row. This notation means that everything through the noble gas is full, plus the rest that is listed.

18. Determine which element is being represented by the electron configurations below.
manganese
silicon
nitrogen
vanadium
tin
barium
copper
iodine

19. You will also need to be able to select the noble gas that completes a configuration for a given element.
[ ? ] 5s2 4d10 4p1 
[Kr] 5s2 4d10 4p1 
Indium
The noble gas is always from the end of the previous row, so you just go up and over. This represents that everything before the row the element is on is FULL.

20. Determine which noble gas will complete the electron configurations below.Xe Ar Kr Rn Kr Ne

21. It is also important that you can select the correct electron configuration associated with an element. You should be able to find an element on the periodic table and determine what the electron configuration should be.

22. Which of the following is the electron configuration of Cobalt?
A 1s2 2s2 2p6 3s2 3p6 4s2 3d6
B 1s2 2s2 2p6 3s2 3p6 4s2 3d7
C 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d8
D 1s2 2s2 2p6 3s2 3p6 4s2  3d10 4p5

23. Determine which electron configuration matches the element in the question.b e