1. Electron Configurations

2. Opening Questions: Life on the Edge
The atoms below have similar reactivity and chemical behavior.
1. Where are these elements located on the periodic table?
2. What do you think might be responsible for their similar properties?

3. 1 2 13 14 15 16 17 18 1e- 2e- Hydrogen Lithium Sodium 8e- 7e- 4e- 6e-
Potassium
3e-
18e-
Calcium
Gallium
Germanium
Selenium
Krypton
Bromine
Magnesium
Beryllium
Aluminum
Boron
Carbon
Nitrogen
Oxygen
Fluorine
5e-
Silicon
Sulfur
Phosphorus
Argon
Helium
Neon 1 2 13 14 15 16 17 18

4. Summary: Life on the Edge
Core electrons: electrons that are located in all of the inner shells
Valence electrons: electrons that are in the outermost shell ONLY
Elements with the same # of valence electrons have similar chemical and physical properties.
Same group (column)

5. Summary: Life on the Edge
As you move across a row, you add electrons.
As you move down a group, you add electron shells.
1e-
2e-
Hydrogen
Lithium
Sodium
8e-
7e-
4e-
6e-
Potassium
3e-
18e-
Calcium
Gallium
Germanium
Selenium
Krypton
Bromine
Magnesium
Beryllium
Aluminum
Boron
Carbon
Nitrogen
Oxygen
Fluorine
5e-
Silicon
Sulfur
Phosphorus
Argon
Helium
Neon 1 2 13 14 15 16 17 18

6. Check-in: Life on the Edge
Provide the following information for element number 34.
The element’s name and symbol
The number of protons in the nucleus
The total number of electrons for this element
The number of valence electrons
The group number for this element
The names of other elements with similar properties

7. Opening Questions: Shell Game
The two drawings show two ways of representing the electron arrangement of calcium (Ca).
1. Name at least two similarities.
2. Name at least two differences.

8. Electron Shells and Subshells
Electrons are first arranged into shells/energy levels
labeled n = 1 for the 1st shell, n = 2 for the 2nd shell, etc.
Each shell is further divided into subshells
designated s, p, d, and f

9. Electron Shells and Subshells
Where do subshells start?
s: 1st shell/energy level
p: 2nd shell/energy level
d: 3rd shell/energy level
f: 4th shell/energy level 4

10. Electron Shells and Subshells
Each subshell has a distinct shape

11. Electron Configuration Notation
Electron configuration: a list of all the subshells that contain electrons for a given element
electrons occupy lowest energy levels available
Notation: 1
number of electrons in subshell 1 s
subshell
value of energy level

12. Electron Configurations
Which element has the configuration 1s22s22p5?

13. Electron Configurations
Write the electron configuration for this element.
How many e- in each subshell?
s: 2 electrons
p: 6 electrons
d: 10 electrons
f: 14 electrons

14. Check-in: Shell Game
Identify the element with the following electron configuration.
1s22s22p63s22p64s23d104p3
What is the outermost subshell for bromine, Br?
Name an element with electrons in the f-block.
What is the electron configuration for the element with the atomic number 13?
How many valence electrons does krypton, Kr, have? How do you know?

15. Shorthand Electron Configurations
Instead of writing out all the filled subshells, you can use a shorthand (or noble gas) configuration.
Use the last noble gas as your starting point.
EXAMPLE:
Bromine’s full electron configuration: 1s22s22p63s23p64s23d104p5
Bromine’s shorthand configuration: [Ar]4s23d104p5

16. Shorthand Electron Configurations
Write the shorthand electron configuration for this element
Period 1 2 3 4 5 6 7 1s 2s 3s 4s 5s 6s 7s 3d 4d 5d 6d 2p 3p 4p 5p 6p 4f 5f
Periodic Table: Subshells
2 elements
10 elements
6 elements
14 elements

17. PRACTICE! Go Figure Worksheet…
Start on the backside:
- question #3 b) and d)

18. D-block Elements
Period 1 2 3 4 5 6 7 1s 2s 3s 4s 5s 6s 7s 3d 4d 5d 6d 2p 3p 4p 5p 6p 4f 5f
Periodic Table: Subshells
2 elements
10 elements
6 elements
14 elements
The d-block elements do not follow the nice pattern seen in groups 1, 2,
D-block elements tend to have 2 valence electrons because the s-block before them is full. Those s-block electrons are the valence electrons.
However, it is possible for the first 5 d-block electrons to be valence electrons.