1. Electron Configuration and Orbital Diagrams

2. Electron Configuration
Shows the arrangement of electrons in an atom.

3. Orbital Diagram Another way of writing the electron configuration.
An orbital is a potential space for an electron.
Atoms can have many potential orbitals.
Orbitals are represented by boxes grouped by sublevel with small arrows indicating the electrons.

4. Pauli Exclusion Principle
An atomic orbital can hold a maximum of 2 electrons and those 2 electrons must have opposite spins.
An electron is represented by an arrow.
Spin is represented by the arrow facing up or down.

5. Hydrogen Electron Configuration: Orbital Diagram
Hydrogen can only fill the first Principal Energy Level labeled “1”.
Hydrogen can only fill the first orbital labeled “s”.
Orbital Diagram
Hydrogen has an atomic number of 1, so it has 1 electron available to place in the orbital diagram.

6. Helium Electron Configuration: Orbital Diagram
Helium can only fill the first Principal Energy Level labeled “1”.
Helium can only fill the first sublevel labeled “s”.
Orbital Diagram
Helium has an atomic number of 2, so it has 2 electrons available to place in the orbital diagram.

7. Aufbau Principle Electrons are placed in the lowest energy
level first.

8. Lithium Electron Configuration: Orbital Diagram
Lithium can fill the first Principal Energy Level labeled “1” and the second PEL labeled “2”.
Lithium can only fill the first sublevel labeled “s”.
Orbital Diagram
Lithium has an atomic number of 3, so it has 3 electrons available to place in the orbital diagram.

9. Beryllium Electron Configuration: Orbital Diagram Be: 1s22s2
Beryllium can fill the first Principal Energy Level labeled “1” and the second PEL labeled “2”.
Beryllium can only fill the first sublevel labeled “s”.
Orbital Diagram
Beryllium has an atomic number of 4, so it has 4 electrons available to place in the orbital diagram.
Be: 1s22s2

10. Boron Electron Configuration: Orbital Diagram B: 1s22s22p1
Boron can fill the first Principal Energy Level labeled “1” and the second PEL labeled “2”.
Boron can fill the first sublevel labeled “s” and the second sublevel labeled “p”.
Orbital Diagram
Boron has an atomic number of 5, so it has 5 electrons available to place in the orbital diagram.
B: 1s22s22p1

11. Hund’s Rule
When filling sublevels other than s, electrons are placed in individual orbitals first, before they are paired up.
They must be placed singly before doubly.

12. Carbon Electron Configuration: Orbital Diagram C: 1s22s22p2
Carbon can fill the first Principal Energy Level labeled “1” and the second PEL labeled “2”.
Carbon can fill the first sublevel labeled “s” and the second sublevel labeled “p”.
Orbital Diagram
Carbon has an atomic number of 6, so it has 6 electrons available to place in the orbital diagram.
C: 1s22s22p2

13. Nitrogen Electron Configuration: Orbital Diagram N: 1s22s22p3
Nitrogen can fill the first Principal Energy Level labeled “1” and the second PEL labeled “2”.
Nitrogen can fill the first sublevel labeled “s” and the second sublevel labeled “p”.
Orbital Diagram
Nitrogen has an atomic number of 7, so it has 7 electrons available to place in the orbital diagram.
N: 1s22s22p3

14. Oxygen Electron Configuration: Orbital Diagram O: 1s22s22p4
Oxygen can fill the first Principal Energy Level labeled “1” and the second PEL labeled “2”.
Oxygen can fill the first sublevel labeled “s” and the second sublevel labeled “p”.
Orbital Diagram
Oxygen has an atomic number of 8, so it has 8 electrons available to place in the orbital diagram.
O: 1s22s22p4

15. Organization of Orbitals
The periodic table has organized the orbitals.
The “s”
orbitals
The “p”
The “d”
The “f” orbitals

16. Organization of Orbitals
The first row is Principal Energy Level 1.
The second row is Principal Energy Level 2.
Principal
Energy Level
3 begins in
the 3rd row.
Energy Level 4 begins
in the 4th row.

17. and so the pattern continues…

18. Sublevels The “s” sublevel can hold 2 electrons.
The “p” sublevel can hold 6 electrons.
2 electrons in each of the 3 orbitals (x, y, z)
The “d” sublevel can hold 10 electrons.
2 electrons in each of the 5 orbitals.
The “f” sublevel can hold 14 electrons.
2 electrons in each of the 7 orbitals.

19. Practice Problems
Write the electron configuration and the orbital diagram for Fluorine.

20. Practice Problems
Write the electron configuration and the orbital diagram for Magnesium.

21. Practice Problems
Write the electron configuration and the orbital diagram for Sulfur.

22. Practice Problems
Write the electron configuration and the orbital diagram for Potassium.

23. Noble Gas Configuration
Is an abbreviated version of electron configuration.
Uses the noble gas that precedes the element, then the electron configuration that comes after the noble gas.
Used for elements with larger atomic numbers.
Example:
Nitrogen

24. Noble Gas Configuration
Is important because it shows the valence electrons present in an atom.
Nitrogen has an atomic number of 7. It has 7 total electrons. If you look at the electron configuration, you can count 7 electrons.

25. Noble Gas Configuration
But if you look at the Noble Gas Configuration, you can count 5 electrons.
These 5 electrons are the valence electrons, the electrons found in the outermost energy level. These are the electrons available for bonding.

26. Valence Electrons The periodic table organizes valence electrons.
The number
of valence
electrons
are written
above each
column in
the diagram.

27. Practice Problems
Write the noble gas configuration and the orbital diagram for Iron.

28. Practice Problems
Write the noble gas configuration and the orbital diagram for Tin.