1. chemistry

2. Electron Configurations
5.2
Electron Configurations
The ways in which electrons are arranged in various orbitals around the nuclei of atoms are called electron configurations.
Three rules—the aufbau principle, the Pauli exclusion principle, and Hund’s rule—tell you how to find the electron configurations of atoms.

3. Electron Configurations
5.2
Electron Configurations
Aufbau Principle
According to the aufbau principle, electrons occupy the orbitals of lowest energy first. In the aufbau diagram below, each box represents an atomic orbital.
This aufbau diagram shows the energy levels of the various atomic orbitals. Orbitals of greater energy are higher on the diagram. Using Tables Which is of higher energy, a 4d or a 5s orbital?

4. 5.2 Filling Order 7i 6h 7h 5g 6g 7g 4f 5f 6f 7f 3d 4d 5d 6d 7d 2p 3p1s 2s 3s 4s 5s 6s 7s

5. Blocks on the Periodic Table
5.2
Blocks on the Periodic Table

6. Sublevels/Orbitals/Electrons
5.2
Sublevels/Orbitals/Electrons
Sublevel
# of Orbitals
Max. # of Electrons s 1 2 p 3 6 d 5 10 f 7 14

7. Electron Configurations
5.2
Electron Configurations
Pauli Exclusion Principle
According to the Pauli exclusion principle, an atomic orbital may describe at most two electrons. To occupy the same orbital, two electrons must have opposite spins; that is, the electron spins must be paired.

8. Electron Configurations
5.2
Electron Configurations
Hund’s Rule
Hund’s rule states that electrons occupy orbitals of the same energy in a way that makes the number of electrons with the same spin direction as large as possible.

9. Electron Configuration
5.2
Electron Configuration
# of Electrons
Energy Level
Orbital

10. Orbital Filling (Orbital Notation)
5.2
Orbital Filling (Orbital Notation)
↿⇂ ↿⇂ ↿⇂ ↿ ↿
1s s 2px 2py 2pz
This is the orbital notation for oxygen
Hund’s Rule

11. Orbital Filling (Notation)/Electron Configurations
5.2
Orbital Filling (Notation)/Electron Configurations
Orbital Filling Diagram
Hund’s Rule

13. for Conceptual Problem 1.1
Problem Solving 5.9 Solve Problem 9 with the help of an interactive guided tutorial.

14. Exceptional Electron Configurations
5.2
Exceptional Electron Configurations
Some actual electron configurations differ from those assigned using the aufbau principle because half-filled sublevels are more stable than other configurations and filled sublevels are even more stable than half filled sublevels.

15. Exceptional Electron Configurations
5.2
Exceptional Electron Configurations
Exceptions to the aufbau principle are due to subtle electron-electron interactions in orbitals with very similar energies.
In the 4th Period Chromium and Copper have an electron configuration that is an exception to the aufbau principle.
Copper is a good conductor of electricity and is commonly used in electrical wiring.

16. 5.2 Section Quiz.
5.2.

17. 5.2 Section Quiz.
1. Identify the element that corresponds to the following electron configuration: 1s22s22p5. F Cl Ne O

18. 5.2 Section Quiz.
2. Write the electron configuration for the atom N.
1s22s22p5
1s22s22p3
1s22s1p2
1s22s22p1

19. 5.2 Section Quiz.
3. The electron configurations for some elements differ from those predicted by the aufbau principle because the
the lowest energy level is completely filled.
none of the energy levels are completely filled.
half-filled sublevels are less stable than filled energy levels.
half-filled sublevels are more stable than some other arrangements.

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