1. Atomic Orbitals
The energy levels of electrons are labeled by principal quantum numbers (n)
Each energy sublevel corresponds to an orbital of a different shape, which describes where the electron is likely to be found.

2. Atomic Orbitals

3. Shapes and Orientations of Orbitals
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Shapes and Orientations of Orbitals

4. 1s Orbital Sphere around the nucleus
The one tells you that the electron is in the orbital closest to the nucleus
S tells you about the shape

5. 2s Orbital
Similar to 1s except the electron is most likely in the region farther from the nucleus

6. p Orbitals
At the first energy level there is only the 1s orbital, after the second energy level there are 2p orbitals
Look like dumbbells
In the three directions

10. Remember…. MAX NUMBER OF ELECTRONS IN AN ENERGY LEVEL
MAX # OF ELECTRONS 1 2 8 3 18 4 32 5 50

11. Electron Configuration
A detailed way of showing the order in which electrons fill in around the nucleus

12. Electron Configuration Symbols
# of e- in sub level
Electron Configuration Symbols
1s 2
Energy Level
Sub Level
(s, p, d, f )

13. We must follow 3 rules… Aufbau priciple
Electrons occupy energy levels with lowest energy first.

14. Pauli exclusion principle
If 2 electrons occupy the same energy level they must have opposite spins.

15. Hund’s rule…
Electrons that occupy orbitals of the same energy will have the maximum number of electrons with the same spin. 2p

16. To start we will use orbital filling diagrams to help us with electron configurations….
Example
Boron- has 5 electrons

17. Periodic table arrangement
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the quantum theory helps to explain the structure of the periodic table.
n - 1 indicates that the d subshell in period 4 actually starts at 3 (4 - 1 = 3).