1. Lecture 5.3 Aufbau Diagrams

2. Aufbau Diagram Boxes
Orbitals are hard to draw and the Aufbau Diagram is an easier way to show electron location, by using sets of boxes
Each box can hold up to 2 e-
s orbital – 1 box – total # of 2 e-
p orbital-3 boxes –total # of 6e-
d orbital-5 boxes – total # of 10 e-
f orbital -7 boxes – total # of 14 e-

3. Orbital Names of Elements in Principal Energy Level 1- 7 (Rows in the T)
2e- 6e- 10e- 14e- PEL 1: 1s PEL 2: 2s 2p PEL 3: 3s 3p 3d PEL 4: 4s 4p 4d 4f PEL 5: 5s 5p 5d 5f PEL 6: 6s 6p 6d 6f PEL 7: 7s 7p 7d 7f

4. Filling the Aufbau Diagram
Electrons try to be as close to
the protons in the nucleus
Therefore lowest to
energy levels close to the
nucleus fill first
Filling direction
Always fill from bottom
to top!!!

5. e- filling Guidelines 1. Find AN of element = # e-
Example: Sodium AN= ___ = ____ e-
2. Start with 1s, 2s, 2p….
3. Each box gets first 1 electon ↑, then when all suborbital have 1 e- per box, double up ↑↓
4. Single unmatched arrow has to be ↑

6. Practice the Aufbau Diagram for
Carbon
Sodium
Potassium

7. Overlapping Orbitals Higher energy levels have overlapping orbitals
Example: 4s fills before 3d….
Means 4s is energetically lower than 3d!!!

8. Set-up Aufbau Free-Hand
Draw x and y-axis
Mark s, p, d, f section on x-axis
Fill in s, p, d and f orbitals as lines (not boxes) – observe energy hierarchy of fold backs: 4s is energetically below 3d which is energeticall below 4p
Fill with arrows as learned
s: ___
p: ___ ___ ___
d: ___ ___ ___ ___ ___
f: ___ ___ ___ ___ ___ ___ ___

9. Understanding the Atom

10. Journal
Draw a free-hand Aufbau diagram for Chromium

11. Shorthand Electron Configurations
Translating the Aufbau diagram:
Example: 2p5
PEL orbital # e-
Means there are 5 e- in the 2p orbital

12. Find the element 2p5 2s2 1s2 Shorthand: 1s2 2s2 2p5 add up 2+2+5=9 e-

13. whi

14. Finding and Interpreting Valence e-
The outermost orbital is called the Valence electron (Ve-)orbital
Full Ve- orbital makes an element stable
Ve- of NG= 8 Add xs2 + xp6 = 8 Ve-(octet)
Ex: 1s2 2s2 2p6 3s2 3p3 = 5 Ve- of possible 8: element is unstable

15. Valence electrons Ve- are involved in Rx
Ve- are involved in emission spectra
Elements with half-filled Ve- orbitals are unstable and therefore react
Noble gasses have full Ve- orbitals and are therefore stable and do not react

16. [NG] shorthand e- Configuration
Noble gases: have full PEL Example: He: 1s2 Ne: Ar: Kr:

17. [NG] e-shorthand
Find the Noble gasses, use last Full shorthand: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3 He Ne Ar [NG] shorthand: [Ar] 4s2 3d10 4p3

18. Translate into [NG] e-shorthand Which element?

19. For Aluminum draw____ Bohr’s Model Aufbau diagram Orbital Model
Electron shorthand
[NG]shorthand

20. Using the Periodic Table and for e-Configuration and Aufbau

21. Practice
Use the periodic Table to write the e-shorthand for H Ag Ge O

22. Use your colored PT to write the full and [NG] shorthand for
Silver (Ag)
Rutherfordium (Ru)
Telurium (Te)

23. d- block variations
There is very little energy difference between 4s and 3d or 5s and 4d orbitals
d-block elements move/exchange electrons among s and d-orbitals for greater stability
Example Copper: Cu Cr
Normally: [Ar] 4s2 3d9 [Ar] 4s2 3d4
more stable: [Ar] 4s13d10 [Ar] 4s13d5