1. Recap What does “ground state” refer to? A. A hydrogen atom
B. Lowest energy state of an atom
C. Highest energy state of an atom
D. When the atom is on the ground
B. Lowest energy state of an atom

2. Recap How does an electron become “excited?”
A. The atom it resides in reacts with another atom
B. It absorbs energy and jumps shells
C. It absorbs specific amounts of energy and jumps shells
D. When it sees a particle of opposite charge
C. It absorbs specific amounts of energy and jumps shells

3. Recap What is a photon? A. A packet of light B. An excited proton
C. An excited electron
A Chinese wonton stuffed with Vietnamese noodles
A. A packet of light

4. White Light Spectrum
Emission Spectrum of H

5. Recap What is an orbital?
A. The path an electron takes around the nucleus
B. Lobes
C. The shape of the nucleus
D. Mathematical description (probability) of where to find an electron in an atom
D. Mathematical description (probability) of where to find an electron in an atom

6. Electron Configuration
Where are the electrons?

8. Energy Level Diagram
Shell 4 3
orbitals 2
subshells 1

9. Rules to follow when filling orbitals:
Fill orbitals from lowest to highest energy (Aufbau Principle)
Place one electron in each orbital of a sub-shell
When each orbital of a sub-shell has one electron, go back and pair the electrons (Hund’s Rule)
If two electrons are in a orbital, they must have opposite spin (Pauli Exclusion Principle)

10. electron-electron repulsion
These rules ensure that the electron configuration gives the ___________ energy, most __________ atom by reducing ________________________________.
lowest
stable
electron-electron repulsion

13. More About Shells
Shell 4 3 2 1
1s22s22p63s23p64s23d104p6 2 8 8 18

14. How can you write the electron configuration without the energy level diagram???

15. Aufbau

17. 1s 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 5d 6p 6d 7s 4f 5f

19. Ar:
1s2
2s2
2p6
3s2
3p6
3p5
3p3
3p1
3p2
3p4

20. Ga:
1s2
2s2
2p6
3s2
3p6
4s2
3d10
4p1

21. Ag:
1s2
2s2
2p6
3s2
3p6
4s2
3d10
4p6
5s2
4d9

22. Rn:
1s2
2s2
2p6
3s2
3p6
4s2
3d10
4p6
5s2
4d10
5p6
6s2
4f14
5d10
6p6

24. K
[Ar]
1s2 2s2 2p6 3s2 3p6
4s1
1s2 2s2 2p6 3s2 3p6 Ti
[Ar]
4s2 3d2
1s2 2s2 2p6 3s2 3p6 Ni
[Ar]
4s2 3d8
1s2 2s2 2p6 3s2 3p6 Ga
[Ar]
4s2 3d10 4p1
1s2 2s2 2p6 3s2 3p6 Kr
[Ar]
4s2 3d10 4p6 Ar

25. [Ar]
4s2 3d 5

26. Example: Write the electron configuration for Ga using core notation.
Closest previous noble gas element: ______
Core notation:___________________ Ar
[Ar] 4s23d104p1

27. Practice: Write the electron configuration for the following elements.
Zn _______________________________
K ________________________________
Kr _______________________________

28. There are 2 exceptions to the electron configuration of elements up to Kr:

29. What you would expect for Cr

30. In Reality

31. What you would expect for Cu

32. In Reality

33. Reason: ½ filled and completely filled subshells are more stable than partially filled subshells, and in Cr and Cu, it only takes one electron to achieve this stability in the 3d subshell
Expected
Reality Cr
[Ar] 4s23d4
[Ar] 4s13d5 Cu
[Ar] 4s23d9
[Ar] 4s13d10