1. Orbitals and Quantum Numbers

2. Electron Orbitals
Describes the distribution of electron density in space
4 types: s, p, d, f

3. Three Rules for Filling Orbitals
Enter lowest energy level first (Aufbau Principle)
No more than two electrons per orbital (Pauli Exclusion Principle) – must have opposite spins
Maximize unpaired electrons (Hund’s Rule)
So what does it look like?
#16 on WS - Draw an orbital diagram for chlorine: 1s 2s 2p 3s 3p 4s 3d

4. Show me what you know!
Draw the orbital diagram for the electrons in calcium. Don’t forget to label the orbitals!

5. FIRST NUMBER Principle Quantum Number (n)
Relates to the size and energy of orbital
lower n: closer to the nucleus (on average), lower in energy

6. SECOND NUMBER Angular Momentum Quantum Number (l)
Defines the shape of an orbital
s sub-shell: l = 0
p sub-shell: l = 1
d sub-shell: l = 2
f sub-shell: l = 3

7. THIRD NUMBER Magnetic Quantum Number (ml)
ml = - l to +l
Relates to the orientation of the orbital in space

8. FOURTH NUMBER Electron Spin Quantum Number (ms)
ms = +1/2 or - 1/2
Indexes spin direction of an e- within an orbital

9. Quantum Numbers Summary
Written as: n, l, ml , ms
Example – brown WS #2:
Fill in the orbital notation, then write the four quantum numbers which describe the location of the highest energy (last) electron of the following elements:
2. Ni

10. Another Example Written as: n, l, ml , ms Example – brown WS #7:
Give the four quantum numbers which describe the location of each of the following:
7. The 4th electron in carbon

11. Show me what you know!
Draw the orbital diagram for the electrons in titanium AND write the quantum numbers for the last electron in titanium.