1. Quantum Model of the Atom
Electrons in Atoms
Quantum Model of the Atom

2. Electrons as Waves Louis de Broglie (1924)
Applied wave-particle theory to e-
e- exhibit wave properties
QUANTIZED WAVELENGTHS

3. Radial Distribution Curve
Quantum Mechanics
Orbital (“electron cloud”)
Region in space where there is 90% probability of finding an e-
Orbital
Radial Distribution Curve

4. Quantum Numbers Four Quantum Numbers:
Specify the “address” of each electron in an atom
UPPER LEVEL

5. Quantum Numbers 1. Principal Quantum Number ( n ) Energy level
Size of the orbital

6. Quantum Numbers f d s p 2. Angular Momentum Quantum # ( l )
Energy sublevel
Shape of the orbital f d s p

7. C. Quantum Numbers 3. Magnetic Quantum Number ( ml )
Orientation of orbital
Specifies the exact orbital within each sublevel

8. C. Quantum Numbers 4. Spin Quantum Number ( ms )
Electron spin  +½ or -½
An orbital can hold 2 electrons that spin in opposite directions.

9. Quantum Numbers 2s 2px 2py 2pz
Orbitals combine to form a spherical shape. 2s
2pz
2py
2px

10. Quantum Numbers Pauli Exclusion Principle
No two electrons in an atom can have the same 4 quantum numbers.
Each e- has a unique “address”:
1. Principal # 
2. Ang. Mom. # 
3. Magnetic # 
4. Spin # 
energy level
sublevel (s,p,d,f)
orbital
electron

11. Aufbau Principle
Electrons will fill the lowest energy level available (e- want to be as close to the nucleus as possible)
They must fill in order! Once a sublevel is full, then move to the next available sublevel.

13. Quantum Numbers px py pz