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

2. The Quantum Model of the Atom
Louis De Broglie (1924)
Suggested that electrons can have a dual wave-particle nature
Confirmed by experiments which showed electrons can undergo diffraction and interference
Dr Quantum - Double Slit Experiment - YouTube

3. The Heisenberg Uncertainty Principle
Werner Heisenberg (1927)
It is impossible to determine simultaneously the position and velocity of an electron
Electrons are detected by interaction with photons (photons have similar energy to electrons and thus alter the position of electrons)
Quantum Mechanics: The Uncertainty Principle - YouTube

4. The Schrodinger Wave Equation
Erwin Schrodinger (1926)
Developed an equation which treated electrons as waves.
Solutions to the equation (wave functions) give the probability of finding an electron in a given location around the nucleus
Atomic orbital – region of space in which an electron is most likely to be found

5. Atomic Orbitals and Quantum Numbers
Quantum Numbers –used to describe the properties of atomic orbitals and the properties of electrons in those orbitals
Three quantum numbers are derived from the Schrodinger equation and indicate energy level, orbital shape, and orbital orientation
One quantum number describes the spin of an electron in an atomic orbital

6. Principal Quantum Number
Principal Quantum Number (n)
Indicates main energy level occupied by an electron.
As “n” increases, energy and distance from the nucleus increases

7. Angular Momentum Quantum Number
Angular momentum quantum number (l)
Indicates the shape of the orbital
Within each energy level, there are sublevels.
# sublevels = n
Orbital Letter Designations and l values l
Letter s 1 p 2 d 3 f

8. Shapes of Orbitals
s – orbital
p - orbitals

9. Shapes of Orbitals
d - orbitals

10. Shapes of Orbitals
f - orbitals

11. Magnetic Quantum Number
Magnetic Quantum Number (m)
Indicates the orientation of the orbital around the nucleus
Magnetic quantum number n l m 1 2
-1, 0, +1 3
-2, -1, 0, +1, +2 4
-3, -2, -1, 0, +1, +2, +3

12. Spin Quantum Number Spin Quantum Number
Indicates the spin of an electron in an orbital
Value = + 1/2 or -1/2
An orbital can hold a maximum of 2 electrons, which must have opposite spin.

13. Atomic Orbitals

14. Orbital Energy Diagram