The Quantum Model of the Atom

Chapter 4.2

Objectives:1. Discuss Louis de Broglie’s role in the development of the

quantum model of the atom.

2. Compare and contrast the Bohr model and the quantum model of the atom.

3. Explain how the Heisenberg uncertainty principle and the Schrodinger wave equation led to the idea of atomic orbitals.

4. List the four quantum numbers, and describe their significance.

5. Relate the number of sublevels corresponding to each of an atom’s main energy levels, the number of orbitals per sublevel, and the number of orbitals per main energy level.

Quantum Model of the Atom

DeBroglie

• electrons confined to certain space around nucleus at specific frequencies – energy levels

Heisenberg Uncertainty Principle• it is impossible to determine simultaneously both the position

and velocity of an electron

Schrodinger Wave Equation

• Treated electrons as waves

• With uncertainty principle – gave probability of finding an electron in certain regions

These 3-D regions are called - Orbitals

Quantum Theory

Describes mathematically the wave properties of electrons

Quantum Numbers – specify the properties of atomic orbitals and electrons in them

1. Principal quantum number (n) main energy level occupied by electrons

2. Angular Momentum (l)

• indicates the shape of the orbital

l = 0 1 2 3

s p d f

3. Magnetic (m)

• orientation of orbital around nucleus

m =-2,-1,0,+1,+2

m =-1,0,+1

m = 0

4. Spin Quantum Number ( +1/2, -1/2)

Indicates the two fundamental spin states of electron in an orbital

Single orbital can hold a maximum of 2 electrons