1. The Bohr Model, Wave Model, and Quantum Model
Sections
The Bohr Model, Wave Model, and Quantum Model

2. Objectives Analyze Bohr’s model of the electron
Describe the wave behavior of matter
Arrange electrons in an atom
Identify energy levels
Apply Heisenberg’s Uncertainty Principle
Describe the quantum mechanical model

3. Key Terms Ground state Excited states Matter waves momentum
Uncertainty principle
Wave functions
Probability density
Electron density
Orbitals
Electron shell
subshell

4. Niels Bohr, 1913 Proposed quantum model for H atom
Proposed H atom has only certain allowable energy states
Lowest state= ground state
Gaining energy = excited state

5. Niels Bohr, 1913
Electrons move in certain, specific, circular orbitals
Energy added to atom e- moves to higher energy level
Electron in “excited state” drops to a lower energy orbit emits a photon

7. Niels Bohr, 1913 Problems with Bohr’s model Only explained H
Electrons move as waves

8. De Broglie, 1924
Electrons, like light, have particle-wave dual nature

9. Heisenberg Uncertainty Principle, 1927
Fundamentally impossible to know precisely both the velocity AND position of a particle at the same time.
x  h
4mv

10. Assignment
De Broglie and Heisenberg Worksheet

11. Quantum Mechanical Model
1926
Schrödinger
Limited electrons to only certain energy levels
Atomic orbital: 3 dimensional area around nucleus; 90 % PROBABLE location of electron

12. Principal quantum number, n
Principal energy levels (shells)
Positive integers greater than 0
Relative to sizes and energies

13. Azimuthal quantum number, l
Energy sublevels (subshells)
Integers from 0 to n-1 for each n value
Defines the shape of orbital

14. Continued
l is designated by a letter:
Value of l 1 2 3
Letter s p d f

15. Magnetic Quantum Number, ml
Orbitals
Has integer values between –l and l, including zero
Describes orientation of orbital in space

16. Spin Magnetic Quantum Number, ms
Electrons
2 per orbital
-1/2 or +1/2
Represents the direction on electron’s spin

17. All Together… Each electron can be described using: n,l,ml,ms OR
Principal energy level, sublevel, orbital, spin

18. s orbital

19. p orbitals

20. d orbitals

21. f orbitals

22. Assignment
Quantum Model Worksheet