1. Quantum Theory

2. Quantum Theory Explains location of electrons Bohr vs. Quantum
Quantum Mechanical Model
Probability
Atomic Orbitals
Principal energy levels
Sublevels
Orbitals
Spin

3. Bohr Model
Electrons travel in definite orbits around the nucleus. Planetary Model
Electrons are located in energy levels
Electrons can not exist between energy levels
A quantum of energy is needed to move an electron from one level to the next higher level
Photon: a quantum of light energy released when an electron falls an energy level

4. Quantum of Energy
Energy is released or absorbed when an electron moves from one energy level to the next
Electrons move to higher energy levels when energy is absorbed
Electrons release the same quantum of energy as light when electrons fall into a lower energy level. We call this a photon of light.

5. Terms
Ground State- Lowest energy level occupied by an electron when an atom is in its most stable configuration
Excited State – Energy level occupied by an electron that is higher than the stable ground state energy level.

6. Quantum Mechanical Model
Electrons are located in energy levels.
The region is no longer a well defined orbit, but rather a 3D mathematical probability region outside the nucleus called an orbital
This 3D region is also known as the electron cloud. 90% of the time the electron is expected to be in this area.
A quantum of energy is still required to move an electron to a higher energy level and a photon of light is still released when the electron falls to a lower energy level

8. Light Both a wave and a particle
Amplitude: Height from the origin to the crest
Wave Length (λ ) : The distance between crests
Frequency (ν) : The number of wave cycles to pass a given point per unit of time. SI units are hertz.
Speed of light = wave length X frequency
c = λ ν c = 3.0 X 108 m/s

9. A Wave
                                                                           

10. Practice
What is the wavelength of radiation with a frequency of 1.50 x 1013 s-1?
Does this radiation have a longer or shorter wavelength than red light?

11. Max Planck
Related quantized light energy to the frequency of the light wave
E = hv; v is the frequency and h is Planck’s constant
H= x10-34 J-s

13. Atomic Emission Spectra
Every element ( in the gas or vapor state) emits light when heated
 Emission spectrum for each element is unique. Like a fingerprint.
Each line corresponds with one specific amount of energy being emitted
Video clips

15. Electron Configuration

16. Atomic Orbitals Electrons are located in atomic orbitals.
4 distribution levels of electrons around the nucleus
Principal energy level
Sublevel
Orbital
Spin

17. Principal Energy Levels
Defined by a principal quantum number (n)
n = 1, 2, 3, 4...
Distance from the nucleus increases as n increases
Energy increases as n increases

18. Sublevels
Within each principal energy level, the electrons occupy energy sublevels
 The number of sublevels is the same as the principal quantum number
n = 1 1s
n = 2 2s, 2p
n = 3 3s, 3p, 3d
n = 4 4s, 4p, 4d, 4f

19. Orbitals the region where electrons are likely to be found
 Orbitals are identified by letters and have different shapes
sublevel shape number
s orbitals spherical 1
p orbital dumbbell 3
d orbital cloverleaf 5  
f orbital 7

20. Practice How many orbitals are in the following sublevels?
3p sublevel:
2s sublevel:
4f sublevel:
4p sublevel:
3d sublevel:

21. Spin 2 electrons occupy each orbital
These 2 electrons have equal and opposite spins

22. Rule of Electron Configuration

23. Aufbau Principle Electrons enter orbitals of lowest energy first
S sublevel is lowest energy sublevel

24. Pauli Exclusion Principle
An orbital can hold no more than 2 electrons
Those electrons must have opposite spin

25. Hund’s Rule
When electrons occupy orbits of equal energy, one electron enters each orbital before the 2nd electron enters any orbital