1. Electrons in atoms

2. Models of atomic structure:
Dalton: Tiny, hard spheres
JJ Thompson: Plum Pudding model
Rutherford
Bohr: Planetary model
ALL WRONG
The quantum mechanical model and electron configuration can tell us nearly exactly where to find any electron in the atom

3. Quantum Mechanical Model
Quantum: energy required to move an electron to the next energy level
Einstein knew that electrons were jumping energy levels because when he electrified them, light was given off. This indicated that the electrons were giving off energy, or jumping back to the ground state
The amount of energy required to jump energy levels is quantized, or measurable
This amount of energy and the jumps can be observed with a spectroscope
Elemental finger print = emission spectrum!!!

4. What does the quantum mechanical model look like?
QUANTUM NUMBERS
Principle quantum number (n) = Energy levels (1-7)
Second Quantum number (l) = Sublevels (s, p, d, f)
s = sphere
p= dumbbell
d= clover
f= flower

5. Magnetic quantum number (ml)
Orbitals (2 electrons in each one) (orientations)
s has 1, can hold max 2 electrons
p has 3, can hold max 6 electrons
d has 5, can hold max 10 electrons
f has 7, can hold max 14 electrons
Think ‘seats on a bus’

6. Spin quantum number (m s): ½, -1/2
Electrons repel one another, sooooo
To get 2 ‘in the same seat on the bus’ they must have opposite spin. This creates a slightly attractive force
No 2 electrons can have the same 4 quantum numbers. This is a ‘map’ to the specific electron

7. Why clouds? Electrons are small and move very, very quickly.
Think of a photograph and a videotape:
If you take a photograph can you know the exact location of an electron? YES! Can you know the electron’s speed? NO!
If you take a video, can you know the exact location of the electron? NO! Can you know the speed? YES!
Heisenberg Uncertainty Principal: it is impossible to know the exact location and speed of an electron at any given time
We use ‘probability clouds’ to describe location. These are where the electron is most likely to be located.

8. Homework
Pg 366, 1-4
Pg 386, 20-24