1. LT1: Electron Arrangement (Ch. 5)

2. How do fireworks work?

3. Rutherford’s Model of the Atom
Contributions
Problems
Nucleus: Explains where positive protons and where the mass of the atom is found
Electron Arrangement: electrons are outside the nucleus flying in empty space
Doesn’t explain electron arrangement or reactivity/properties of atoms

4. Characteristics of Waves

5. Electromagnetic Radiation

6. What is the relationship between wavelength and frequency of EM waves
What is the relationship between wavelength and frequency of EM waves? How is Energy related?

7. What does amplitude tell you about the wave?

8. Why did the wave model of light need a revision?
It didn’t explain why only certain colors are emitted from heated objects.
It didn’t explain why metals emit electrons when struck by certain types of light.

9. Planck and Quantum
Matter can only gain a CERTAIN AMOUNT OF ENERGY= QUANTUM
The colors emitted from an object when heated is directly related to the Quantum.

10. Is light a wave or a particle?

11. Why do we see colors from neon signs?
What do you think the color depends on?

12. Why do some atoms emit green and others emit red?

13. Explanation--- remember ROYGBIV
Atoms are struck by Energy (light, flame, electricity).
The electrons are excited out of ground state to excited state where they are unstable.
As electrons fall back to ground state they give off the energy they absorbed as LIGHT.
The color depends on the quantum absorbed.
Higher quantum= BIV
Lower quantum= ROY

14. Atomic emission spectrum= set of frequencies an atom gives off- fingerprint for an atom

15. Bohr’s Model ENERGY LEVELS:
Contributions
Visual
ENERGY LEVELS:
Electrons move in circular patterns around the nucleus like planets around the sun.
Closer to the nucleus= lower energy
Further from nucleus= higher energy
QUANTUM NUMBER:
n=1 closest to nucleus
Movement from n= 2 to n=1 results in a photon

16. Problems with Bohr Model
Doesn’t explain electron movement within Energy Levels correctly
Electrons DO NOT orbit like planets around the sun
Only works for Hydrogen

17. Accepted theory today: Quantum Mechanical Model of the Atom http://www
Electrons are treated like waves
Electrons have certain ENERGY VALUES which dictate their distance from the nucleus
Lower energy ___________ the nucleus
Higher energy __________ the nucleus
DOES NOT explain electron path as “orbiting like planets around the sun”

18. De Broglie and the Quantum Mechanical Model
Wave-like motion of electrons: all moving particles have wave-like motion that restricts how much energy the electrons can absorb and emit (QUANTUM)

19. Schrodinger and the Quantum Mechanical Model
Atomic Orbitals: 3D space electrons are likely to be found
SHAPES electron fly in

20. Quantum Mechanical Model continued
Principal Quantum Number (n)= #’s assigned that correlates with:
Size
Speed of electron
Distance from the nucleus
Amount of energy electron has
COLOR AND LABEL A PERIODIC TABLE

21. Atomic Orbitals

22. Quantum Mechanical Model cont.
Principle Energy Level= correlates with the distance from the nucleus and amount of energy electron has.
Energy sublevels= the number of orbitals in each energy level

23. s Sphere 1 2 p Dumbbell 3 6 d Clover 5 10 f Complex 7 14
Type of sublevel
Shape
# of orbitals (configurations)
Max # of electrons s
Sphere 1 2 p
Dumbbell 3 6 d
Clover 5 10 f
Complex 7 14

24. Can you fill in the rest by looking at a Periodic table?
Energy level or Principal Quantum Number
Sublevels
Max # of electrons 1 1s 2
2s, 2p 8 3
3s, 3p, 3d 18 4 5 6 7

25. Heisenberg Uncertainty Principle

26. Electron Configuration- Main Idea: A set of three rules can be used to determine electron arrangement in an atom.
Aufbau principle
Electrons occupy lowest energy level first.
Pauli Exclusion Principle
Electron have opposite spins if they are in the same orbital.
Hund’s Rule
Electrons occupy each orbital before pairing.

27. Practice Electron configuration of Sodium: Orbital Notation of Sodium:
Noble Gas Configuration of Sodium:

28. Exceptions to the Rules
Many transition metals don’t follow the rules
Copper and Chromium are common examples