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 are and where the majority of the mass of the atom is found
Electron Arrangement: electrons are outside the nucleus flying in empty space
Doesn’t explain electron arrangement, why electrons aren’t pulled into nucleus, or reactivity/properties of atoms (related to electron arrangement)

4. EM radiation has Characteristics of Waves
Frequency= number of waves
passing a point in a given
amount of time.

5. 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?

6. Electromagnetic Radiation- waves created by electric and magnetic fields moving at right angles to each other.

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. 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

13. Atomic emission spectrum= set of frequencies an atom gives off- continuous color is broken down with a spectroscope--fingerprint for an atom

14. LAB Question: Why does copper emit green and strontium emit red?
Use the terms: quantum, ground state, excited state, energy level, frequency, wavelength, and electron.

15. Quantum Mechanical Model- describes electron arrangement in Energy levels and Orbitals
Quantum Mechanical Model answers:
How do electrons move around the nucleus of an atom?
How does ENERGY determine arrangement?
What are ENERGY LEVELS?
What are ORBITALS?

16. 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

17. 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

18. 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”

19. 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)

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

21. 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

22. Atomic Orbitals

23. Quantum Mechanical Model cont.
Principle Energy Level= correlates with the distance from the nucleus and amount of energy electron has.
Electrons fill lowest energy levels first
Energy sublevels= the number of orbitals in each energy level
Electrons fill lowest energy
orbitals first

24. 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

25. 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
2,6 = 8 3
3s, 3p, 3d
2,6,10 = 18 4 5 6 7

26. Heisenberg Uncertainty Principle

27. 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.

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

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