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Quantum Model

Quantum Model. Essential Question. How can the quantum model be used to determine the relative positions of electrons?. Why don’t we use the Bohr atom as our current model??. Limitations of the Bohr Atom. Doesn’t explain WHY: Energy levels are quantized (WAIT, WHAT IS QUANTIZED?)

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Quantum Model

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  1. Quantum Model

  2. Essential Question • How can the quantum model be used to determine the relative positions of electrons?

  3. Why don’t we use the Bohr atom as our current model??

  4. Limitations of the Bohr Atom • Doesn’t explain WHY: • Energy levels are quantized (WAIT, WHAT IS QUANTIZED?) • e- can only have certain energies • Cannot accurately calculate spectral lines of large atoms

  5. Louis de Broglie

  6. DeBroglie cont. • Explains why energy is quantized in the atom • Can only have complete wavelengths, no partial

  7. Heisenberg Uncertainty Principle • Impossible to know both the exact position and exact momentum of an electron at the same time • Reasoning: • Light used to see an e- would change its position • e- can’t be in specified orbits

  8. Schrödinger’s Work • Developed a wave function to properties of the e- wave to the probability of finding the e- in a given area • Complex math used to determine many part of the quantum atom

  9. Schrödinger’s Work Cont. Probability of finding an electron Most probable place to find an e- Distance from the nucleus

  10. Schrödinger’s Cat • Big Bang Clip http://www.youtube.com/watch?v=oerZnryFxX0 • Quantum Mechanics is not a reality, but a probability of a reality

  11. Orbitals https://www.youtube.com/watch?v=K-jNgq16jEY

  12. Quantum Atom • Current model of the atom • Electrons exist as wavelike particles • e- in various probability shells, NOT circular orbits • Within those energy shell they exist within sub-orbitals • Each e- is defined by a set of quantum numbers

  13. Quantum Numbers • 4 different types • n, l, ml, ms • Together they make a set which describes a particular e-

  14. Quantum Number Sets: • n, l, ml, ms • Describe 1 e- • Unique to all e- in the atom

  15. Principle Quantum Number (n) • States the particular energy level (shell) • Possible Values: • n=1,2,3….∞

  16. Sublevel/Orbital Shapes

  17. Indicates the orbital shape, sub-shell Possible Values: 0 to (n-1) ℓ = 0 → s orbital ℓ = 1 → p orbital ℓ = 2 → d orbital ℓ = 3 → f orbital Angular Momentum Quantum Number (l) sphere Dumbbell Clover Leaf Flower (and other odd shapes)

  18. Magnetic Quantum Number (ml) • Specifies the 3-D orientation of the sub-orbital • Possible Values • - l…0…+l • For Example: 3 Possible ways to orient the ‘p’ orbital

  19. Spin Quantum Number (ms) • Tells the direction the e- is spinning • Up or down • Possible Values: • ms = +1/2 or -1/2

  20. Summary: The Four Quantum Numbers

  21. Quantum Possibilities Chart

  22. What is wrong with each of the following? 1. N=3 l=2 Ml=-3 Ms=+1/2 2. N=3 l=3 Ml=-3 Ms=+1/2 3. N=4 l=3 Ml= 0 Ms=+1 4. N=2 l=2 Ml=-3 Ms= -1/2

  23. What is the purpose of quantum #’s? • Energy level • Shape • 3-D organization • Magnetic Spin • https://www.youtube.com/watch?v=4WR8Qvsv70s

  24. If there is an electron in a p-orbital of the 2rd energy level, list all possible sets of quantum numbers which could apply to it. • n= • l= • ml = • ms=

  25. Take out your periodic table!

  26. Orbital Diagram!

  27. How do e- fill orbitals in an atom? • Fill based upon 3 rules/principles • Pauli Exclusion Principle • Aufbau Principle • Hund’s Rule

  28. Pauli Exclusion Principle • No 2 e- can have the same 4 quantum #’s • If n, l, and ml are the same, need opposite spins (ms) • Means only 2 e- per orbital

  29. Aufbau Principle • e- fill lowest energy orbitals first then fill higher energy orbitals • Not always in order of energy levels because of orbital overlap

  30. Orbital Overlap • Orbitals become large and overlap each other Orbitals fill in this order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s…

  31. Hund’s Rule • e- spread out amongst the orbitals before pairing up Think: Seats on a school bus Example: Don’t fill like this: Fill like this:

  32. Let’s Practice!

  33. Noble Gas configuration • An abbreviated configuration to show the position of the electrons. • How to do it: start at the element at hand, the trace backwards to the nearest noble gas (group 18). • Put the noble gas in brackets, then continue with the abbreviation.

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