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Warm Up 9/20

Warm Up 9/20. Draw the Bohr Model for Aluminum What is the difference between a hypothesis and a theory?. The Quantum Mechanical Model. Chemistry. Bohr’s Model. Bohr energized hydrogen electrons (1 e - per atom) Energized electrons jumped certain distances from the nucleus.

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Warm Up 9/20

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  1. Warm Up 9/20 • Draw the Bohr Model for Aluminum • What is the difference between a hypothesis and a theory?

  2. The Quantum Mechanical Model Chemistry

  3. Bohr’s Model • Bohr energized hydrogen electrons (1 e- per atom) • Energized electrons jumped certain distances from the nucleus

  4. Bohr’s Model • Bohr saw 4 colors • Each color has a specific wavelength

  5. Bohr’s Model • Each wavelength corresponds to a distance from the nucleus • These distances are called “shells” or “energy levels”

  6. Bohr was wrong • While Bohr’s theory worked for hydrogen, it could not be applied to any other element because they all have more than one electron

  7. Werner Heisenberg • 1927, Germany • Heisenberg Uncertainty Principle = It is impossible to determine simultaneously both position and velocity off an electron or any other particle

  8. Heisenberg’s Uncertainty Principle • It’s impossible to determine where any one electron is at any point in time. • Scientists talk about probabilities of electrons locations (electronic cloud).

  9. Erwin Schrödinger • Physicist from Austria • Late 1920’s • Wrote an equation to describe the probable location of an electron

  10. Quantum Mechanical Model • Current Electron Theory • Created by Schrödinger • Involves Quantum Numbers • Can be shown using Electron Configurations (ex: 1s22s22p5)

  11. Quantum Numbers • Each electron is located in an energy level (n), which is within a sub-level with a shape (l).

  12. Quantum Numbers • A sub-level is made of orbitals. Different electrons within the same sub-level will have a different orientation (ml) depending on the orbitals orientation within the sub-level. • Each orbital can have 2 electrons max, but they have opposite spin (ms)

  13. Quantum Mechanical Model • Electrons are arranged into Energy Levels or Shells (1, 2, 3, 4, …). • The “Principal Quantum Number” (symbolized by n) indicates the main energy level occupied by the electron

  14. Quantum Mechanical Model • Energy Levels contain sub-levels (s, p, d, f) • The “Azimuthal or Angular Momentum Quantum Number” (symbolized by l) indicates the shape of the sub-level

  15. NRG Sub-level “s”Azimuthal Quantum Number 0 “s” sub-level • l = 0 • Sphere shape • Contains 2 e- • One Orbital

  16. NRG Sub-level “p”Azimuthal Quantum Number 1 “p” sub-level l = 1 Contains maximum 6 e- 3 orbitals

  17. NRG Sub-level “d”Azimuthal Quantum Number 2 “d” sub-level l = 2 Maximum 10 e- 5 orbitals

  18. NRG Sub-level “f”Azimuthal Quantum Number 3 “f” sub-level l= 3 Maximum 14 e- 7 orbitals

  19. Quantum Numbers • Magnetic Quantum Number (ml) indicates the orientation of an orbital around the nucleus • For example, the sub-level “p” is composed of 3 different orbitals (px, py, and pz) • Scientists use the values -1, 0, and +1 to tell the orbitals apart.

  20. Practice with Magnetic Quantum Numbers • What would be the magnetic quantum number used for the s sub-level? • What would be the magnetic quantum numbers used for the d sub-level?

  21. Spin Quantum Number,ms • A maximum of 2 electrons can fit into each orbital. BUT electrons don’t like each other (repel) • 2 spins = +1/2 (up) and -1/2 (down)

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