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Warm Up9/20. 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 Up9/20

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Warm up 9 20

Warm Up9/20

  • Draw the Bohr Model for Aluminum

  • What is the difference between a hypothesis and a theory?

The quantum mechanical model

The Quantum Mechanical Model


Bohr s model

Bohr’s Model

  • Bohr energized hydrogen electrons

    (1 e- per atom)

  • Energized electrons jumped certain distances from the nucleus

Bohr s model1

Bohr’s Model

  • Bohr saw 4 colors

  • Each color has a specific wavelength

Bohr s model2

Bohr’s Model

  • Each wavelength corresponds to a distance from the nucleus

  • These distances are called “shells” or “energy levels”

Bohr was wrong

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

Werner heisenberg

Werner Heisenberg

  • 1927, Germany

  • Heisenberg Uncertainty Principle = It is impossible to determine simultaneously both position and velocity off an electron or any other particle

Heisenberg s uncertainty principle

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).

Erwin schr dinger

Erwin Schrödinger

  • Physicist from Austria

  • Late 1920’s

  • Wrote an equation to describe the probable location of an electron

Quantum mechanical model

Quantum Mechanical Model

  • Current Electron Theory

  • Created by Schrödinger

  • Involves Quantum Numbers

  • Can be shown using Electron Configurations (ex: 1s22s22p5)

Quantum numbers

Quantum Numbers

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

Quantum numbers1

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)

Quantum mechanical model1

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

Quantum mechanical model2

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

Nrg sub level s azimuthal quantum number 0

NRG Sub-level “s”Azimuthal Quantum Number 0

“s” sub-level

  • l = 0

  • Sphere shape

  • Contains 2 e-

  • One Orbital

Nrg sub level p azimuthal quantum number 1

NRG Sub-level “p”Azimuthal Quantum Number 1

“p” sub-level

l = 1

Contains maximum 6 e-

3 orbitals

Nrg sub level d azimuthal quantum number 2

NRG Sub-level “d”Azimuthal Quantum Number 2

“d” sub-level

l = 2

Maximum 10 e-

5 orbitals

Nrg sub level f azimuthal quantum number 3

NRG Sub-level “f”Azimuthal Quantum Number 3

“f” sub-level

l= 3

Maximum 14 e-

7 orbitals

Quantum numbers2

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.

Practice with magnetic quantum numbers

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?

Spin quantum number m s

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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