III' Quantum Model of the Atom

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III. Quantum Model of the Atom

• Electrons in Atoms

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A. Electrons as Waves

• Louis de Broglie (1924)

• If radiation energy can behave as a stream of
• particles could matter show properties of a
  wave?
• Characteristic ? of an e- or other particle
  depends on
• ? h
• mv (momentum)
• This equation predicts that all moving objects
  have
• wavelike behavior

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A. Electrons as Waves
QUANTIZED WAVELENGTHS
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A. Electrons as Waves
EVIDENCE DIFFRACTION PATTERNS
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B. Quantum Mechanics

• Heisenberg Uncertainty Principle
• Impossible to know both the velocity and position
  of an electron at the same time

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B. Quantum Mechanics

• Orbital (electron cloud)
• Region in space where there is 90 probability of
  finding an e-

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B. Quantum Mechanics

• Orbitals
• s p
• d

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B. Quantum Mechanics

• Orbitals
• f

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C. Quantum Numbers

• Four Quantum Numbers
• Specify the address of each electron in an atom

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C. Quantum Numbers

• 1. Principal Quantum Number ( n )
• Energy level
• Size of the orbital
• n2 of orbitals in the energy level

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C. Quantum Numbers

• 2. Angular Momentum Quantum ( l )
• Energy sublevel
• Shape of the orbital

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C. Quantum Numbers

• n of sublevels per level
• n2 of orbitals per level
• Sublevel sets 1 s, 3 p, 5 d, 7 f

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C. Quantum Numbers
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C. Quantum Numbers

• 3. Magnetic Quantum Number ( ml )
• Orientation of orbital
• Specifies the exact orbitalwithin each sublevel

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C. Quantum Numbers
px
py
pz
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C. Quantum Numbers

• Orbitals combine to form a spherical shape.

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C. Quantum Numbers

• 4. Spin Quantum Number ( ms )
• Electron spin ? ½ or -½
• An orbital can hold 2 electrons that spin in
  opposite directions.

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C. Quantum Numbers

• Pauli Exclusion Principle
• No two electrons in an atom can have the same 4
  quantum numbers.
• Each e- has a unique address

1. Principal ? 2. Ang. Mom. ? 3. Magnetic
? 4. Spin ?
energy level sublevel (s,p,d,f) orbital electron
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C. Quantum Numbers
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Feeling overwhelmed?
Read Section 7.5!