Arrangement of Electrons in Atoms

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Chapter 4

• Arrangement of Electrons in Atoms

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Section 4-2Quantum Mechanical Model of the Atom

• Totally different approach.
• Emphasizes the wave properties of an electron.
• Electron bound to the nucleus similar to a
  standing wave.

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• IMPORTANT Scientists
• de Broglie
• Heisenberg
• Schrödinger

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For the Electron in a Hydrogen Atom

• Similar situation of only certain allowable
  Electron Waves.
• Modeled by Schrödinger

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de Broglie

• Proposed that electrons have dual
• wave-particle nature.

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Heisenberg Uncertainty Principle

• For a particle so small such as an electron,
• the uncertainties become so significant that
  we can not know the exact motion of the electron
  as it moves around the nucleus.

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Schrodinger Wave Equation

• When eqn is anaylzed, there are many solutions.
• Each soln is a wave function, ?, characterized
  by a particular value of E and is often called an
  orbital.

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• Orbitals describe volumes of space
• where the electron is likely to be
• found.
• Orbitals are not orbits/not detailed
• pathways.

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Describes the probability of finding an electron
at a given place around the nucleus. Describes
possible cloud shapes that electrons might
occupy.
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Orbitals

• 3-D region around the nucleus that indicates the
  probable location of an electron.
• Electron Clouds
• 1) Electrons are in atomic orbitals
• 2) Orbitals have Quantized Energies.

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Quantum Numbers

• 4 different numbers that specify the properties
  of atomic orbitals and the properties of
  electrons in orbitals.

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Quantum Numbers (QN)

• 1. Principal QN (n 1, 2, 3, . . .)
• - related to size and energy of the orbital.
• - Shell Number
• - larger n, then higher energy

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2. Angular Momentum Quantum Number

• (l 0 to n ? 1)
• - relates to shape of the orbital.
• - Subshell
• l 0 s subshell
• l 1 p subshell
• l 2 d subshell
• l 3 f subshell

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3. Magnetic Quantum Number

• (ml l to ?l)
• - relates to orientation of the orbital in
  space relative to other orbitals.

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Two Representations of the Hydrogen 1s, 2s, and
3s Orbitals
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The Boundary Surface Representations of All Three
2p Orbitals
No 1p orbital. Each orbital has 2 lobes a node
at the nuclues.
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The Boundary Surfaces of All of the 3d Orbitals
No 1d or 2d orbitals
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Representation of the 4f Orbitals in Terms of
Their Boundary Surfaces
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4. Electron Spin Quantum Number

• (ms 1/2, ?1/2)
• - relates to the spin states of the electrons.

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Location Energy of Electrons

• Designated by the
• Shell ( n 1, 2, 3,)
• Subshell
• Orbital

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Subshells

• s subshell ? contains one s orbital
• p subshell ? contains three p orbitals
• d subshell ? contains five d orbitals
• f subshell ? contains seven f orbitals

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Atomic Orbitals

• Contain a maximum of 2 electrons
• Subshells of Orbitals of electrons
• s 1 2
• p 3 6
• d 5 10
• f 7 14