Orbital Notation and Electron Configuration

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Orbital Notation andElectron Configuration

• October 20th

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Distance From The Nucleus

• Called the Principle Quantum Number (n)
• Describes the principle energy level
• n 1, 2, 3

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Shape of the Orbital

• Described by Orbital quantum number (l)
• Tells you the shape of the orbital the electron
  is in
• Is it an s, p, d, or f orbital?

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Position in 3D Space

• Described by Magnetic Quantum Number (m)
• Indicated the position of the orbital around the
  3 axes (x, y, z)

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Electrons Spin

• The direction of the electrons spin is described
  by the spin quantum number
• Electrons can be either up or down
• When electrons are part of a pair, they must spin
  in opposite directions

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Pauli Exclusion Principle

• No two electrons in the same atom can have the
  same four quantum numbers (the same description)
• No two electrons can have the same address
• Electrons are repulsed by each other, so they
  cannot live together Hence makes sense they have
  opposite spins!

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Review Of Energy Levels

• n 1
• s orbital (2 electrons)
• n 2
• s orbital (2 electrons)
• p orbital (6 electrons)
• n 3
• s orbital (2 electrons)
• p orbital (6 electrons)
• d orbital (10 electrons)
• n 4
• s orbital (2 electrons)
• p orbital (6 electrons)
• d orbital (10 electrons)
• f orbital (14 electrons)

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3 Rules for Electron Configuration

1. Aufbau Principle - electrons occupy the orbitals
   of lowest energy first
2. Pauli Exclusion Principle - no two electrons can
   have the same address(same 4 quantum s)
3. Hunds Rule - Electrons try to occupy different
   orbitals before pairing up

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Orbital Notationorder in which electrons are
filled
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The Order in which orbitals fill
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Orbital Notation
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Arrangement of Electrons in Atoms

• Each orbital can be assigned no more than 2
  electrons!
• Each orbital can hold a pair of electrons per
  orientation
• s 1 orientation(pair) 2 electrons
• p 3 orientations 6 electrons
• d 5 orientations 10 electrons
• f 7 orientations 14 electrons

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Orbital Diagram
_____ 1s _____ _____ _____ _____
2s 2px 2py
2pz _____ _____ _____ _____ _____ _____
_____ _____ _____ 3s
3px 3py 3pz
3d _____ _____ _____ _____ _____
_____ _____ _____ _____ 4s
4px 4py 4pz
4d _____ _____ _____ _____
_____ _____ _____ _____ _____
5s 5px 5py 5pz
5d _____ 6s
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How Orbitals Fill.

• _____
• 1s
• _____ _____ _____ _____
• 2s 2px 2py 2pz
• _____ _____ _____ _____
• 3s 3px 3py 3pz
  

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Electron Configuration Strontium
_____ 1s _____ _____ _____ _____
2s 2px 2py
2pz _____ _____ _____ _____ _____ _____
_____ _____ _____ 3s
3px 3py 3pz
3d _____ _____ _____ _____ _____
_____ _____ _____ _____ 4s
4px 4py 4pz
4d _____ _____ _____ _____
_____ _____ _____ _____ _____
5s 5px 5py 5pz
5d _____ 6s
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Valence electrons are electrons in the outermost
energy level of an atom.
Example Sulfur
_____ 1s _____ _____ _____ _____
2s 2px 2py
2pz _____ _____ _____ _____
3s 3px 3py 3pz

Valence electrons
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Practice on your own!

• Draw the orbital diagram for Calcium
• Draw the orbital diagram for Silicon

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Electron Configuration
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Electron Configuration

• Fortunately! Its like orbital diagrams but
  without drawing the orbitals
• Fill electrons into lower energy levels first
• Follow order of filling
• Remember how many electrons each level can hold
  s holds 2, p holds 6, d 10, f 14

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Examples

• Helium 1s2
• Boron 1s22s22p1
• Magnesium 1s22s22p63s2
• Bromine 1s22s22p63s23p64s23d104p5

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Practice on your own!
Hydrogen Sodium Magnesium Chlorine Argon Arsenic

• 1s1
• 1s22s22p63s1
• 1s22s22p63s2
• 1s22s22p63s23p5
• 1s22s22p63s23p6
• 1s22s22p63s23p64s23d104p3

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Octet Rule

• Octet rule - all elements want to have a full set
  of valence electrons
• Atoms will lose or gain electrons in trying to
  achieve a full octet

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Octet Rule
Octet Rule states that atoms will gain or lose
electrons to achieve a full outermost energy
level. This is usually 8 electrons (s2 p6).
Example Oxygen
_____ 1s _____ _____ _____ _____
2s 2px 2py 2pz
O