Electronic Configuration Chemical Bonding Coordination

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Electronic ConfigurationChemical
BondingCoordination
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Electronic Configuration of the Elements

• www.nutrisci.wisc.edu/NS623/electronic.pdf
• What determines how electrons are distributed?
• Pauli Exclusion Principle
• Hunds Rule
• Good web site http//www.science.uwaterloo.ca/cc
  hieh/cact/c120/eleconfg.html

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Transition Elements
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Information on Transition Elementsor Why do we
care?

• http//library.thinkquest.org/3659/pertable/tramet
  al.html

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Oxidation of Iron

• Fe 2 Fe 3
• Ferrous Ferric
• Reduced Oxidized
• Reduction is the gain of electrons
• Oxidation is the loss of electrons

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Bonding in minerals

• Ionic
• Covalent
• Metallic
• Van der Waals
• Polar

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Ionic Bonding

• NaCl (halite or rock salt)
• Na and Cl- have noble gas configuration
• Electrostatic attraction bonds them together
• Minerals with ionic bonds have moderate H and G,
  have high melting points and are poor conductors
  of electricity and heat
• Strength is proportional to the electronic
  attraction
• Bond is non-directional

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Covalent

• Sharing of electrons
• Strongest of chemical bonds
• Do not yield ions in solution
• Bonds are directional
• Example diamond C

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Si-O bond

• Is about 50 covalent and 50 ionic
• Electronegativitypower of an atom to attract.
  Compounds made of elements with very different
  values of electronegativity are more ionic than
  compounds made of elemts clost to each other in
  electronegativity

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y 1 - exp(-0.25 x2) (Pauling, 1948)
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Metallic Bond

• Many electrons owe no allegiance to any
  particular nucleus and are free to drift
• Good conductors
• Usually low hardness and melting points
• Examples include native metals such as Cu, Ag,
  and Au
• Minerals may have qualities of several types of
  bonds galena ionic and metallic

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Van der Waals

• Dipoles of molecules
• Usually found in gases and liquids, rare in
  minerals
• Example is graphite C

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Polar Bonding or Hydrogen Bonding
Examples include micas
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Coordination Number C.N.

• of anions that can fit around a cation
• NaCl 6
• CaF2 8

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Radius Ratio

• This is the ratio of the radius of the cation to
  that of the anion
• This ratio usually determines the CN of the cation

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Coordination Number vs Radius Ratio
Make sure you remember to give examples on the
board
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Lets calculate one of the radius ratios

• Use triangular coordination
• Handout or on board!

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Some words you need to know

• CN4 tetrahedral
• CN6 octahedral
• CN8 cubic

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Paulings Rules

• http//www.tulane.edu/sanelson/eens211/paulingsru
  les.htm