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DIFFERENT? Gas, Liquid or Solid? UNIT 3 Day 6 What are we going to - - PowerPoint PPT Presentation
DIFFERENT? Gas, Liquid or Solid? UNIT 3 Day 6 What are we going to - - PowerPoint PPT Presentation
Sparks CH301 WHY IS EVERYTHING SO DIFFERENT? Gas, Liquid or Solid? UNIT 3 Day 6 What are we going to learn today? MO of large molecules Recognize different molecules have different physical properties Classify Intermolecular Forces POLL:
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Most molecules have
- A. An even number of electrons
- B. An odd number of electrons
- C. Equal chance of even or odd
POLL: CLICKER QUESTION
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Most molecules are
- A. diamagnetic
- B. paramagnetic
- C. Evenly split between the two
POLL: CLICKER QUESTION
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How is this tool used.. Calculate the lowest energy geometry; Where is the electron density What if it is a complicated molecule with lots of atoms It is hard to relate the MO to AO None the less the MOs are useful
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Other way we use MO, just the pi electrons
VB for sigma bonds
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MO for the pi bond Where are the electrons? Delocalized around the molecule
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Typical MO for organic molecule
Almost always diamagnetic HOMO/LUMO Energy gap Light absorption Dyes – homo lumo gap is the color that is absorbed, gaps as a function of structure
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MO picture of Ethanol
VSEPR and VB to get visual image Predict Polar just from ball and stick
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Chemical Composition & Shape
Physical Properties? GAS? or LIQUID?
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Types of Forces
Intramolecular Forces: forces that hold together an individual molecule
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Types of Forces
Intermolecular Forces: forces between different molecules
e.g., forces between: separate CO2 molecules in CO2 separate H2O molecules in H2O
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Thought Question!
H2O(g) + 927 kJ 2H(g) + O(g) H2O(l) + 40.7 kJ H2O(g) For water, which are stronger: A.The intermolecular forces. B.The intramolecular forces.
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What dominates the interaction in condensed phases?
What are these forces? Classify forces. Define IMF. REMEMBER TAPE REMEMBER CHARGED ROD and LIQUIDS
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INTERMOLECULAR FORCES
DOMINATE FORCE IN CHEMISTRY – COULOMBIC
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INTERMOLECULAR FORCES
DOMINATE FORCE IN CHEMISTRY – COULOMBIC
Qualify the word “intermolecular”
Boling Point: 1413 °C
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INTERMOLECULAR FORCES
CONDENSED PHASE – BUT NOT IONIC MOLECULAR CONDENSDED PHASE: MOLECULAR LIQUID OR MOLECULAR SOLIDS “PARTICLE IS A MOLECULE”
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Intermolecular forces are based on attraction of
- pposite charges.
Electrostatic forces
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In covalent molecules, intermolecular forces are based on the molecule polarity.
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REMEMBER: A molecule which is polar overall will have a NET DIPOLE. From now on we refer to this type of molecule as a DIPOLE.
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INTERMOLECULAR FORCES: dipole-dipole
Attractive force between partial negative end of
- ne molecule and
partial positive end of another molecule. Strength depends on distance and dipole moment. E 1 r3
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POLL: CLICKER QUESTION CLICKER QUESTION ALL NONPOLAR COMPOUNDS ARE GASES: A) TRUE B) FALSE
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