Solids, Liquids, and Gases Notes

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Solids, Liquids, and Gases Notes
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I. How do solids and liquids differ from gases?

• Solids
• intermolecular forces are sufficiently strong
  relative to kinetic energy
• molecules are virtually locked in place often in
  a very orderly pattern (crystalline structures)
• definite volume and shape

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• Liquids
• attractive intermolecular forces between
  molecules is comparable to kinetic energies of
  molecules
• molecules are held in close proximity, but still
  move in a rather chaotic motion
• definite volume but no definite shape
• considered a fluid

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• Gases
• molecules/particles in chaotic motion
• average kinetic energy is greater than the
  attractive forces between molecules
• have no definite volume or shape
• considered a fluid

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• II. Intermolecular Forces (IM) - These are weak
  forces that exist between molecules and are
  responsible for the fact that the substance can
  exist as a liquid (and/or solid). Molecules of
  gases have little to no intermolecular forces
  (which is why gases have no definite shape or
  volume). Dipole-dipole IM forces, London
  dispersion, and hydrogen bonding are
  intermolecular forces.

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• IntrAmolecular Forces are the bonds or forces
  within the atoms of a molecule the two bonds
  connecting two hydrogen atoms to an atom of
  oxygen in water are intrAmolecular forces. The
  force holding water molecules together so they
  dont evaporate are intErmolecular forces and are
  about l/6 to l/l0th as strong as single covalent
  bonds. Covalent, ionic, and metallic bonding are
  intramolecular forces. Metallic bonding is the
  strongest of the three.

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Intramolecular Force
Draw this picture in your notes!
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Dipole Dipole Forces
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Hydrogen Bonding
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• Practice Problems True or False
• 1. Gases have a definite volume. True or False?
• 2. Solids are considered fluids. True or False?
• 3. Dipole-dipole, London dispersion, and
  hydrogen bonding are intermolecular forces. True
  or false?
• 4. Intermolecular forces describe the forces of
  attraction between one molecule and another
  molecule. True or false?
• 5. Intramolecular forces describe the bonds
  between atoms within a molecule. True or false?
• 6. Gases have little to no intermolecular forces
  so they have no definite shape or volume. True
  or false?
• 7. Covalent, ionic, and metallic bonding are the
  three intramolecular forces. True or False?
• 8. Ionic bonds are the strongest of the three
  intramolecular forces. True or False?

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III. Phase Changes

• 1. vaporization (?H) liquid to gas
• 2. condensation (-?H) gas ? liquid
• 3. sublimation (?H) solid ? gas
• 4. deposition (-?H) gas ? solid
• 5. melting (?H) solid ? liquid
• 6. freezing (-?H) liquid ? solid
• Phase changes involve the breaking and forming of
  intermolecular forces.

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• The phase changes that involve
  the breaking of intermolecular forces
  of attraction include
• melting, vaporization, and
  sublimation
• These require an input of energy to overcome the
  attractive forces between the particles of the
  substance.

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• The phase changes that involve
  the forming of intermolecular forces
  of attraction include
• freezing, condensation, and
  deposition
• These release energy as the particles adopt a
  lower-energy conformation.

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• The strength of the intermolecular attractions
  between molecules, and therefore the amount of
  energy required to overcome these attractive
  forces (as well as the amount of energy released
  when the attractions are formed) depends on the
  molecular properties of the substance. Generally,
  the more polar a molecule is, the stronger the
  attractive forces between molecules are.

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• Phase Diagrams a graph of pressure VS
  temperature that shows the conditions under which
  the phases of a substance exist.
• Phase Diagram for Water

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Phase Diagram for Carbon Dioxide
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