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27 Cards in this Set
- Front
- Back
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London Dispersion Forces consist primarily of what type of interaction?
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Induced dipole moment
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Do induced dipole moments depend on polarizability?
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Yes
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Why are induced dipole moments ALWAYS net attractive?
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Due to reinforcing nature of Coulombic attractions
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If two dipoles attract, what happens?
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Molecules come together, stabilize to induce a dipole-dipole interaction
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If two dipoles repel, what happens?
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The molecules drift apart. The reaction "washes out"
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Give the formula for the induced dipole at very close range
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u = Polarizability * E-Field
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As atomic radius increases, Polarizability does what?
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Increases
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List, from greatest relative energy to lowest relative energy, the 7 types of molecular interactions:
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Covalent
Ion/Ion Hydrogen Bond (8 - 20 KJ/mol) Ion/Dipole (15 KJ/mol)------There is overlap between these two Dipole/Dipole Dipole/Induced Dipole Induced Dipole/Induced Dipole |
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Which of the following types of interactions has higher relative energy? Covalent Bond or Hydrogen Bond
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Covalent Bond
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Which of the following types of interactions has higher relative energy? Ion/Ion or Dipole/Induced Dipole
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Ion/Ion
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Which of the following types of interactions has higher relative energy? Dipole/Dipole or Induced Dipole/ Induced Dipole
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Dipole/Dipole
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Which of the following types of interactions has higher relative energy? Ion/Dipole or Dipole/Induced Dipole
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Ion/Dipole
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Are hydrogen bonds direction?
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Yes, they match the orientation of the lone pair (Think VSEPR)
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Rules for ranking boiling point of a molecules:
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1. Ionic interactions then H-Bonds have the highest boiling point
2. Dipole/Dipole then Dipole/Ionic have slightly lower boiling points 3. Dispersion (induced dipoles) have the lowest boiling points (though can be quite significant if the molecules are large) |
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Rank the boiling point of the following molecules: NaCl and H2
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NaCl is highest because it is ionic.
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Rank the boiling point of the following molecules: C2H4 and H2
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Both molecules are non-polar. However, because C2H4 has many more e-, it has a higher boiling point than H2.
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Rank the boiling point of the following molecules: H2 and CH3OH
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The Lewis structure of CH3OH predicts a hydrogen bond between the molecules, thus CH3OH has a higher boiling point.
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Rank the boiling point of the following molecules: O2 and O3
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O3 has a dipole whereas O2 does not. Because None of the listed rules apply to O2 (while one does to O3), O2 has the lowest boiling point.
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What are the three types of lattice structures when using a cubic lattice?
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Primitive, Body Centered, Face Centered
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Structure of a Primitive lattice
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Atoms at the corners of the cube. Total of 1 atom per unit cell
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Structure of a Face Centered lattice
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Atoms at the corners and center of each face. 4 Atoms per unit cell
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Structure of a Body Centered lattice
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Atoms at the corners, one atom at the center of the cube. 2 Atoms per unit cell.
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Volume of a Primitive lattice in terms of atomic radius:
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Volume = 8 (r^3)
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Volume of a Face Centered lattice in terms of atomic radius:
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Volume = (8^(3/2))*(r^3)
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Volume of a Body Centered lattice in terms of atomic radius:
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Volume = ((16/3)^(3/2))*(r^3)
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Calculate packing efficiency for any given lattice structure (Primitive, Face Centered, Body Centered)
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Packing efficiency = # atoms * Volume atom / Volume of unit cell
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Bragg's Law (diffraction of x-ray's through a metal)
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nλ = 2dsin(Θ)
n is an integer Use in conjunction with: tan(2Θ) = X/D X = distance from central bright spot to first order bright spot D = distance from metal to screen d = length of one side of the unit cell of the metal |
