Lectures 1-4 Flashcards
LDF (London Dispersion Forces)
The force of attraction that arises as a result of temporary dipoles induced in the atoms of molecules
Hydrogen Bonding
A type of dipole-dipole interaction between the hydrogen atoms in a polar bond and an unshared electron pair of an element that is very electronegative; must be N, O, or F
Dipole-Dipole
Forces that occur between polar molecules
Ion-Dipole
Experienced by ions interacting with polar molecules in solution
Dipole-Induced Dipole Forces
Exists when a polar molecule induces a dipole on a nonpolar molecule due to proximity
Polarizability
Measure of ease with which electron charge density is distorted by an external electric field: reflects the ability for which a dipole can be induced
Adhesion
The ability to “stick” to things (like glass) other than itself
Cohesion
The ability to “stick” to itself
Viscosity
Resistance to flow exhibited by all liquids and gases
Surface Tension
Resistance of a liquid to increase in its surface area
Capillary Rise
Spontaneous rising of a liquid up a narrow tube
Triple point
The point on the phase diagram at which all three states of matter exist (and are in equilibrium)
Critical Point
The point on the phase diagram where the liquid and gaseous states are indistinguishable
Supercritical Fluid
Any substance at a temperature and pressure above its critical point
Molecular Solids
Solids (like ice) that are held together by intermolecular forces like LDF, Dipole-Dipole, Ion-Dipole, etc.; low melting point and nonconducting
Ionic Solids
Ionic bonds (oppositely charged ions) hold the solid in a regular three dimensional arrangement; high melting point, brittle, and hard
Covalent Network
A solid consists of atoms held together in large networks or chains by covalent bonding (electrons pairs are shared between atoms); high melting point, hard, and nonconducting
Metallic Solids
Similar to a covalent network, but with metals; variable hardness and melting, and high conductivity
Allotrope
Some solid substances can exist in more than one form (diamond, coal, graphite)
Solubility
The maximum amount of a solute (dissolved substance) that is dissolved in a solvent (the substance dissolving dissolved substance) at a given temperature
Saturated Solution
Contains the maximum amount of dissolved solute for a given amount of solvent at a specific temperature and pressure
Supersaturated Solution
Contains more dissolved solute than a saturated solution (more than the solvent is able to handle)
Dilute Solutions
Contains less dissolved solute than a saturated solution (could dissolve more solute if needed)
Strong Electrolyte
Complete dissociated into ions in a solution
Weak Electrolytes
Produce few ions and do not dissociate completely in a solution
Nonelectrolyte
Will not produce ions
Miscible
Two liquids which share intermolecular forces and are able to mix with one another
Immiscible
Two liquids that do not have intermolecular forces in common and will not mix with one another
Q = mc∆T
m = mass
c = specific heat
∆t = change in temperature
Used to solve when temperature is changing
Q = n∆H
n = moles
∆H = enthalpy
Used to solve when temperature is stable
Clausius Clapeyron
ln(P2/P1)=(-∆Hvap/R)(1/T2-1/T1)
R = 8.314 J/mol K
Pressure is directly related to temperature
Unit Cells
Finding out the number of atoms in a unit cell:
d = (# atoms / unit cell) (MW/Na)(1/Vc)
d = density
# atoms / unit cell = number of atoms per unit cell
MW = molecular weight
Na = Avogadro’s number (6.022 X 10^23)
1/Vc = Reciprocal of the volume
Unit Cells (continued)
Simple Cubic: One cell on each corner (there is 1 atom total); edge length formula: a = 2r
Body Centered Cubic: One cell on each corner and anther right in the middle (there are 2 atoms total); edge length formula: a = 4r/sqrt3
Face Centered Cubic: One cell on each corner and one in the middle of each face (there are 4 atoms total); edge length formula: a = 2r(sqrt2)
Henry’s Law
C = kp
C = gas solubility (M)
P = partial pressure
K = Henry’s law constant
Normally asked to find k using this formula
