Chp 6 Liquids and Solids [COMPLETE] Flashcards
what are the intramolecular forces?
metallic bonding, ion-ion bonding, and covalent network bonding
what are the intermolecular forces, from strongest to weakest?
hydrogen bonding, dipole-dipole, dispersion forces (london or van der waals)
what is hydrogen bonding?
when a molecule has a hydrogen atom that is bonded to a nitrogen, oxygen or fluorine (H-N, H-O, H-F). partial neg connected to partial pos charge
why is hydrogen bonding very strong?
N, O, and F are so much larger and more electronegative than H, tightly knit
what are dipole dipole forces similar to?
hydrogen bonding; have the partial neg connect to partial pos, just not on N, O, or F molecules
what are dipole dipole forces?
when a molecule w a polar bond (significant electronegativity diff) causes one atom to have partial neg and the other atom to have partial pos charge, and cluster w another similar molecule; aka the forces between these two clusters
what do dipole dipole forces only apply to?
polar, non-ionic molecules that are not H bonded to N, O, or F
what are dispersion forces?
forces that occur in all molecules in which temporary partial pos and partial neg attractions can exist
what forces will a non polar molecule have that does not have hydrogen bonding or dipole dipole forces?
dispersion forces
if two molecules exist with the same intermolecular forces, the larger molecule (higher molecular weight) will have what?
stronger force and a higher boiling point
what are intermolecular forces responsible for?
a molecules boiling point
definition: intermolecular forces
forces that attract molecules to each other
what are the characteristics of a strong intermolecular force?
high boiling point, high viscosity, high surface tension, low vapor pressure
↑ intermolecular force = _ boiling point? _ heat of vaporization?
↑ boiling point, ↑ heat of vaporization
↑ intermolecular force = _ viscosity?
↑ viscosity
what causes surface tension?
H2O molecules at the top of a body of water experience downward and side-to-side attraction from neighboring molecules; creates a thin film on water surface
↑ intermolecular force = _ surface tension?
↑ surface tension
when does boiling occur?
when vapor pressure equals or exceeds atmospheric pressure
↑ intermolecular force = _ vapor pressure?
↓ vapor pressure
↓ atmospheric pressure = _ boiling point?
↓ boiling point
↑ atmospheric pressure = _ boiling point?
↑ boiling point
what are the four classes of solids?
metallic solids, ionic solids, covalent-network solids, and molecular solids
what are metallic solids held together by and what are its properties?
held by a delocalized “sea” of shared electrons, flowing around nuclei “islands”; properties include conductive, variable hardness, and high melting point
what are ionic solids held together by and what are its properties?
held by the strong attraction between cations and anions; properties non-conductive, hard, brittle and high melting point
what are covalent-network solids held together by and what are its properties?
held by an extended network of covalent bonds; properties include non-conductive, hard, high melting point
what are molecular solids held together by and what are its properties?
held by the intermolecular forces; properties include non-conductive, soft, low melting point
what are unit cells?
small repeating units stacked over and over that make up an entire solid
how many atoms are in a simple cubic cell?
1
how many atoms are in a body-centered cubic?
2
how many atoms are in a face-centered cubic?
4
solid —> liquid
fusion
liquid —> gas
vaporization
solid —> gas
sublimation
fusion, vaporization, and sublimation all:
consume heat (endothermic +∆H)
create disorder (positive entropy +∆S)
gas —> liquid
condensation
liquid —> solid
crystallization
gas —> solid
deposition
condensation, crystallization, and deposition all:
produce heat (exothermic -∆H)
create order (negative entropy -∆S)
↑ boiling point = _ vapor pressure
↓ vapor pressure
↑ vapor pressure = _ volatility
↑ volatility
↑ vapor pressure = _ temperature
↑ temperature
what is a phase diagram?
graphical way to show pressures and temperatures at which a substance will exist as either a solid, liquid, or gas, or in some kind of equilibrium
what is the critical point of a phase diagram?
upper right point; beyond this, liquids and gases are indistinguishable
what is the triple point of a phase diagram?
left middle point; point where all three phases are in equilibrium
what does the line of equilibrium between solid and liquid signify:
where solid/liquid can exist at the same time and where phase change occurs
what phase change occurs when you increase the temperature at a high enough pressure?
fusion (solid to liquid)
what phase change occurs if you increase the temperature but the pressure is not high enough?
sublimation (solid to gas)
how long does the solid/liquid line continue on?
forever
(most compounds)
gas (add pressure) ___ liquid (add pressure) ___ solid
–>, –>
(for water)
gas (add pressure) ___ liquid ___ (add pressure) solid
–>, <–
in what state is water more dense?
as a liquid
why is water is more dense as a liquid than as a solid?
lattice arrangement of water molecules causes more space to be between them
how is water’s phase diagram different from a normal one?
solid/liquid line leans to the left; negative slope; meaning if temperature is low enough and you add pressure, gas can go straight to solid without becoming liquid and adding more pressure will turn solid to liquid (adding more pressure would not turn a solid to liquid in a normal phase diagram)
what does the negative slope of the water phase diagram mean?
the liquid phase of water is more dense than solid
what is distillation?
process by which miscible liquids are separated by boiling point
what is filtration?
separation of solids from liquids by pouring through a filter
what is decantation?
separation of liquids from solids by pouring the liquid carefully off the top
describe a chemical compound
a substance composed of different elements in fixed proportions
what is a pure element?
a substance that cannot be decomposed into simpler species
