LEC 14: Intermolecular Forces, Liquids, and Solids Flashcards
attraction between molecules
intermolecular force
much weaker than ionic or covalent bonds
intermolecular forces
when a substance melts or boils, intermolecular forces are _______
broken
when a substances condenses, intermolecular forces are ______
formed
______ reflect intermolecular force strength
- boiling points
- melting point
high boiling point indicates _______ attractive forces
strong
______ melting point indicates strong attractive forces
high
intermolecular forces that exist between neutral molecules
van der Waals forces
van der Waals forces include:
- london dispersion forces
- dipole-dipole forces
- hydrogen-bonding forces
interactions important in solutions
ion-dipole
physical properties of substances are understood in terms of _______
kinetic-molecular theory
highly compressible and assume the shape and volume of their container
gas
_____ are far apart and do not interact much with one another
gas molecules
almost incompressible, assume the shape but not the volume of the container
liquid
liquid molecules are held together _____ than gas molecules but not so _____ that the molecules cannot slide past each other
- more closely
- rigidly
incompressible and have a definite shape and volume
soild
solid molecules are _____ together
packed closely
solid molecules are _____packed that they cannot easily slide past each other
so rigidly
condensed phases
- solid
- liquid
solids with highly ordered structures
crystalline
converting gas into a liquid or solid requires the molecules to get ____ to each other
closer
converting a solid into a liquid or gas requires the molecules to move _____ apart
further
forces holding solids and liquids together
intermolecular forces
there are forces _____ molecules
between
solid to liquid/gas conversion can be accomplished by ____ the pressure on the gas
heating or reducing
gas to liquid or solid conversion can be accomplished by _____ the gas
cooling or compressing
weakest of all intermolecular forces
london-dispersion forces
ease with which an distribution can be deformed
polarizability
the ____ the molecule, the more polarizable it is
larger
london disperion forces increase as ______ increases
molecular weight
london dispersion forces depend on the ____ of the molecule
shape
the greater the surface area available for contact, the ____ the dispersion forces
greater
london dispersion forces between spherical molecules are _____ than those between more cylindrically shaped molecules
smaller
exist between neutral polar molecules
dipole-dipole forces
polar molecules _____ each other
attract
special type of intermolecular attraction
hydrogen bonding
interaction between an ion and the partial charge on the end of a polar molecule/dipole
ion-dipole
resistance of a liquid to flow
viscosity
amount of energy required to increase the surface area of a liquid by a unit amount
surface tension
intermolecular forces that bind molecules to one another
cohesive forces
intermolecular forces that bind molecules to a surface
adhesive forces
rise of liquids up very narrow tubes
capillary action
changes of state
phase changes
solid to gas
sublimation
solid to liquid
melting or fusion
liquid to gas
vaporization
gas to liquid
desposition
gas to liquid
condensation
liquid to solid
freezing
enthalpy of fusion
heat of fusion
how do liquids flow
by sliding molecules over one another
viscosity depends on:
- attractive forces between molecules
- tendency of molecules to become entangled
- temperature
the stronger the intermolecular forces, the ____ the viscosity
higher
viscosity ____ as molecules become entangled with one another
increases
viscosity usually _____ with an increase in temperature
decreases
______ (in liquid) are equally attracted to their neighbors
bulk molecules
surface molecules are only attracted ____ towards the bulk molecules
inward
surface molecules are packed ____ than bulk molelcules
more closely
bulk molecules causes the liquid to behave as if it had a _____
skin
stronger intermolecular forces causes _____ surface tension
higher
water has a ____ surface tension
high
hg has an _____ surface tension
even higher
there are very strong ____ bonds between Hg atoms
metallic
shape of the liquid surface
meniscus
if _____ forces are greater than ____ forces, the meniscus is u-shaped
- adhesive forces
- cohesive forces
if _____ forces are greater than ______ forces, the meniscus is curved downwards
- cohesive forces
- adhesive forces
rise of liquids up very narrow tubes
capillary action
the liquid climbs up (in capillary action) until adhesive and cohesive forces are ______
balanced by gravity
endothermic phase changes:
- sublimation
- melting or fusion
- vaporization
exothermic phase changes:
- freezing
- deposition
- condensation
Δ H > 0
endothermic or exothermic
endothermic
Δ H < 0
endothermic or exotehrmic
exothermic
the heat of fusion is less than the heat of ______
vaporization
it takes _____ energy to completely separate molecules than to partially separate them
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