ch. 11AAAAAAAAAAAAAAA Flashcards
What are intermolecular forces?
electrostatic forces that exist among particles, the state of matter depends on the magnitude of IMF and thermal energy
What are the characteristics of gas
low density, no definite shape, no definite volume, weak intermolecular forces
What is the major difference between liquid and solid states
The thermal energy.
liquid states have enough thermal energy to overcome IMF and can move around each other
Solid states have atoms/molecules locked in place and can only vibrate back and forth in their fixed positions
At room temperature and pressure, medium to strong IMF’s result in:
liquid or solid states with a high boiling/melting point
At room temperature and pressure, weak IMF’s result in:
gas states with low melting/boiling points
IMFS can result from
full charges, dipoles, and/or temporary charges
The energy of a compound becomes _______ as oppositely chatged species _______ in magnitude or ______ in distance
more exothermic, increase, come closer
Difference between intermolecular and intramolecular forces
‘Intra’ means within, so intramolecular forces occur within a molecule. ‘Inter’ means between, so intermolecular forces occur between molecules
What are the main types of IMF in order of strongest to weakest
Ion dipole, Hydrogen bonding, Dipole-Dipole, London Disperson forces
What are London dispersion force characteristics?
present in all molecules
-result from fluctuations in e- distributions, resulting in an instantaneous dipole
What do instantaneous dipoles do to neighboring molecules
They create temporary dipoles in them
What is polarizability and how does it relate to LDF’s
Polarizability is how easily an electron can move, the magnitude of LDF’s depends on the atoms/molecules
What are some characteristics related to the polarizability
Larger molecules/atoms are more polarizable due to their larger electron cloud
a larger electron cloud allows for a stronger LDF since the electron is held less tightly by the nucleus
How is molar mass and surface area related to LDF’s?
Larger molar masses create a higher LDF since the electrons are dispersed over a greater area
Shape dictates the overall surface area where LDF can occur
How can you predict higher LDFs (and therefore higher boiling points)
first, compare the molar masses
if the molar masses are similar then consider the shape
What are some characteristics of Dipole-Dipole Forces?
-they are present in all polar molecules (molecules that have regions of partial negative and partial positives, creating permanent dipoles)
-compounds with LDF and dip-dip have higher melting/boiling points than compounds with just LDF’s
What is true about dipole moments and molar masses?
if the molar masses are similar, then the compound with the greater dipole moment will have a higher boiling point
What is hydrogen bonding?
a special kind of dip-dip force
-only occur in polar molecules that contain H-F, H-O, and H-N bonds
-only occur between a H bonded to F,O,N and the F,O,N on the neighboring molecule
Why do hydrogen bonds occur with F,O,N
F,O, N are small and highly electronegative. these small sizes allow for closer interactions
What is Ion-Dipole Forces
occur when a soluble ionic compound is mixed with a polar compound
How is the rate of vaporization related to temperature, surface area, and IMF
Higher temps, higher surface area=higher rate of vaporization
weaker IMF=higher rate of vaporization
What is vapor pressure
The pressure of a gas in dynamic equilibrium with its liquid
Weak intermolecular forces result in highly volatile substances with high vapor pressures
Strong intermolecular substances result in non volatile substances with low vapor pre
what is sublimation
when a solid becomes a gas without becoming a liquid first
what is deposition
when a gas becomes a solid without becoming a liquid first
what is fusion
it is the transition of a solid to a liquid (melting) it is an endothermic process since solid is higher energy
as intermolecular forces increase what happens to boiling point
it increases
how are surface tension and intermolecular forces related
as surface tension increases, the IMF increases
how is viscosity (thickness of solution) related to IMF
As the IMFs increase the viscosity increases since the molecules are more attracted to eachother and do not move around eachother as much
increases in pressure favor what states of matter?
Denser states
what is surface tension
the tendency of liquid to minimize surface area by creating a skin
surface tension decreases with decreasing intermolecular forces
what is viscosity
the resistance of liquid to flow
what are adhesive forces and what is their relationship to cohesive forces
the attraction between liquid molecules and tube surfaces
if the adhesive forces are stronger than the cohesive forces then the liquid will climb up the tube surface until gravity forces a balance with the adhesive forces
what are cohesive forces
the attraction between liquid molecules
what is vaporization
the transition of a liquid to a gas when enough energy has been put into a liquid to overcome the IMF’s
how is vaporization related to temperature, surface area, and intermolecular forces
the rate of vaporization increases with increased temperature and surface area and with weak IMFS
what is the heat of vaporization?
the amount of heat required to vaporize 1 mol of liquid into a gas
