Intermolecular Forces Flashcards
What types of molecules have electrons that ARE shared equally/the electrons are NOT moved in one particular direction (ex: CF4)
Non-polar molecules
ALL hydrocarbons are what (ex: C3H3)?
Non-polar
What types of molecules have electrons that are NOT shared equally/the electrons ARE moved in one specific direction (ex: CHF3)?
Polar molecules
What do polar molecules tend to be?
Dipole
What are forces between molecules that can determine the property of a substance called?
Intermolecular forces (IMF)
Which type of IMF is being described?:
- Everything has _______
- is the WEAKEST type of IMF
- single atoms only have _______
- ex: Kr (Krypton)
London Dispersion
Which type of IMF is being described?:
- occurs between POLAR molecules
- creates PERMANENT ______ (they will always stick together after initial attraction)
- has stronger IMF than London dispersion
- ex: 2 HBr molecules
Dipole-Dipole
Which type of IMF is being described?:
- not really a traditional bond
- occurs between specific atoms (O-H, F-H, N-H)
- partial charges are more EXTREME than dipole-dipole
- stronger IMF than dipole-dipole
- ex: 2 H2O atoms
Hydrogen “bonding”
Which type of IMF is being described?:
- half IONIC and half DIPOLE
- charges are FULL, not partial
- STRONGEST IMF
- ex: Na+ in H20
Ion-Dipole
For IMF, larger charges equal what?
Stronger attraction
For IMF, longer distance equals what?
Weaker attraction
What is the energy needed to INCREASE the surface area (or break the “skin”) (ex: water bubbling over a cup)?
Surface tension
What is the relationship between IMF and surface tension (effect of IMF)?
Higher IMF= Higher surface tension (b/c of intense attraction)
What is the resistance of a liquid to flow (thick substance)?
Viscosity
What is the relationship between IMF and viscosity (effect of IMF)?
Higher IMF= Higher viscosity (b/c they want to stick together)
What is the ability of a liquid to move up a thin line AGAINST gravity?
Capillary action
What are the attractions (IMF) WITHIN A substance (ex: mercury in a test tube)?
Cohesive forces
Do cohesive forces have weak or strong adhesive forces?
Weak adhesive forces
What are the attractions (IMF) BETWEEN TWO substances (ex: water in a test tube)?
Adhesive forces
What are the determinants of IMF strength?
Molar mass and surface area
What is the relationship between molar mass and boiling point?
Higher molar mass=Higher boiling point
What is special about the aspect of surface area in IMF strength?
If the molar masses are equal, the one with a HIGHER surface area has HIGHER IMF
What is the transition from a liquid to a gas (phase change) (ex: when a rain puddle disappears after a few days)?
Vaporization
What is the transition from a gas to a liquid (phase change)?
Condensation
What are the effects of vaporization?
1.) Temperature/Energy
2.) IMF
3.) Surface Area
What is the relationship between temperature/energy with vaporization?
Higher vaporization=Higher temperature
What is the relationship between IMF and vaporization?
Higher vaporization=Less strength of IMF (ex: it takes more energy to break apart stronger magnets than weak ones)
What is the relationship between surface area and vaporization?
Higher vaporization=Higher surface area
Is vaporization exothermic or endothermic?
ENDOthermic (+) (is TAKING energy)
What is the first step of comparing molecules vapor pressure, boiling point, and IMF?
You can compare the TYPES/NUMBER of IMF the molecules have (the more IMFs they have, the HIGHER their boiling points are and the LOWER their vaporization and vapor pressure)
What is the second step of comparing molecules vapor pressure, boiling point, and IMF?
You can compare how many H-BONDS they have (the more H-bonds they have, the HIGHER IMF they have, the HIGHER boiling points they have, and the LOWER their vaporization and vapor pressure are)
What is the third step of comparing molecules vapor pressure, boiling point, and IMF?
You can compare the molecules’ molar masses (the HIGHER the molar mass, the HIGHER the boiling point; the HIGHER the boiling point, the LOWER the vapor pressure and vaporization)
What is the relationship between boiling point and vapor pressure?
Higher boiling point=Lower vapor pressure
What is the relationship between boiling point and vaporization?
Higher boiling point=Lower vaporization
What is the temperature at which a liquid’s vapor pressure equals external pressure (atmospheric pressure)?
Boiling
What is the boiling point when surrounding pressure equals 1 atm?
Normal boiling point
What is the relationship between temperature and vapor pressure?
Higher temperature=Higher vapor pressure
