Intermolecular Forces Flashcards
Polarizabaility
The way the change distribution in a molecule can be distored to induce a temporary dipole
Boiling points are based on what?
The strength of the intermolecular forces (The stronger the forces the higher the boiling point)
When the dipole moment increase so does what?
The boiling point
Vapor pressure increase as _____ inceases until its equals the external pressure over the liquid ( Which causes liquids to boil)
Temperature
Why do gases expand?
Since gases are widely separated particles their average energy of attraction between the particles is smaller than average energy of the particles and since there isnt strong attraction between the particles the gas expands
Boiling points of halogens & noble gases increases when ______ increase
Molecular weight
When the polarityof a molecule increase what happens?
Its intermolecular attraction increases as well
Dipole - Dipole forces are effective when what?
Polar molecules are very close to another
Polar molecules are dipoles because they have what?
Partial postive ends & partial negative ends
Hydrogen bonds
Intermolecular attraction between the hydrogen atom in a polar connecting to a nearby electronegative atom in another bond
Kinetic Energy does what?
keeps particles apart & moving ( Also depends on Temp.)
Phase Changes
Substances change phases
Cohesive forces are the ___________ of the molecule
Intermolecular forces
The strength of dispersion forces increases as _______ increases
Atomic or Molecular size
Small polar molecular experience what?
High dipole - dipole attraction
Intermolecular Forces
Are forces that exist between molecules
Which is stronger hydrogen bonds or dispersion forces or Dipole - Dipole foces?
Hydrogen bonds are stronger than disperison forces & dipole - dipole forces
Dipole - Dipole increases as the _______ of the molecule increases
Dipole Moment
Critical Pressure
The pressure required to bring about liquidifcation at the critical temperature
Substances with high vapor pressure evaporate _____ than substances with lower vapor pressure
Quicker
Increasing ____ on a gas forces the molecules closer together, which increases the strength of the intermolecular forces of attractions
Pressure
The heat of sublimation is the sum of what?
The sum of heat of fusion & heat of vaporization
Which intermolecular forces are strongest and which is weakest?
Solid < Liquids < Gases ( Strongest to weakest)
Adhesive forces are forces between the _______ & the ______
Liquid & the tube
When two substances have the same weight & shape then their disperison forces are what?
Equal
Large molecules tend to have __________ because they have more electrons & their electrons are further from the nuclei
Greater polarizability
The physical properties of liquids & solids are due to what?
Intermolecular forces
What electronegative atoms can hydrogen form a hydrogen bond with?
N, O, & F
Disperison forces are found in ________ & _________ when molecular weight increses
In all molecules & increase
Adhesive forces
Intermolecular forces that bind a substance to a surface
Ion - Dipole Force
Exist between an ion & the partial charge on the end of a polar molecule
When a molecule has a high boiling point it means what?
Their intermolecular attractions are stronger
Why do liquids take the shape of a container?
The intermolecular forces are strong enough to hold particles close together but not strong enough to keep them from moving past one another, which allows for liquids to take shapes of a container
Heat of sublimtion
Energy required to cause a solid to transform directly into a gas
Cohesive forces
Intermolecular forces bind similar molecules to one another
The strength of the dispersion forces depends on what?
The polarizability of a molecule
Surface Tension
The energy required to increase the surface area of a liquid
Capillary Action
The rise of liquids up a very narrow tube
The state of a substance depends on the balance between the _____ of the particles & ______ energy of attraction
Kinetic Energy & Interparticle energy of attraction
What do the interparticle attraction do?
Tend to draw the particles together
Heat of fusion
Energy required to melt a substance
As temp. decreases so does ________ of the particles, which allows the attraction between the particles to 1st draw the particles together to form liquids & solids
Kinetic Energy
Viscosity
The resistance of a liquid to flow
Nonpolar, low molecular weight, & weak intermolecular forces have lower _______ & ______ than molecules that are polar & higher molecular weight
Lower Critical temp & pressure
Solids & Liquids are ______ because the particles in a solid & liquid are fairly close together when compared to gases
Condensed Phases
Dynamic Equilibrium
Occurs when evaporation of a liquid & condensation occur at equal rates
Dipole - Dipole Forces
Are weaker than ion - Dipole Attraction and cause when neutral polar molecules attract rach other when the positve end of one molecule is near the negative end of another
What are the 3 types of intermolecular forces that are usually called van der waals forces?
- Dipole -Dipole Attractions
- London Dispersion Forces
- Hydrogen Bonds
London dispersion forces
When the temporary dipole in one atom can induce a similar temporary dipole on an adjacent atom causing the atoms to become attracted to one another
Critical Temperature
The highest temp. at which a liquid phase can be formed
Dipole -dipole add to disperison forces & depend on what?
Polarity
Viscosity increases as what increase?
AS molecular weight increase ( The greater the visvcosity the slower the liquid moves)
When two molecules differ in size which one will have the strongest attractions?
The larger one
Viscosity descreases as what increases?
Temperature
Heat of vaporization
Energy required to make a substance vaporize
Volatile
Liquids that evaporate readliy
Normal Boiling point
When a liquid boils at 1 atm
Covalent Network Solids
Consist of atoms held together through covalent bonds & are very hard & have high melting points
(Ex. Dimonds & graphite)
Ionic Solids
Between metal & nonmetal, consist of atoms held together by electrostatic Attraction & ionic bonds where the strength depends the charge of the atoms)
They are also brittle & have high melting points
Metallic Solids
Held together by metallic bonds & usually with metals were a flow of electrons can occur easily. They are also malleable & ductile
Simple cube has how many atoms?
1 atom
Body-Centered has how many atoms?
2 atoms
Face-centered has how many atoms?
4 atoms
