21 IMFA Flashcards
kinetic molecular theory of matter
- matter is made of tiny particles that are constantly moving
- all particles have energy (solids have the least while gases have the most)
- phase change occurs as energy of particles is ↑/↓
- particles have spaces between them (gas has most while solid has least)
- atoms + mols have attraction between them; the larger the space, the weaker the force of attraction
intra
within
holds two mols within the molecule
intramolecular
inter
between
generally, ___molecular forces are much weaker than ___molecular forces
inter, intra
holds two separate molecules
intermolecular
also known as “van der Waals forces”
intermolecular forces of attraction
who were van der Waals forces named after?
Johannes Diderik van der Waals
who proposed london dispersion forces?
american physicist fritz london (1900-1954)
4 nonpolar substances
- hydrogen
- oxygen
- nitrogen
- helium
nonpolar substances exist as what state of matter under ordinary conditions?
gas
interaction between mols of nonpolar substances is very ____
weak
another name for london dispersion forces?
instantaneous dipole-induced dipole interaction
what type of compounds ALWAYS exhibit london dispersion forces?
covalent compounds
weakest IMFA
london dispersion forces/instantaneous dipole-induced dipole interaction
two electrically charged poles
dipole
attractive forces between polar covalent molecules w/ permanent dipole
dipole-dipole interaction
what makes bond strength decrease?
an increase in distance
when are dipole-dipole forces are weak?
if they are in gases, especially with low pressure
bond where H is bonded to O, N, F/to O, N, F in another molecule
hydrogen bonding
strongest of three types of IMFA
hydrogen bonding
examples of hydrogen bonding
ice floating on water, double helix of DNA, folding of protein chains in hemoglobin
electrostatic attraction between ion and neutral mol w/ permanent dipole
ion-dipole bonding
commonly in solutions of ionic compounds + polar liquids
ion-dipole bonding
tendency of material to change into gaseous/vapor state that increases with temp
vapor pressure
if IMFA ↑, what happens to vapor pressure?
vapor pressure ↓
if IMFA ↑, what happens to boiling pt?
boiling pt ↑
temp where vapor pressure = atmospheric pressure
boiling pt
temp where vapor pressure at surface = pressure exerted by surroundings
melting pt
if IMFA ↑, what happens to melting pt?
melting pt ↑
resistance of liquid to flow, dependent on structure of mol as well as temp
viscosity
if IMFA ↑, what happens to viscosity?
viscosity ↑
attractive force in liquids that pulls surface mols -> rest of liquid, minimizing surface area
surface tension
if IMFA ↑, what happens to surface tension?
surface tension ↑
what does IMFA determine in a substance?
- phys properties
- affects melting + boiling pt, solubility
- exist in certain states of matter
if all other variables are constant, what happens to LDF and molar mass?
london dispersion forces ↑, molar mass ↑
substances with ___ have much higher boiling + melting pts, viscosity, surface tension
h-bonds
