Unit 3

elastic deformation

temporary change, returns to normal

plastic deformation

permanent change, but doesn’t break

ionic solid

strong inter and intramolecular forces

high melting/boiling point

brittle

not conductive unless dissolved in water

molecular solid

formed by distinct molecules bonded together

strong intramolecular forces, weak intermolecular forces

low melting/boiling point

cannot conduct electricity

covalent network solid

formed by atoms bonded covalently in a 3d network

indicated by presence of B/Si/Ge + element, C + metalloid, or just C

high melting point

does not conduct electricity

metallic solid

sea of electrons keeps metal atoms together

malleable/ductile

good conductors of electricity

dipole-dipole interactions

between polar + polar, increased polarity strengthens

dipole-induced dipole

polar + nonpolar, temporary, electronegative atom of polar molecule repels electrons, creating partial positive charge

London Dispersion Forces

nonpolar + nonpolar, present in all IMFs, stronger with larger molecules b/c more polarizable

hydrogen bonding

H surrounded by F/O/N, type of dipole-dipole, strong

ion-dipole

negative from dipole connects with positive ion + vice versa

stronger IMF effect on boiling point, surface tension, heat of vaporization

boiling point- raised

surface tension- raised

heat of vaporization- raised

volatility

ease of evaporating, stronger IMF lowers

viscosity

resistance to flow, stronger IMF increases

vapor pressure

pressure exerted by a gas when it is at equilibrium with its liquid, stronger IMF lowers b/c liquid doesn’t evaporate as much

relative strength of intermolecular forces

h bonding > dipole-dipole > LDF (when molecules are similar sized); LDF more important when molecules are larger

effect of volume on pressure

as volume increases, pressure decreases; inversely proportional

effect of number of particles on pressure

less particles = less pressure

effect of temperature on pressure

higher temp = higher pressure

ideal gas law

(pressure)(volume) = (# moles)(R)(temp in kelvin)

r

0.08206 atm

8.314 kPa

partial pressure

pressure that each gas would exert if it was the only gas present in the container (mole fraction x total pressure)

graph with same temperature but different masses

heavier molecules move slower and have a narrower distribution

graph with same gas at different temperatures

higher temp = higher velocity = wider distribution

what makes a gas more ideal

higher temperature, lower pressure, weak IMF’s, smaller molecules (more attraction = less ideal)

positive pressure deviation

caused by non-negligible particle volumes (big particles = hit wall more often)

negative pressure deviation cause

stronger interparticle attractions (if they’re attracted to each other, won’t hit wall as often)

molarity

moles solute / liters solution

things to consider when drawing molecules

relative size, orientation (±), number (read directions)

distillate

the liquid that is collected after vaporizing a mixture and then condensing the vapor back into a liquid during the process of distillation (lowest boiling point)

chromatography

substances with similar polarity as mobile phase (liquid) will move further up, substances with different polarity to liquid won’t move as far

higher solubility

stronger interactions between solute + solvent molecules

lower Rf value

spot is lower on the plate/didn’t move as far

gas relationship between temp and solubility

as temp increases, solubility decreases

solid relationship between temp and solubility

temp increases, solubility increases

microwave radiation

rotates molecules

infrared radiation

vibrates molecules (move closer/further from each other)

ultraviolet/visible light

transitions in energy levels of electrons

ultraviolet wavelength

1-400 nm

visible light wavelength

400-750 nm

infrared wavelength

750 nm- 1 mm

microwave wavelength

1 mm- 1 m