ch. 11 - liquids and intermolecular forces

ionic

• nonmetal + metal

• held together by the attraction between cations and anions

• “stealing”/transfer of e⁻ from one atom to another

covalent

• nonmetal + nonmetal/metalloid

• sharing of a pair of e⁻

intermolecular forces (IMFs)

• between molecules

• electrostatic in nature (can’t make a true bond)

• weaker forces holding molecules together

• influence physical properties of solids and liquids

four major types of IMFs

1. dispersion

2. dipole-dipole

3. h-bonding

4. ion-dipole

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dispersion

dispersion

• consider electrically neutral, non-polar atoms/molecules

• movement of e⁻ around the atom creates an instantaneous diople movement

what factors dictate strength?

polarizability & molecular shape

polarizability

• how easy it is to distort the charge distribution?

• how “squishy” is the electron cloud?

molecular shape

* when the amount of contact increase between molecules the strength of interaction increases

dipole-dipole

dipole-dipole

* between polar molecules with a permanent dipole movement

h-bonding

h-bonding

• not an actual bond

• strongest IMF

• FON

ion-dipole

ion-dipole

• in between an ion and polar molecule molecule

• cations attracted to neg end of dipole

• anions attracted to pos end of dipole

surface tension

• the energy required to increase the surface area of a liquid by 1 m^2

• how hard is it to disrupt/pull apart the molecules?

viscosity

* the resistance of liquid to flow

vapor pressure

* molecules can escape from the surface of a liquid into the gas phase by evaporation

phase diagrams

* represents condition where equilibrium exist between the different states of matter

critical temp

* highest temp at which a distinct liquid can form

critical pressure

* pressure required to bring about liquification at critical temp

superficial fluid

* beyond the critical point where liquid and gas are indistinguishable (has properties of both liq and gas)

melting point

* point on the line separating solid and liq at 1 atm

triple point (+)

* where all 3 phases are in equilibrium

liquid → gas

* vaporization (endo)

liquid ← gas

* condensation (exo)

liquid → solid

* freezing (exo)

liquid ← solid

* melting (endo)

gas → solid

* deposition (exo)

gas ← solid

* sublimation (endo)

heat of fusion (△H_fus)

* solid to liquid

heat of vaporization (△H_vap)

* liquid to gas

heat of sublimation (△H_sub)

* solid to gas

heating curves

• represent phase changes

• temp of system vs heat (energy) added

• indicate the changes that occur when a substance is heated

specific heat

* the amount of heat required to raise the temp of a substance (slope)