imf

Question 1

intermolecular forces (IMF)

Answer 1

an intermolecular force occurs between molecules. it is the force that must be overcome to have a phase change.

Question 2

intermolecular forces occur between four types of substances

Answer 2

molecular substances (2 or more nonmetals)
ionic substances (one metal and one non metal) 
metallic substances (metals) 
network solids (diamonds)

Question 3

molecular substances

Answer 3

three types of intermolecular forces:
dipole-dipole
hydrogen bond imf
London dispersion

Question 4

dipole-dipole

Answer 4

occurs between polar molecules (polar bonds, no symmetry)
the + end of one molecule is attracted to the - end of another molecule
examples: HBr, PH3, H2S

Question 5

hydrogen bond IMF

Answer 5

special type of dipole-dipole force (stronger because of the greater polarity of the molecules)
occurs between molecules that have H bonded to N, O, or F - (highest electronegativities)
examples: H2O, HF, NH3

Question 6

van der waals, temporary dipole-dipole, or london dispersion IMF

Answer 6

occurs between non polar molecules (non polar bonds or polar bonds with symmetry)
occurs as a result of movement of electrons and one molecule becomes temporarily polar and in turn induces another molecule to become polar
example: CO2

Question 7

ionic substances

Answer 7

ionic IMF
occurs between metal and nonmetal
composed of ions in a crystalline structure, + ions attracted to - ions to form a unit cell
examples: NaCl, CaI2, KNO3

Question 8

metallic substances

Answer 8

metallic IMF
occurs between metals or alloys 
"sea of electron" theory 
explains the properties of metals 
conducts electricity 
tends to lose electrons
malleable, ductile

Question 9

network solids

Answer 9

network solid or covalent network IMF
each molecule is bonded in a 3 dimensional network of covalent bonds
only examples: C (in diamond form), SiC, SiO2

Question 10

the strength of the intermolecular force

Answer 10

is directly related to melting point and boiling point

the stronger the IMF the higher the m.p. or b.p.

Question 11

strength of IMF

Answer 11

london dispersion - dipole-dipole - H bond - ionic - metallic - network solid