unit 3

Question 1

intermolecular forces

Answer 1

attraction between atoms, ions, or molecules that hold them together (look at atom types to determine IMF)

Question 2

london dispersion forces (LDF)

Answer 2

occurs between all molecules (even nonpolar)
⮕ lowest strength

Question 3

dipole-dipole

Answer 3

between polar molecules
⮕asymmetrical molecules
⮕ more polar (difference in polarity) the stronger the attraction

Question 4

hydrogen bonding

Answer 4

polar molecules
⮕type of dipole-dipole
⮕H attached to FON

Question 5

ionic

Answer 5

occurs between metal and nonmetal atoms
⮕ stronger when charges are larger and the ions are smaller (coulombs law)

Question 6

metallic

Answer 6

occurs between only metals

Question 7

network covalent

Answer 7

between C, Si. C and O or Si and O.
multiple covalent bonds form large macromolecules
⮕stronger when there are more covalent bonds formed.

Question 8

Properties of substances due to IMF’s

Answer 8

boiling, melting, freezing point 🡱
enthalpy of fusion/vaporization 🡱
vapor pressure 🡳
viscosity 🡱
surface tension 🡱
lattice energy 🡱
solubility 🡳

Question 9

lattice

Answer 9

3D system of points; positions of centers of the components

Question 10

ionic solids

Answer 10

ions at points of lattice that describe the structure of the solid
🠮 smaller ions and ions with higher charges will have stronger attractions between ions –> higher lattice energy value
🠮 brittle due to repulsion (1 layer slides across another) causing solid to vibrate
🠮 conduct electricity when ions are mobile (melted or dissolved)
🠮generally occurs between metal cations and nonmetal anions

Question 11

network covalent solids

Answer 11

atoms at lattice points with strong covalent bonds (Boron, Carbon, Silicone)
🠮only formed from nonmetals
🠮characterized by hardness, strength, and high melting points

Question 12

molecular solids

Answer 12

composed of distinct, individual units of covalently- bonded molecules attracted due to weak intermolecular forces
🠮nonmetal atoms covalently bonded together
🠮have low melting points
don’t conduct electricity bc valence electrons tightly held within covalent bonds and lone pairs of each constituent molecule
🠮 sometimes polymers (large molecules)

Question 13

metallic solids

Answer 13

consist of metallic crystals with spherical metal atoms packed together and bonded to each other equally in all directions
🠮movement of electrons cause metals to be good conductors of heat and electricity.

Question 14

polarization

Answer 14

ability of an atom to form a temporary dipole
–> LDS stronger when atom or molecule has more electrons

Question 15

the more polar the molecule

Answer 15

the stronger the attraction

Question 16

the more polatizable

Answer 16

the stronger the LDF