chem topic 5

Question 1

what is intermolecular forces

Answer 1

attractive forces between molecules

Question 2

what is the state of a substance

Answer 2

balance between IMF (hold particles together) and kinetic energy (moves particles apart)

Question 3

what is boiling point

Answer 3

-liquid to gas phase transition
-requires the IMF to break
-high boiling point=strong IMF

Question 4

4 types of IMF

Answer 4

london dispersion
dipole-dipole
hydrogen bonding
ion dipole

Question 5

are IMF weaker than covalent bonds?

Answer 5

yes (smaller charges over long distance)

Question 6

london dispersion

Answer 6

-present in all molecules
-distribution of electrons is symmetric
-attraction between dipole and induce dipole

Question 7

two factors that affect the strength of london dispersion forces

Answer 7

polarizability (ability to move around, increases down table)
molecular shape

Question 8

molecules with greater surface area in LDF will have

Answer 8

stronger forces

Question 9

dipole dipole force

Answer 9

-molecules with dipole are attracted to each other
-pos attracted to neg end
increase boiling point
-larger dipole, stronger DDF

Question 10

hydrogen bonds

Answer 10

-when H is bonded to N,O,F the dipole is unusually strong

Question 11

are hydro bonds stronger than DDf?

Answer 11

yes

Question 12

whats a doner and acceptor?

Answer 12

-hydro bonding
-H doner
-N,O,F acceptor

Question 13

ion dipole forces

Answer 13

-ion and polar molecule
-strength of interactiono

Question 14

order of IMF strength from large to small

Answer 14

ion dipole-hbond-DDF-LDF

Question 15

what happens if one molecule is much larger than the other? what happens if similar

Answer 15

L: LDF will dominate
S: strongest IMF will dominate

Question 16

IMF chart to determine what force

Answer 16

draw out (11.3)

Question 17

properties of liquids

Answer 17

-surface tension
-viscosity
-capillary
-boiling point

Question 18

surface tension

Answer 18

amount of energy needed to increase the SA of a liquid by unit amount
-SA less stable due to feweer interactions
-minmize SA to min enerery
-inc in IMF will inc Surf tension

Question 19

viscosity

Answer 19

resistance of a liquid to flow
-increases with stron IMF and decrease with higher temp

Question 20

capillary action

Answer 20

ability of a liquid to flow in narrow spaces in opposition to external forces like gravity
-water flows up from adhesive forces to surface are greater then cohesive between molecules in liquid

Question 21

phase transition

Answer 21

substance changes from one phase to another
-accompanied by energy (energy independant on journey)

Question 22

pressure

Answer 22

amount of force applied to an area

Question 23

how to messure difference of pressure and gas

Answer 23

manometer

Question 24

what happens to molecules at surface of liquid

Answer 24

can obtain enough kinetic energy to break free of IMF (vapouriztion)

Question 25

vapour pressure

Answer 25

gas over liquid equalibrium -increases with temp -temp where VP and AP are = is boiling point

Question 26

look at slides 11.6

Answer 26

slides and examples

Question 27

sublimation, whats the opposite

Answer 27

going from solid to gas without liquid state (ice cubes shrinking) -deposition (gas to solid)

Question 28

proper name for melting and its reverse process

Answer 28

fusion -freezing

Question 29

why does it take less heat to melt ice than it does to vaporize liquid water?

Answer 29

you need to break IMF for a molecule to enter a gas phase

Question 30

phase diagrams

Answer 30

shows pressures and temperatures including equilibrium phases

Question 31

supercritical fluid

Answer 31

gas and liquid properties at the same time -critical point on graph

Question 32

triple point

Answer 32

where S,L,G are at equalibrium

Question 33

condensed phases

Answer 33

liquids and solids

Question 34

solids can either be (two types)

Answer 34

amorphous: lack structure, look like non flowing structures crystalline solids: have regular repeating patterns

Question 35

types of Cys solids

Answer 35

-ionic, metallic, covalent, molecular

Question 36

ionic crys

Answer 36

-higher melt, brittle -uses empirical formula (reduce) -electrostatic attractions holds solid together

Question 37

metallic

Answer 37

-metals -valence e move freely

Question 38

covalent

Answer 38

-electrons being shared -strong, hard -high melting -can conduct

Question 39

molecular

Answer 39

-held together by IMF, solid -not conductive -low melt

Question 40

unit cell composes of

Answer 40

lattice (outer area) motif (molecules)

Question 41

coordination number and each number for the cubics

Answer 41

number of balls around center atom (6,8,12)

Question 42

how many lattice points does simple cubic have? give formula

Answer 42

8- the corners 1/8=1 atom

Question 43

what three types of cubic are there

Answer 43

simple, body centered, face centered

Question 44

how many lattice points does body cubic have? give formula

Answer 44

-with center 1 whole

Question 45

how many lattice points does face cubic have? give formula

Answer 45

-with faces 1/2

Question 46

whats the formula for a edge

Answer 46

1/4

Question 47

what do we use to determine space between atoms in crys lattice?

Answer 47

diffraction period (con and des waves)

Question 48

band theory (easier to move through w no gaps)

Answer 48

-MOT dealing with solids -valence (top white, highest energy) -conduction (bottom grey, lowest energy)

Question 49

describe metallic, insulator, semi conductor in band theory

Answer 49

m- no gaps semi- small gap -insulator- large gap

Question 50

why are IMF weaker than covalent bonds?

Answer 50

smaller charges acting over longer distances