21 IMFA

Question 1

kinetic molecular theory of matter

Answer 1

1. matter is made of tiny particles that are constantly moving
2. all particles have energy (solids have the least while gases have the most)
3. phase change occurs as energy of particles is ↑/↓
4. particles have spaces between them (gas has most while solid has least)
5. atoms + mols have attraction between them; the larger the space, the weaker the force of attraction

Question 2

intra

Answer 2

within

Question 3

holds two mols within the molecule

Answer 3

intramolecular

Question 4

inter

Answer 4

between

Question 5

generally, ___molecular forces are much weaker than ___molecular forces

Answer 5

inter, intra

Question 6

holds two separate molecules

Answer 6

intermolecular

Question 7

also known as “van der Waals forces”

Answer 7

intermolecular forces of attraction

Question 8

who were van der Waals forces named after?

Answer 8

Johannes Diderik van der Waals

Question 9

who proposed london dispersion forces?

Answer 9

american physicist fritz london (1900-1954)

Question 10

4 nonpolar substances

Answer 10

1. hydrogen
2. oxygen
3. nitrogen
4. helium

Question 11

nonpolar substances exist as what state of matter under ordinary conditions?

Answer 11

gas

Question 12

interaction between mols of nonpolar substances is very ____

Answer 12

weak

Question 13

another name for london dispersion forces?

Answer 13

instantaneous dipole-induced dipole interaction

Question 14

what type of compounds ALWAYS exhibit london dispersion forces?

Answer 14

covalent compounds

Question 15

weakest IMFA

Answer 15

london dispersion forces/instantaneous dipole-induced dipole interaction

Question 16

two electrically charged poles

Answer 16

dipole

Question 17

attractive forces between polar covalent molecules w/ permanent dipole

Answer 17

dipole-dipole interaction

Question 18

what makes bond strength decrease?

Answer 18

an increase in distance

Question 19

when are dipole-dipole forces are weak?

Answer 19

if they are in gases, especially with low pressure

Question 20

bond where H is bonded to O, N, F/to O, N, F in another molecule

Answer 20

hydrogen bonding

Question 21

strongest of three types of IMFA

Answer 21

hydrogen bonding

Question 22

examples of hydrogen bonding

Answer 22

ice floating on water, double helix of DNA, folding of protein chains in hemoglobin

Question 23

electrostatic attraction between ion and neutral mol w/ permanent dipole

Answer 23

ion-dipole bonding

Question 24

commonly in solutions of ionic compounds + polar liquids

Answer 24

ion-dipole bonding

Question 25

tendency of material to change into gaseous/vapor state that increases with temp

Answer 25

vapor pressure

Question 26

if IMFA ↑, what happens to vapor pressure?

Answer 26

vapor pressure ↓

Question 27

if IMFA ↑, what happens to boiling pt?

Answer 27

boiling pt ↑

Question 28

temp where vapor pressure = atmospheric pressure

Answer 28

boiling pt

Question 29

temp where vapor pressure at surface = pressure exerted by surroundings

Answer 29

melting pt

Question 30

if IMFA ↑, what happens to melting pt?

Answer 30

melting pt ↑

Question 31

resistance of liquid to flow, dependent on structure of mol as well as temp

Answer 31

viscosity

Question 32

if IMFA ↑, what happens to viscosity?

Answer 32

viscosity ↑

Question 33

attractive force in liquids that pulls surface mols -> rest of liquid, minimizing surface area

Answer 33

surface tension

Question 34

if IMFA ↑, what happens to surface tension?

Answer 34

surface tension ↑

Question 35

what does IMFA determine in a substance?

Answer 35

1. phys properties 2. affects melting + boiling pt, solubility 3. exist in certain states of matter

Question 36

if all other variables are constant, what happens to LDF and molar mass?

Answer 36

london dispersion forces ↑, molar mass ↑

Question 37

substances with ___ have much higher boiling + melting pts, viscosity, surface tension

Answer 37

h-bonds