Intermolecular forces

Question 1

where do permanent dipole-dipole forces occur

Answer 1

between polar molecules

Question 2

examples of dipole-dipole

Answer 2

hydrogen halides
- HCl
-HBr
-HI

Question 3

how does a dipole-dipole form

Answer 3

shared pair of electrons are more attracted to one molecule
the delta + on one molecule attracts the delta - on an adjacent molecule

Question 4

where do van der Waals exist

Answer 4

between all molecules
the only IMT to exist between non-polar molecules

Question 5

how does a Van der Waal arise

Answer 5

if at any moment there is more electrons on one side of the molecule than the other it creates a temporary dipole
- the temporary dipole causes a dipole on the adjacent molecule called an induced dipole so molecules attract

Question 6

what does the strength of the van der Waal depend on

Answer 6

the size of the molecule
larger molecule = more electrons = bigger Van der Waal force

Question 7

where do hydrogen molecules exist

Answer 7

between molecules which contain F-H , O-H, N-H bond
most electronegative atoms

Question 8

how does hydrogen bonding in water arise

Answer 8

oxygen is more electronegative than hydrogen
o= delta -
H = delta +
attraction between the delta + H in one molecule and lone pair of electrons on the O in the adjacent molecule

Question 9

for hydrogen bonding to occur what must happen

Answer 9

1.hydrogen atom is directly attached to a very electronegative tom
2. it must be a O,N,F atom
3.the electronegative tom must have an unshared pair of electrons
4.the big difference in electronegativity makes the bonds highly polar

Question 10

electronegativity

Answer 10

relative tendency
of an atom in a covalent bond in a molecule to attract electrons in a covalent bond to itself
-measured on the Pauling scale

Question 11

factors affecting electronegativity

Answer 11

it increases across a period = number of protons increases and the atomic radius decreases = electrons in same shell are pulled in more

it decreases down the group = the distance between the nucleus + outer electrons increases + shielding of inner shell electrons increases

Question 12

what will a compound with elements containing different electronegativities be

Answer 12

ionic

Question 13

how does a polar covalent bond form

Answer 13

when elements in the bond have different electronegativities

Question 14

what does a polar covalent bond mean

Answer 14

unequal distribution of electrons in the bond producing a charge separation (dipole)

Question 15

what is a symmetric molecule

Answer 15

all bonds are identical and lone pairs will not be polar even if individual bonds within the molecular are polar
individual dipoles cancel out due to symmetrical shape of molecule
molecule is non polar no net dipole