Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Organic Chem AS Mock > TOPIC 2: Shapes of Molecules & Intermolecular Forces > Flashcards

TOPIC 2: Shapes of Molecules & Intermolecular Forces Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Chemistry flashcards Periodic Table flashcards Chemistry 101 flashcards Organic Chemistry 101 flashcards
1
Q

2 areas of electron density

A

Linear : 180°

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

2 areas of electron density w/ 2 lone pairs

A

Non-linear : 104.5°

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

3 regions of electron density

A

Trigonal planar : 120°

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

3 regions of electron density w/ 1 lone pair

A

Pyramidal : 107°

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

4 areas of electron density

A

Tetrahedral - 109.5°

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

5 areas of electron density

A

Trigonal bipyramidal - 90° & 120°

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

6 areas of electron density

A

Octahedral - 90°

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Wedges: solid line

A

In the paper

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Wedges: solid wedge

A

Coming out of paper

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Wedges: dotted wedge

A

Going into paper

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Electron pair with strongest repulsion

A

Lone pair - lone pair

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Electron pair with weakest repulsion

A

Bonding pair - bonding pair

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does a lone pair affect the bond angle

A

Reduces it by 2.5° for each lone pair

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Explain the trend of in the melting points of the halogens as you move down group 7 (3)

A
  • melting points increase down group 7
  • greater number of electrons
  • so induced dipole-dipole interactions are stronger
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Explain why each bond angle in BH3 is 120° (2)

A
  • boron has 3 bonding pairs of electrons
  • which repel each other equally
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Explain how the C-H bond differs from the N-H bond in terms of bond polarity (2)

A
  • N-H bond more polar than C-H
  • as difference in electro negativity between nitrogen and hydrogen atom is larger
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Define: electronegativity (2)

A
  • the ability of an atom to attract electrons
  • in a covalent bond
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

State whether HCONH2 is a polar molecule (3)

A
  • polar
  • because polar bonds present
  • unsymmetrical distribution of charge
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the meaning of δ+ (1)

A

Partial positive charge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

State which property of atoms causes a bond to be polar (1)

A

Electronegativity difference

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Which compound isn’t influenced by a lone pair of electrons?

A

BF3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What compound has a shape that is influenced by lone pairs around the central atom?

A

ClF3

23
Q

State how two carbon atoms form a carbon-carbon bond in graphene (1)

A

Shared pair of electrons

24
Q

Empirical formula of graphene

A

CH

25
Q

Explain why a CH2Cl2 molecule is polar (1)

A

The molecule is non-symmetrical

26
Q

Predict and explain shape of the AlH4- ion (3)

A

Shape : tetrahedral

Explanation :
- equal repulsion
- b/w 4 bonding pairs

27
Q

Why does electronegativity increase as you go up the group?

A

Because there’s less shells so less shielding -> electrons are attracted more easily

28
Q

How do lone pairs affect polarity

A

Lone pair:
- non-symmetrical
- polar

No lone pair:
- symmetrical
- non-polar (dipoles cancel out)

29
Q

What molecules are never polar

A

Hydrocarbons

30
Q

Estimate the H-O-H bond angle in water using electron pair repulsion theory (3)

A
  • 104.5°
  • 4 areas of electron density
  • extra repulsion due to lone pairs
31
Q

Suggest a way that the bond angle in NH3 could become 109.5° (3)

A
  • Nitrogen can form a dative bond
  • therefore no longer any lone pairs
  • so no extra repulsion
32
Q

Minimum and maximum number of electrons in outer shell of sulfur (2)

A

Min = 8

Max = 18

33
Q

Predict if the SF6 molecule is polar and explain why. (2)

A
  • non polar
  • no overall dipole
34
Q

Explain why the C-F bond does not readily break (2)

A
  • C-F bond is stronger
  • and more polar
35
Q

Predict and explain if halogens can conduct electricity in any state (2)

A
  • do not conduct in any state
  • as there’s no delocalised electrons
36
Q

Order the three main types of intermolecular forces in ascending order of strength (3)

A
  • induced dipole-dipole
  • permanent dipole-dipole
  • hydrogen bonding
37
Q

Identify the strongest intermolecular force between:

i) methanal molecules
ii) methanoic acid molecules
iii) water and methanal
iv) water and methanoic acid

A

i) permanent dipole-dipole forces

ii) hydrogen bonding

iii) hydrogen bonding

iv) hydrogen bonding

38
Q

Explain why sodium methanoate is solid at room temp and methanoic acid is a liquid (3)

A
  • sodium methanoate is ionic
  • methanoic acid is a simple covalent substance
  • ionic bonds are stronger
39
Q

Explain why the boiling point of H2O does not follow the Group 6 boiling point trend (2)

A
  • water is able to form hydrogen bonds between molecules
  • hydrogen bonds are the strongest intermolecular forces
40
Q

Explain how physical properties of ammonia allow it to be easily separated in the Haber process (2)

A
  • boiling point of ammonia higher than that of hydrogen and nitrogen
  • mixture of gases can be cooled so ammonia condenses first
41
Q

Explain why intermolecular forces between water molecules are stronger than those b/w ammonia molecules (4)

A
  • oxygen has a greater mass
  • so stronger dipole-dipole interactions
  • water can form more hydrogen bonds per molecule than ammonia
  • as there’s 2 lone pairs of electrons on oxygen but only 1 on nitrogen
42
Q

Explain why the bond angle in NH3 is different to that of BH3 (2)

A
  • lone pairs of electrons on N have greater repulsion
  • so pairs of electrons arrange themselves as far apart as possible to minimise repulsion
43
Q

Explain why CCl4 is non-polar but CH3Cl is polar (3)

A
  • C-Cl bond is polar
  • CCl4 is a symmetrical molecule
  • polarity of C-Cl bonds cancel out in CCl4
44
Q

Explain whether B-Cl bond or B-H bond is more polar (4)

A
  • B-Cl = covalent bond
  • formed by shared pair of electrons between B and Cl atom
  • B-H bond less polar than B-Cl bond
  • as difference in electronegativity in B-H is smaller
45
Q

Predict whether the b.p of CH4 is lower than the b.p of CCl4 (4)

A
  • lower than CCl4
  • bcs CCl4 has more electrons
  • therefore stronger London forces in CCl4
  • so more energy required to break intermolecular forces b/w CCl4 molecule
46
Q

Predict whether each is polar or non polar: (3)

OF2
PF3
BCl3

A
  • OF2 = polar
    ➡️ bond polarities DON’T cancel out
  • PF3 = polar
    ➡️ bond polarities DON’T cancel out
  • BCl3 = non-polar
    ➡️ bond polarities DO cancel out
47
Q

Explain why ice has a density lower than liquid water (2)

A
  • water molecules in ice spread further away
  • hydrogen bonding between water molecules causes ice to have this anomalous density
48
Q

Explain why the m.p of water is higher than that of phosphine (3)

A
  • water has hydrogen bonds
  • phosphine has permanent dipole-dipole forces
  • hydrogen bonds require more energy to overcome
49
Q

Compare the bond angles in F-C-F and F-N-F. (5)

A

F-C-F:
- 120°
- due to 3 areas of electron density around carbon

F-N-F:
- 107°
- due to 4 areas of electron density around nitrogen
- extra repulsion from unbonded pairs

50
Q

Explain difference in molecular polarity in tetraflourohydrazine and tetrafluoroethene (4)

A
  • C-F and N-F bonds are both polar
  • but C2F4 is a symmetrical molecule
  • so bond polarity in C2F4 cancels out
  • N2F4 is an unsymmetrical molecule
51
Q

Explain why methanol is soluble in water (3)

A
  • O-H bond = polar
  • methanol can form H-bonds with water
  • H-bonding with water increases solubility
52
Q

Predict whether alkanes are soluble in either water or propanone (5)

A
  • insoluble in water
  • soluble in propanone
  • non-polar molecules
  • dont form h-bonds with water
  • form more London forces w/ propanone
53
Q

Explain why iodine vaporises easily (2)

A
  • weak induced d.p - d.p interactions between molecules
  • these weak forces are easily overcome
54
Q

Explain the difference in electrical conductivity of sodium chloride and iodine (3)

A
  • iodine has no free electrons to carry charge
  • molten NaCl has ions which are free to move
  • solid NaCl has no free ions as they’re fixed in position therefore NaCl cannot conduct when solid

Organic Chem AS Mock (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions