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a level chemistry > module 2 section 2 - electrons, bonding and structure > Flashcards

module 2 section 2 - electrons, bonding and structure Flashcards

1
Q

state the properties of ionic compounds (4)

A
  • giant ionic lattice
  • solid at RTP
  • soluble
  • conduct electricity when molten but not when solid
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2
Q

explain why ionic compounds are solid at RTP (3)

A
  • strong attraction between ions
  • lots of energy needed to overcome attraction
  • to break bonds
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3
Q

explain the solubility of ionic compounds (3)

A
  • dissolve in polar solvent
  • cations attracted to oxygen
  • anions attracted to hydrogen
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4
Q

describe and explain the electrical conductivty of ionic compounds (4)

A
  • dont conduct when solid
  • as ions fixed in place in lattice structure
  • conduct when molten
  • ions are mobile
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5
Q

describe what is meant by the term ionic lattice in terms of the type and arracngement of particles present (2)

A
  • repeating pattern
  • of oppositely charged ions
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6
Q

what direction do oppositely charged ions attract ?

A

in all directions

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7
Q

give an example of a hypovalent compound

A

BF3

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8
Q

give an example of a hypervalent molecule

A

SF6

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9
Q

what is hypovelent

A

when one atome is covalently bonded but hasnt got a full outer shell

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10
Q

what is hypervalent

A

when one atom covalently bonded has more than 8 electrons in its outer shell

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11
Q

h

A

j

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12
Q

O-O = +300KJmol-1
O=O = +500KJmol-1

why are these values positive and what does this tell you about the strength of the O=O compared to O-O ? (3)

A
  • positive because energy has to be put in to break bond
  • = endothermic process
  • O=O bond is stronger than O-O
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13
Q

Draw the structure of a linear bond

A
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14
Q

Draw the structure of a trigonal planar bond

A
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15
Q

Draw the structure of a tetrahedral bond

A
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16
Q

Draw the structure of a (trigonal) pyramidal bond

A
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17
Q

Draw the structure of a non linear bond

A
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18
Q

Draw the structure of an octahedral bond

A
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19
Q

State the shape and bond angle of a bond that has 2 electron regions 2 bonding regions and 0 lone pairs (2)

A
  • linear
  • 180
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20
Q

State the shape and bond angle of the bind that has 3 electron regions 3 bonding regions 0 lone pairs (2)

A
  • trigonal planar
  • 120
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21
Q

State the shape and bond angle of a bond that has 4 electron regions 4 bonding regions and 0 lone pairs

A
  • tetrahedral
  • 109.5
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22
Q

State the shape and bond angle of a bond that has 4 electron regions 3 bonding regions and 1 lone pair (2)

A
  • pyramidal
  • 107
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23
Q

State the shape and bond angle of a bond that has 4 electron regions, 2 bonding regions and 2 lone pairs (2)

A
  • non linear
  • 104.5
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24
Q

State the shape and bond angle of a bond that has 6 electron regions 6 bonding regions and 0 lone pairs (2)

A
  • octahedral
  • 90
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25
What is meant by a bond? (1)
A region of electron density
26
How do lone pairs of electrons compare to bonded pairs? (1)
A region of much greater electron density
27
What makes a molecules more stable (3)
* Greater bond angle * less repulsion * more stable
28
Ammonia and boron trifluoride both have 3 bonding regions. Why is ammonia not also a tribunal planar?
Ammonia has a lone pair of electrons
29
Ammonia and methane both have 4 electron regions why is ammonia not also tetrahedral
Lone pairs repel more than bonded pairs
30
Why is water not linear? (2)
Bonded pair - bonded pair Lowest energy arrangement
31
Explain the difference on how bonded and lone pairs repel
• Bonded pairs repel eachother equally - lone pairs repel more than bonded pairs - Each lone pair reduces the bond angle between bonded pairs by 2.5°
32
Explain the bond angle in sulfur hexafluoride (3)
• 90° bond angle . 6 bonding regions and no lone pairs • bonded pairs repel eachother equally
33
Explain the bond angle in phosphorous trichloride (3)
- 107° bond angle • 3 bonding regions and I I one pair - lone pairs repel more than bonded pairs
34
Explain the bond angle in water (3)
• 104.5 bond angle • 2 bonding regions and 2 lone pairs . Lone pairs repel more than bonded pairs
35
Explain the bond angle in a sulfate lon(3)
- 109.5° bond angle • 4 bonding regions • bonded pairs repel eachother equally
36
Predict the shape of this ion (5)
• 4 electron regions • 3 bonding regions - 1 lone pair • 107° band angle •Pyramidal
37
How do lone pairs of electrons compare to bonded pairs (1)
- a region of much greater electron density
38
Predict the shape of this ion (5)
• 3 electron regions • 3 bonding regions • o lone pairs • 120° band angle • trigon al planar
39
Predict the shape of this molecule (5)
- 7 electron regions - 3 bonding regions - 2 lone pairs - 104.5° bond angle - non linear
40
Predict the shape of this molecule (5)
- 2 electron regions - 2 bonding regions - o lone pairs - 180° bond angle -Linear
41
The shape around the oxygen atom in butan-2 -ol is non-linear, predict the c-o-h bond angle and explain this shape (4)
• 104.5° band angle • it has 2 banded pairs and 2 lone pairs • lone pairs repel more than bonded pairs
42
Explain now a covalent bond can be polar (3)
• when 2 atoms in a covalent bond have different Electronegativities • electron distribution is asymmetrical • giving atoms partial charges
43
Which direction does a dipole moment point
+ to -
44
What does magnitude of a dipole moment show
How polar the bond is
45
How do polar bonds occur (3)
• Asymmetry in a bond - 1 atom more electronegative • electron cloud distribution =unsymmetrical
46
1s NH3 a polar molecule (2)
47
Explain why CCI4 has polar bonds (1)
Cl atom is more electronegative than C atom
48
Explain why Cecil is not a polar molecule (2)
• Does not have an overall dipole • dipoles act in opposite directions so cancel out (symmetry)
49
Show wether or not SF6 is polar (3)
• Octahedral + symmetrical • au dipoles act in = and opposite directions • non polar molecule with polar bonds
50
Show if H2O is polar or not (3)
• non linear + asymmetric • dipoles both point up-same direction Polar molecule
51
Show if PCI3 is a polar molecule or not (3)
• Pyramidal and asymmetrical • dipoles all point is same direction O polar molecule
52
Show If NH4+ is polar or not (3)
-Tetrahedral and symmetrical - point in opposite directions S cancel out - non polar molecule with polar bonds
53
Show if CO3 2- is polar ion or not (3)
• Dipoles point in opposit directions so cancel out • tribunal planar and symmetric • non polar with polar bonds
54
Show is CH2O is a polar molecule or not
Trigonal planar and asymmetrical Dipoles all face up = same direction Polar molecule
55
Show if BCl2F is a polar molecule or not (3)
• Trig planar and asymmetrical . B-f dipole is more electronegative than B-CI dipole • overall dipoles act in 1 direction as B-CI don't cancel out b-f dipole
56
Explain if NCl3 is a polar molecule or not (3)
• Asymmetrical and pyramidal point in same direction • polar
57
Explain why iodine has a higher melting point than fluorine (2)
• More electrons • stronger London forces between molecules
58
explain how induced dipole dipole interactions arise (3)
- random movement of electrons - induces a dipole in another molecule - attraction between delta + and delta - BETWEEN molecules
59
what factors increase the strength of induced dipole dipole interactions (2)
- increased number of electrons in molecule - increased points of contact / SA
60
explain how an increased number of electrons in a molecule leads to a higher MP and BP (5)
- larger molecule = increased electrons - larger difference in temporary dipole - = stronger IDDI between molecule - = more energy needed to overcome IDDI - = greater MP + BP
61
explain how increased points of contact increase the MP and BP of a molecule (5)
- straight chain molecules - molecules can get closer together - stronger IDI between molecules - more energy needed to overcome - = greater MP + BP
62
describe the properties of molecule which have IDDI forces regarding MP and BP (3)
- stronger IDDI forced BETWEEN molecules - more energy needed to overcome force and separate mlcls - greater MP + BP
63
describe the properties of molecule which have IDDI forces regarding solubility (2)
- like dissolves like - molecules with similar intermolecular forces attract
64
what can induced dipole dipole interactions also be called (2)
- instantaneous dipole induced-dipole forces - London dispersion forces
65
why is the attraction between IDDI so weak (3)
- areas of electro positivity attracts areas of electronegativity - dipole in only temporary - so when there is no diff in electron density there is no attraction
66
why is attraction in PDDI stronger than in IDDI (2)
- dipole is permanent - attraction remains constant
67
explain how permanent dipole dipole interactions arise (3)
- polar mlcls - [permanent dipoles - attraction between delta + and delta - BETWEEN molecules
68
what factors increase the strength of PDDI (3)
- larger diff in electronegativity - increased number of electrons in molecule - increased points of contact / SA
69
explain how difference in electronegativity affects strength of PDDI (3)
- larger diff in electronegativity - = larger diff in dipole - = stronger PDDI between molecules
70
are molecules which contain IDDI as their strongest attraction soluble in water or not. explain your answer (2)
- no (insoluble) - because they are non polar mlcls
71
is c3h6o soluble in water? justify your answer (3)
- soluble - sort chained polar molecule - contains less than carbon atoms
72
is C4H8O soluble in water? justify your answer (3)
- not soluble - long non polar chain - so wont dissolve
73
what is the strongest intermolecular force ?
H-bonds
74
what is the weakest intermolecular force ?
IDD forces
75
state the anomalous properties of hydrogen bonds (2)
- lower density of ice compared to water - relatively high MP + BP
76
explain why ice is less dense that liquid water (3)
- water can form 4 Hbonds w neighboring mlcls - mlcls held further apart by Hbonds - gives ice a tetrahedral structure
77
describe the the MP+BP of molecules containing hydrogen bonds are relatively high (2)
- H bonding = strongest intermlclr force - need for energy to overcome
78
NH3 = -33 degrees BP PH3 = -88 degrees BP ASH3 = -55 degrees BP SbH3 = -17 degrees BP explain the trends in boiling points (4)
- PH3, AsH3 and SbH3 have IDDI only - so BP increases as no. e- in mlcl increases - NH3 has H bonding - H bonding is stronger than IDDI so more energy to overcome
79
why is the solubility of chloroform (CHCl3) 10 times greater than that of carbon tetrachloride (CCl4) in water ? (3)
- C-H bond in chloroform is more polarised due to increased electronegativity of Cl atoms - CHCl3 = polar mlcl but CCl4 = tetrahedral so no overall dipole moment - polar water mlcls interact better w polar CHCl3 mlcls then non polar CCl4 mlcls
80
explain why BP of water is higher than both HF and NH3 (3)
- each H2O mlcl can form 4 H bonds - higher BP than NH3 as H bonds are stronger and has more polar bonds and conatin 2X as many H bonds - higher BP than HF as has 2X as many Hbonds
81
what is the formula for ethanol ?
CH4OH
82
Describe trend shown in graph for H2S, H2Te, and HCl (1)
As size of mock increases Bp increases
83
Compare and contrast boiling points of H2S and HCl (2)
- both have PDDI - but H2S has higher BP as it’s a larger mlcl
84
Boiling points in data shows 2 anomalies, explain why they are anomalous and suggest reasons for these (2)
- HF and H2O are much smaller mocks but have higher BP’s - as they have Hbonds which are stronger intermolecular forces
85
Which molecules can form hydrogen bonds with another molecule of itself (7)
-NH3 -C2H6O -HF -NH2, O2,H2N,OH
86
Which of these molecules can form hydrogen bonds with a water molecule (7)
- all of them
87
Can this molecule form. Hydrogen bind with itself and with a water molecules
- itself: yes -water - yes
88
Can this molecule form a hydrogen bind with itself and with water
Itself: yes Water: yes
89
Can this molecule for a hydrogen bind with itself and with water
Itself : no Water: yes
90
Can this molecule form a hydrogen bond with itself and with water ?
Itself : no Water: no (no lone pair on N atom)

a level chemistry (9 decks)

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