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N Chemistry A Level > Topic 2 Bonding & Structure > Flashcards

Topic 2 Bonding & Structure Flashcards

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1
Q

What angle is linear?

A

180
No lone pair, furthest repel

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2
Q

What angle is V shape?

A

104.5
2 lone pairs

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3
Q

What angle is trigonal planar?

A

120
No lone pairs

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4
Q

What angle is trigonal pyramidal?

A

107
1 lone pair

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5
Q

What angle is tetrahedral?

A

109.5
No lone pairs

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6
Q

What angle is trigonal biphramidal?

A

5 bonds formed
90 in 2
120 in 3

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7
Q

What angle is hexagonal?

A

90 between every 2 bonds
6 bonds in total

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8
Q

What is an ionic bond?

A

Strong electrostatic attraction between opposite charged ions

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9
Q

What is the ionic attraction affected by?

A

Ionic radius (smaller=stronger)
Ionic charge (higher=stronger)

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10
Q

Qualities of ionic bonds

A

High mp
Soluble in water
Poor electron conductivity when solid but good when molten
Brittle

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11
Q

How are ionic bond qualities proven?

A

Electrolysis

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12
Q

What are covalent bonds? (2 marks)

A

Strong electrostatic attraction (1)
Between 2 nuclei and the share of pair of electrons (1)

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13
Q

What do σ bonds look like?

A

Overlap of s orbitals
2 O O overlapping
Or 1 s 1 p (O ∞ overlap)
Or ∞ ∞ overlap

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14
Q

What do π bonds look like?

A

8 8 overlap
2 p orbital overlapping sideways so 2 areas where electrons are shared

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15
Q

What is the definition of electronegativity?

A

Ability for an atom to attract bonded pair of electrons from covalent bonds

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16
Q

What is a dative covalent bond?

A

Empty orbital of one atom overlap with an orbital with lone pair
(Donating a lone pair to an empty orbital)

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17
Q

What are examples of dative covalent bonds? Give 2

A

NH4+ (N donates to H)
Al2Cl6 (Cl donates to Al)

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18
Q

When u see mp/bp what do u think of?

A

London forces
PDPD
H bonds

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19
Q

Why can’t S form H bonds?

A

Not electronegative enough, much less electronegative than O
, doesn’t form very polar bonds like F O N

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20
Q

The structural feature that graphene and graphite have in common is that the carbon atoms are arranged in…

A

Hexagonal rings within a layer

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21
Q

What is the bond angle in BF3?

A

120

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22
Q

What are the strongest interactions between molecules in solid boric acid? (H3BO3)

A

Hydrogen bonds

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23
Q

How to find out the succession ionisation energies and their groups?

A

Biggest jump
Eg from 2 to 3 then it must be a G2 element

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24
Q

How to determine isoelectronic ion size?

A

For atoms or ions that are isoelectronic, the number of protons determines the size. The greater the nuclear charge, the smaller the radius in a series of isoelectronic ions and atoms

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25
Q

Ionic bonding is the strong electrostatic attraction between….

A

Cations and anions
(There are NO delocalised e-s in ionic bonds!)

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26
Q

What does HCl exist at room temperature as?

A

Giant lattice of oppositely charged ions
(Gas)

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27
Q

What are the bond angles within a layer of graphene and a layer of graphite?

A

All 120

28
Q

How is a dative covalent bond formed in NH3BF3?

A

Lone pair donated from N
BF3 accepts the lone pair and forms a full outer shell

29
Q

What’s the bond angle and name when there is a lone pair and 3 bonds?

A

107
Trigonal pyramidal

30
Q

What’s the bond angle and name when there are 4 bonds?

A

Tetrahedral
109.5

31
Q

Why is the mp of silicon(IV) dioxide way higher than iodine when both of them are covalent bonded?

A

Silicon oxide is a giant structure so contains many strong covalent bonds (1)
Iodine only has weak London forces (1)
More energy is needed to break silicon dioxide

32
Q

Why do both water and carbon dioxide have polar bonds but only water is a polar molecule? 4 marks

A

Oxygen is more electronegative than both H and C, so arrow points towards O
So polar bonds are formed, O is delta negative, C and H are delta positive
Water has V-shape, so vectors don’t cancel out
CO2 has linear shape, vectors cancel

33
Q

In terms of bonding and structure, why is the melting point of silicon way higher than chlorine when both are Period 3 elements?

A

Silicon: giant molecular, strong covalent bonds, lots of energy needed to break
Chlorine: simple molecular, diatomic and has weak London Forces

34
Q

Graphite vs graphene

A

Both hexagonal layer with C joined with 3 other C
London forces hold graphene layers together and make graphite
Unbonded Cs have delocalised electrons that are free to move

35
Q

Describe structure of diamond

A

Each C joined with 4 other C by covalent bonds
Regular Tetrahedral structure
No free electrons
Giant covalent lattice structure

36
Q

Why is lots of energy needed to break CaCO3?

A

Because of strong bonds within the carbonate ion

37
Q

Why is more energy required to break AlF than AlCl? (In terms of electronegativity) (6 marks)

A
  • larger electronegativity difference between Al and F than Al and Cl
  • AlCl mostly simple covalent
  • AlF more polar
  • AlCl more weaker London forces/intermolecular
  • AlF is giant structure, strong electrostatic attraction between ions
  • more energy needed to break stronger bonds
38
Q

What’s the only covalently bonded compound with a metal in it?

A

AlCl

39
Q

What’s the order of strength of bonds?

A

H bonds > PDPD > London

40
Q

Why is methanol and water ‘soluble in all proportions’?

A

Methanol forms H bonds with water
At least 1 lone pair on oxygen atom at 180 degrees

41
Q

What are 2 elements with special electronic configurations?

A

Copper and chromium

42
Q

What is it mean by hydrogen bonds? 2 marks

A

Hydrogen atom forming evident bond in the same or different molecule
With another atom (F,O or N) that is more electronegative than H

43
Q

What is a metallic bond? 2 marks

A

Electrostatic attraction between metal cation and delocalised electrons (outer shell electrons)

44
Q

Why is magnesium a better electric conductor than sodium?

A

Mg is a smaller ion and has 1 extra delocalised electron than Na (group 2 vs group 1)

45
Q

Why is nitrogen much less reactive than carbon monoxide and hydrogen cyanide? (Given they are isoelectronic) (1 mark)

A

N has triple bonds with diatomic N, much stronger than C=O, C (triple) N, C-H
N2 also non polar, while the other two are polar

46
Q

Why is sodium chloride soluble in water? 3 marks

A
  • energy to overcome electrostatic attraction between sodium cation and chloride anion
  • lattice breaks down and ions are separated
  • energy supplied by hydration of ions by water molecules
47
Q

What structure is sodium chloride?

A

Lattice ionic structure

48
Q

What is it meant by a polar bond? How does polarity arise?

A
  • there is a charge separation between molecules of a bond , one is δ+ and one is δ-
  • when bond formation and one molecule is more electronegative than the other
  • electron cloud produce higher electron density towards electronegative element
49
Q

What is a Hydrogen bond like?

A

Very polarised
high charge density

50
Q

Why does melting point in G2 decrease down?

A

atomic size increases so metallic bond becomes weaker, making it easier for them to slide past each other

51
Q

Why does electronegativity decrease down G7?

A

the number of electron shells increases down, so larger atomic radius.
Hence weaker attraction for electrons, making it harder to attract them, hence lower electronegativity.

52
Q

Predict state of astatine in standard conditions and why.

A

Solid
Because of increasing London forces down G7 (NOT mp/bp!)

53
Q

Why is ice less dense than water in terms of hydrogen bonds? (2 marks)

A
  • more space between molecules
  • due to 3D lattice structure in ice
  • H bonds are stronger than covalent bonds
54
Q

Which element has the highest bp in Period 3? (1 mark)

A

Si

55
Q

What does white phosphorus consist of?

A

small molecules

56
Q

What cation would be most polarising?

A

High charge
small radius

57
Q

Why is the electrical conductivity of pure silicon very low?

A

Because there are no free delocalised electrons
all of Si’s free electrons are used to form covalent bonds

58
Q

Explain the high melting temperature of Silicon in terms of bonding. (2 marks)

A

Lot of strong covalent bonds (1) needed to be broken by lots of energy to overcome (1)

59
Q

How to work out if an ion has the largest ionic radius in a MCQ?

A

least num of proton : electron ratio
so least attraction

60
Q

How to work out if an ion has the smallest ionic radius in a MCQ?

A

most num of proton : electron ratio
so most attraction

61
Q

In terms of orbital overlap, a double bond is

A

a σ and π bond

62
Q

What is the C-C-C bond angle in a cycloalkane?

A

109.5°

63
Q

Which Intermolecular Force is the strongest?

A

Hydrogen bonds!!!

64
Q

Deduce 2 possible reasons why there are 2 widely different values for the compressive strength of graphite. (2 marks)

A
  • due to lower values of london forces
  • stronger C-C bonds
65
Q

How do you explain sodium sulfide dissolving in water?

A

Energy released when sodium ions and sulfide ions are hydrated is greater than energy required to break the attraction between sodium ions and sulfide ions

66
Q

Why does HCl (g) not conduct but HCl (aq) conduct electricity?

A

Covalent bond in HCl (g) changes to ionic bond in aqueous solution

67
Q

What is observed when HCl is added to Na2CO3? (2 marks)

A

Solid dissolves
Effervescence

N Chemistry A Level (19 decks)

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