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Chemistry > Giant Structure > Flashcards

Giant Structure Flashcards

1
Q

Name 3 methods of proving ion existence

A

Electrolysis
Ion migration
X-ray crystallography

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2
Q

How does electrolysis prove ion existence

A

aq/l
Conduct electricity
Free delocalised electrons to carry charge

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3
Q

How does ion migration prove ion existence

A

aq coloured ions
Copper chromate solution soaked paper
Crocodile clips, DC power supply
Blue copper cations, yellow chromate anions

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4
Q

How does X-ray crystallography prove ion existence

A

Diffract through slag crystal
Electron density map
Contours link equal charge regions
Separate ionic solid entities

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5
Q

Lattice energy

A

Energy change to make 1 mole of a solid ionic crystal from its gaseous ions
Exo

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6
Q

Standard enthalpy change of formation

A

Energy change to make 1 mole of a compound from it’s elements in their standard state under standard conditions

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7
Q

Standard enthalpy change of atomisation

A

Energy change to make 1 mole of gaseous atoms from it’s elements in their standard state under standard conditions
Endo

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8
Q

Ionisation energy

A

Energy to remove 1 electron from each atom/ion in 1 mole of gaseous atoms/ions
Endo

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9
Q

Electron affinity

A

Energy change to add 1 electron to each atom/ion in 1 mole of gaseous atoms/ions

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10
Q

Describe the energetics pattern of electron affinity

A

From neutral = exo
From negative = endo
Negative charge of ion and negative charge of electron repel each other, energy must be absorbed to overcome the ESR

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11
Q

Describe the 3 general layers of a borne haber cycle

A

Natural elements
Gaseous ions
Solid lattice

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12
Q

Describe the differences (4) between a BHC of NaCl and MgCl2

A

Higher IEs
Higher No.IEs
Higher lattice enthalpy
Double Cl values

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13
Q

Name 3 factors that effect LE

A

Charge of ions
Size of ions
No. Ions

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14
Q

BHC exam technique terminology

A

X larger/smaller
More Endo/exo
State what is

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15
Q

How does charge effect LE

A

Higher charge
Higher ESA between ions
Higher ETO
More exo LE

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16
Q

How does ion size effect LE

A

Larger size
Ions further away
Less ESA
Less exo LE

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17
Q

Exam technique factors effecting LE

A

State what’s the same and what’s different

18
Q

What’s influences theoretical LE

A

Ion attraction/repulsion

19
Q

How do you calculate the theoretical LE

A

Charges + distance between ions —> sum of forces

20
Q

Describe 3 reasons why theoretical LE is calculated

A

BH experimental data doesn’t exist
Use in BH to find (usually) less exo enthalpy of formation for unexpected compounds
Compare T + E, find validity, more than 10% difference = insufficient model, usually covalent bonding present

21
Q

Describe metallic bonding structure

A

Close packed giant lattice of positive ions and a sea of delocalised electrons
Held together by ESA between positive ions and negative electrons

22
Q

Name 3 properties of metallically bonded structures

A

High mp/bp
Malleable
Electrical conductor

23
Q

Why are metallic structures malleable

A

Same layers
Movement doesn’t change bonding

24
Q

Why are metallic structures electric conductors

A

Delocalised electrons from ions carry charge through substance

25
Q

Why do metallic structures have high mp/bp

A

Giant structures
Many strong bonds
More ETO

26
Q

Enthalpy change of solution

A

Enthalpy change for 1 mole of a substance to dissolve in water to become a solution of infinite dilution

27
Q

Enthalpy change of hydration

A

Enthalpy change for 1 mole of gaseous ions to dissolve in water to become a solution of infinite dilution

28
Q

Describe the appearance of a hydrated ion

A

Ion surrounded by opposite charge atoms of water molecules

29
Q

Describe what happens when an ionic solid dissolves in water

A

Crystal lattice broken (endo)
Water H bonds broken (endo)
H point at cation
O point at anion
ESA (exo)
Hydration

30
Q

Describe a hydration cycle

A

Gaseous ions at top
Aqueous ions in middle
Solid lattice at bottom

31
Q

Why is finding the enthalpy of solution from a hydration cycle unreliable (4)

A
  • Small difference between 2 much larger values that can’t be directly found and are effected by charge and size factors
  • Small % uncertainty in LE of hydration enthalpy can —> large solution enthalpy % uncertainty
  • Solution enthalpy isn’t only solubility factor, endo solution enthalpy won’t dissolve well, large LE
  • Soluble compounds can form saturated solution
32
Q

Why does poor E + T LE agreement occur

A

Polarisation of anion by cation
Cation distorts electron cloud on anion
Pulls towards shared region
Nearly electron sharing
Some covalent character
Stronger bonding
ELE more exo than TLE suggests

33
Q

Anion and cation properties in polarisation

A

Cation, polarising power
Anion, polarisability

34
Q

What factors INCREASE polarising power of cation

A

Increase cation charge
Decrease cation size
Higher positive charge density = more effective distortion

35
Q

What factors INCREASE polarisability of anion

A

Increase charge
Increase size
Larger ion = less grip on outer electrons = easier to distort

36
Q

Name 4 levels on bonding spectrum

A

Pure covalent
Polar covalent (unequal shared electrons)
Polar ionic (distorted ions)
Pure ionic

37
Q

Name 3 allotropes of carbon

A

Diamond
Graphite
Graphene

38
Q

Graphite 4 properties 2 uses

A
  • Conductor, delocalised electrons between layers
  • Sheet formation
  • Each C bonded to 3 others
  • Soft, layers can slide
    Uses, electrics, pencils
39
Q

Diamond 7 properties

A
  • All Cs cov bonded to 4 others
  • Tetrahedral structure
  • High mp, lots ETO, many bonds
  • Hard, strong bonds, lattice arrangement
  • Thermal conductor, vibrations travel through stiff lattice
  • Insoluble, more attracted to neighbouring atoms that solvent molecules, no ions
  • Not electrical conductor, no free electrons/ions
40
Q

Graphene 6 properties

A

One sheet of graphite, joined by 2 hexagons
2D, one atom thick
Conductor, delocalised electrons
Strong
Transparent
Light

Chemistry (24 decks)

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