Module 3 Flashcards

1
Q

Why are group 1 & 2 elements classified as s-block elements?

A

Their highest energy electron(s) are in an s-orbital or sub-shell.

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2
Q

Why can elements be classified as p-block elements?

A

Their highest energy electron(s) are in a p-orbital or sub-shell.

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3
Q

Why can elements be classified as a d-block element?

A

Their highest energy electron(s) are in a d-orbital or sub-shell.

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4
Q

What is meant by the term first ionisation energy?

A

The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions.

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5
Q

What are the three factors that affect ionisation energy?

A
  • atomic radius
  • nuclear charge
  • electron shielding
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6
Q

What is the general trend in ionisation energy across a period? Explain why.

A
- ionisation energy increases
Due to:
- atomic radii decrease
- increase in nuclear charge
- increase in nuclear attraction
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7
Q

What is the general trend in ionisation energy down a group? Explain why.

A
- ionisation energy decreases
Due to:
- increase in atomic radii
- increase in electron shielding
- decrease in nuclear attraction
* increase in nuclear charge is outweighed!
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8
Q

Why is there a small decrease in ionisation energy between elements in group 2 to 3?

A
  • group 3 elements have outer electron in a p-orbital, slightly further from the nucleus and easier to remove
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9
Q

Why is there a small decrease in ionisation energy between elements in group 5 to 6?

A
  • group 6 elements start to have their electrons spin-pair, small repulsion between paired electrons and easier to remove
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10
Q

What is meant by the term metallic bonding?

A

Electrostatic force of attraction between positive metal ions and delocalised electrons.

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11
Q

What is the trend in reactivity down group 2? Explain why.

A
  • reactivity increases

- atomic radius increases and electron shielding increases, electrons easier to remove

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12
Q

What is the trend in solubility down group 2? What is the effect on pH?

A
  • solubility increases

- resulting solutions are more alkaline, higher pH

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13
Q

What is calcium hydroxide used for?

A

“Lime” to neutralise acidic soil

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14
Q

What is magnesium hydroxide used for?

A

Milk of magnesia to neutralise excess stomach acid

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15
Q

What is calcium carbonate used for?

A

Limestone as a building material

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16
Q

What is the limitation for the use of calcium carbonate in buildings and statues?

A

Reacts with acids in rainwater leading to erosion

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17
Q

What is the trend in boiling points down group 7? Explain why.

A
  • increase

- London forces increase with increasing number of electrons

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18
Q

What is the trend in reactivity down group 7? Explain why.

A
  • decreases
  • increase in atomic radius
  • increase in electron shielding
  • ability to gain electron decreases due to increased repulsion
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19
Q

What is meant by the term disproportionation?

A

The oxidation and reduction of the same element in a redox reaction.

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20
Q

What colour is chlorine in both water and cyclohexane?

A

Pale green in both

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21
Q

What colour is bromine in both water and cyclohexane?

A

Orange in both

22
Q

What colour is iodine in water and cyclohexane?

A

Brown in water

Violet in cyclohexane

23
Q

Why is chlorine used to treat drinking water?

A

Kills bacteria, makes it safe to drink

24
Q

What are the disadvantages of using chlorine to treat drinking water?

A

Possible source of toxic chlorine gas, risk of forming chlorinated hydrocarbons

25
Q

What are the results of testing for the haloed ions using silver nitrate solution?

A
Chloride = white precipitate
Bromide = cream precipitate
Iodide = yellow precipitate
26
Q

What are the results of testing the precipitates formed from the reaction of halide ions with silver nitrate solution when tested with ammonia?

A
  • Dilute ammonia - White precipitate dissolves
  • Conc. ammonia - cream precipitate dissolves
  • yellow precipitate will not dissolve on addition of ammonia
27
Q

What is meant by the term activation energy?

A

The minimum energy required to start a reaction by breaking bonds in the reactants.

28
Q

What are the standard conditions?

A

100 kPa
298 K
Solutions 1 mol/dm3

29
Q

What is meant by the term enthalpy change of formation?

A

The energy change that takes place when one mole of a compound is formed from its constituent elements in their standard states under standard conditions.

30
Q

What is meant by the term enthalpy change of combustion?

A

The energy change that takes place when one mole of a substance is completely combusted.

31
Q

What is meant by the term enthalpy change of neutralisation?

A

The energy change associated with the formation of one mole of water from a neutralisation reaction, under standard conditions.

32
Q

Why might the value for average bond enthalpy differ from the actual bond enthalpy?

A

The same bond in a different species may require a different amount of energy to break it, the average takes into account all different values for that type of bond.

33
Q

How is the Periodic Table arranged?

A
  • by increasing atomic number
  • in periods showing repeating trends in physical and chemical properties
  • in groups having similar chemical properties
34
Q

What are the factors that affect rate of reaction?

A
  • temperature
  • pressure (gas only)
  • concentration
  • surface area
  • catalysts
35
Q

How do an increase in pressure or concentration result in an increase in the rate of a reaction?

A

FESC = more particles, more frequent collisions, more successful collisions, faster rate

36
Q

How can reactions be monitored in order to calculate their rate of reaction?

A
  • collecting volume of gas
  • measuring mass throughout
  • time taken for visible change
  • colorimeter to measure conc.
37
Q

What is meant by the term catalyst?

A

A substance that increases the rate of reaction without being used up during the process (it is regenerated). Provides an alternative pathway with a lower activation energy.

38
Q

What is meant by the term homogeneous catalyst?

A

A catalyst used in a reaction which is in the same phase as the reactant.

39
Q

What is meant by the term heterogeneous catalyst?

A

A catalyst used in a reaction which is in a different phase from the reactant.

40
Q

What are the advantages of using catalysts?

A
  • lower energy demands
  • reduce costs of processes
  • better for environment, less fossil fuels burned
  • lower carbon dioxide emissions
41
Q

What are the disadvantages of using catalysts?

A
  • can contain toxic substances
  • hard/costly to obtain
  • may still require high pressures and temps.
42
Q

What are the key features of the Boltzmann distribution?

A
  • area under curve = total number of molecules (constant)
  • no molecules with no energy (starts at origin)
  • no maximum energy (does not touch x axis)
  • only molecules with energy greater than Ea will react
43
Q

What is meant by the term dynamic equilibrium?

A

The equilibrium that exists in a closed system when the rate of the forward reaction is equal to the rate of the reverse reaction and all the chemicals have their concentrations maintained.

44
Q

What happens to the position of equilibrium when the concentration is increased?

A

Equilibrium will shift to use excess (away from increase)

45
Q

What happens to the position of equilibrium when the concentration is decreased?

A

Equilibrium will shift to replace the decrease (shifts towards change)

46
Q

What will happen to the position of equilibrium if temperature is increased?

A

Shifts towards endothermic side

47
Q

What happens to the position of equilibrium when temperature is decreased?

A

Shifts towards exothermic side

48
Q

What happens to the position of equilibrium when pressure is increased?

A

Shifts towards side with fewest moles of gas

49
Q

What happens to position of equilibrium when pressure is decreased?

A

Shifts towards side with most moles of gas

50
Q

Why do catalysts have no effect on position of equilibrium?

A

Speed up rate of both forward and reverse reactions by the same amount

51
Q

What can be concluded about the position of equilibrium if the value of Kc is large?

A

Favours product side

52
Q

What can be concluded about the position of equilibrium if the value of Kc is small?

A

Favours reactant side