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Wjec Chemistry Unit 1 > 1.6 > Flashcards

1.6 Flashcards

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1
Q

Oxidation is

A

Loss of electrons

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2
Q

Reduction is

A

Gain of electrons

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3
Q

All elements have an oxidation number of

A

0

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4
Q

Hydrogen’s oxidation number in compounds is usually

A

+1

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5
Q

Oxygen’s oxidation number in compounds is usually

A

-2

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6
Q

Group 1 and 2 elements’ oxidation number are

A

+1 and +2

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7
Q

Oxidation number of the elements in a compound must add up to

A

0

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8
Q

Oxidation number of the elements in an ion must add up to

A

The charge

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9
Q

S-block and oxygen/ air

A

Solid white Oxides

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10
Q

Group 2 and acid

A

Salt

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11
Q

Trend in reactivity of s block elements down the group

A

Increases
All react vigorously with acids
React with oxygen and burn in air
Caesium inflames spontaneously

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12
Q

Is G1 or G2 more reactive

A

G1- easier to lose 1 electron than 2

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13
Q

All oxides and hydroxides of s block elements are

A

Basic

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14
Q

All salts of which group are soluble

A

Group 1

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15
Q

Describe trend in solubility of group 2 hydroxides

A

Increases down the grouo

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16
Q

Describe the trend in group 2 sulphates

A

Decreases down the group

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17
Q

Solubility of group 2 carbonates

A

Insoluble

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18
Q

Solubility of group 2 nitrates

A

Soluble

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19
Q

Flame colour of Li

A

Red

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20
Q

Flame colour of sodium

A

Yellow/orange

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21
Q

Flame colour of potassium

A

Lilac

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22
Q

Flame colour of calcium

A

Brick red

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23
Q

Flame colour of strontium

A

Crimson res

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24
Q

Flame colour of barium

A

Apple green

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25
Q

Flame colour of magnesium

A

Bright white

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26
Q

Trend in thermal stability of Group 2 hydroxides and carbonates

A

Increases down the group

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27
Q

Colour of all s-block salts

A

White

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28
Q

What is volatility

A

How readily a substance vapourises

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29
Q

Trend in volatility of halogens

A

Decreases down the group - stringer intermolecular forces

30
Q

Halogens at room temperature

A

Cl - green has
Br - red/brown liquid
I - grey solid

31
Q

Trend in reactivity of halogens

A

Decreases down the group

Harder to attract electrons as theres more shielding and further from the nucleus

32
Q

Trend in oxidising power of halogens

A

Decreases down the group

Harder to attract electrons as more shielding and further from nucleus

33
Q

Iron wool burning in halogens vapour

A 
Chlorine and bromine - iron(III) halide
      2Fe + 3X2 ---> 2FeBr3
Iodine - iron (II) iodide
     Fe + I2 ---> FeI2
    Less reactive and a weaker oxidising agent
34
Q

What is the test for halogens

A

Silver nitrate test

35
Q

Describe the silver nitrate test

A
  • add few drops of nitric acid to ensure all other anions removed
  • silver nitrate is added to create an insoluble silver halide
  • to distinguish further aqueous ammonia is added to the precipitate
36
Q

Results if adding silver nitrate to halides

A

Cl- White precipitate
Br- Cream precipitate
I- Pale yellow precipitate

37
Q

Results of adding aqueous ammonia to insoluble silver halide

A

AgCl Dissolves in dilute ammonia
AgBr Dissolves in concentrated ammonia
AgI Insoluble in concentrated ammonia

38
Q

Why is there a decreasing oxidising power down group 7

A

Increasing atomic radius

Increased shielding

39
Q

On strong heating, magnesium reacts with steam to give magnesium oxide and hydrogen.
Explain why magnesium hydroxide is not produced at this temperature

A

Magnesium hydroxide thermally decomposes at this temperature to form the oxide

40
Q

Explain why the elements in group 7 become less volatile down the group

A

The molecular size increases down the group
There are stronger VDW forces
These require more energy to break

41
Q

Give one test, and the expected results, which could be used to show the presence of calcium ions in the solution calcium nitrate

A

Flame test - brick red

42
Q

Give a description of the flame test

A

Wet a splint in a HCl solution then dio it in the powder before putting it above a bunsen burner

43
Q

Would you expect strontium sulphate to be soluble in water - why?

A

No as sulphates become less soluble down group 2

44
Q

State and explain how the reactivity of the elements in group 7 varies down the group

A

Decreases
They react by gaining 1 electron
But as there is extra shielding and increases atomic radius it makes it harder to do so

45
Q

State the reagents and observations for the test to show the presence of the sulphate ions in a solution

A

Barium chloride

White precipitate

46
Q

Describe what is seen when aqueous iodide ions are added to a solution which contains aqueous chlorine. Give an explanation for your observation.

A

Red/brown solution

I- oxidised by Cl to brown iodine

47
Q

State, giving a reason, whether chlorine, Cl, is a stronger or weaker
oxidising agent than bromine, Br

A

Stronger

Due to having a stronger electronegativity value so the oxidising power decreases down the group

48
Q

Write a balanced equation for the reaction of calcium with water

A

Ca + 2H2O —> Ca(OH)2 + H2

49
Q

Describe the trend in melting and boiling temperature across a period

A
  • general increase from first to fourth element - metallic bonding
  • large decrease to the fifth - giant covalent
  • small general decrease to the eighth element - simple molecular covalent
50
Q

What is an oxidising agent

A

Species that accepts electrons

Becomes reduced itself

51
Q

What is a reducinh agent

A

Species that donates electrons

Becomes oxidised itself

52
Q

Group 1 and water

A
  • hydroxide and hydrogen formes
  • react vigorously with cold water
  • becomes more vigour as you go down the group
53
Q

What can be seen when Lithium reacts with cold water

A

It floats, fizzes and moves

54
Q

What can be seen when sodium react with cold water

A

Floats, fizzes, moves and melts

55
Q

What can be seen when potassium reacts with cold water

A

Floats, fizzes, moves, melts and burns

56
Q

Group 1 or 2 react less vigorously with water

A

Group 2

57
Q

Magnesium with cold water

A

Slow

58
Q

Calcium and cold water

A

Steady stream of bubbles and a white precipitate of calcium hydroxide forma

59
Q

Group 2 and cold water

A

The Hydroxide and hydrogen

60
Q

Why does the reactivity fo group 2 elements increase down the group

A

Ionisation energies decreases down the group so energy needed to form carions decreases

61
Q

Why are group 1 metals more reactive than group 2 metals

A

Only need to lose one electron compared to losing two

62
Q

Which kind of s block elements react with water to form a soluble hydroxide or alkali

A

Group 1 oxides and barium oxide

63
Q

S block metal oxides

A

Strong bases

64
Q

S block hydroxides

A

Alkalis as they’re soluble

65
Q

Group 1 solubility

A

Soluble

66
Q

Trend in group 2 sulfates solubility

A

Less soluble down the group

67
Q

Product of group 2 hydroxides decomposing on heating

A

The oxide and steam

68
Q

Product of group 2 carbonates on heating

A

The oxide and carbon dioxide

69
Q

Test for trend of group 2 carbonates

A

Heating them and seeing how long it takes for the carbon dioxide formed to turn limewater cloudy

70
Q

Trend in melting and boiling temperatures of halogens and why

A

Increases down the group

Increase in electrons, increase in induced dipole - induced dipole forces

71
Q

Insoluble salt formation

A
  • precipitation reaction
  • two suitable solutions are mixed to form a soluble salt and an insoluble salt
  • precipitate is filtered, washed and dried
72
Q

Soluble salt formation

A
  • usually can neutralise an acid
  • excess solid is filtered
  • solution is evaporated and left to cool to form crystals

Wjec Chemistry Unit 1 (9 decks)

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