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A-Level Chemistry > Group 2 and Halogens > Flashcards

Group 2 and Halogens Flashcards

1
Q

What happens to reactivity down group 2?

A

It increases

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2
Q

Why does group 2 reactivity increase down the group?

A

Size of metal atom increases
Shielding increases
Outer electrons require less energy to remove
Since nuclear attraction decreases

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3
Q

What happens to alkalinity down group 2?

A

Increases

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4
Q

Why does group 2 alkalinity increase down the group?

A

Metal hydroxides are more soluble

So put more OH- into solution

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5
Q

What do metal hydroxides react with water to form?

A

White precipitate

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6
Q

What are group 2 compounds used for?

A

Indigestion
Agriculture
Medicine

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7
Q

What group 2 compound is used to treat indigestion?

A

Gaviscon - CaCO3

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8
Q

Why are group 2 compounds used in agriculture?

A

To treat acidic soil with alkaline

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9
Q

What group 2 compound is used to treat acidic soil?

A

Ca(OH)2 (known as lime)

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10
Q

Why are group 2 compounds used in medicine?

A

Insoluble so shows up in X-rays

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11
Q

What group 2 compound is used in medicine?

A

Barium (barium meal)

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12
Q

Metal + water?

A

Metal hydroxide + hydrogen

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13
Q

Metal + acid?

A

Metal salt + hydrogen

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14
Q

Metal + oxygen?

A

Metal oxide

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15
Q

Metal carbonate + acid?

A

Metal salt + water + carbon dioxide

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16
Q

Metal oxide + water?

A

Metal hydroxide

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17
Q

What is the appearance of F as a RT?

A

Pale yellow gas

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18
Q

What is the appearance of Cl as a RT?

A

Green gas

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19
Q

What is the appearance of Br as a RT?

A

Red-brown liquid

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20
Q

What is the appearance of I as a RT?

A

Grey solid

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21
Q

What is the appearance of F vapour?

A

Colourless

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22
Q

What is the appearance of Cl vapour?

A

Colourless

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23
Q

What is the appearance of Br vapour?

A

Orange vapour

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24
Q

What is the appearance of I vapour?

A

Purple vapour

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25
Q

Which is the most reactive halogen?

A

F

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26
Q

What happens to melting/boiling point down group 7?

A

Increases

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27
Q

Why does the melting/boiling point increase down group 7?

A

Halogen molecule size increases down the group
Greater London forces between molecules
So more energy needed to separate molecules

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28
Q

What happens to electronegativity down group 7?

A

Decreases

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29
Q

Why does electronegativity decrease down group 7?

A

Atomic radius increases
Shielding increases
Nuclear attraction reduced

30
Q

Describe astatine

A

Radioactive
Strong oxidising agent
State at RT = solid
Electronegativity = lowest

31
Q

What happens to reactivity down group 7?

A

Decreases

32
Q

Why does reactivity decrease down group 7?

A

Atomic radius increases
Shielding increases
Nuclear attraction decreases
Gaining electrons = harder

33
Q

Are halogens strong oxidising agents?

A

YES

34
Q

Are the halogens the most reactive non-metals?

A

YES

35
Q

What is cyclohexane (organic solvent) used for?

A

To distinguish between Br2 and I2

36
Q

What are the three anion (negative ion) tests?

A

Carbonate
Sulfate
Halide

37
Q

How do you test for carbonate ions?

A

Add dilute nitric acid to solid or solution

Bubble any gas made into limewater

38
Q

What is the positive test for a carbonate test?

A

Cloudy

39
Q

How do you test for sulfate ions?

A

Add dilute HCl

Add barium chloride/nitrate solution

40
Q

What is the positive test for a sulfate test?

A

White precipitate

41
Q

How do you test for halide ions?

A

Add dilute nitric acid

Add aqueous silver nitrate

42
Q

What is the positive tests for a halide test?

A 
Cl*- = white
Br*- = cream
I*- = yellow
43
Q

What is the ionic equations for halide test?

A

Ag+ (aq) + Cl-(aq) —–> AgCl(s)

REPEAT FOR OTHER HALIDES

44
Q

How do you further test for halide ions?

A

Add aqueous ammonia

45
Q

What is the positive tests from the further halide tests?

A 
Cl*- = soluble so precipitate redissolves
Br*- = soluble so precipitate redissolves
I*- = insoluble
46
Q

What is the sequence for anion test?

A

Carbonate
Sulfate
Halide

47
Q

Why is carbonate test done first?

A

As sulphates and halides don’t produce a gas with acid

48
Q

Why is sulfate test done second?

A

To remove carbonates since barium carbonate can also produce a white precipitate

49
Q

Why is halide test done last (third)?

A

To remove carbonate and sulfate as both insoluble in water

50
Q

What is the test for cations (positive ions)?

A

Ammonium ions test

51
Q

How do you test for ammonium ions?

A

Add aqueous NaOH
Gently warm
Hold warm litmus pH paper above

52
Q

What is the positive test for ammonium ions?

A

Litmus pH paper turns blue

53
Q

What does it mean that halogens act as oxidising agents?

A

Oxidises halide ion
Gains electrons
Reduced to form halide ion

54
Q

What happens to oxidising ability down group 7?

A

Decreases

55
Q

What is chlorine used to do?

A

Purify water

56
Q

What are the risks associated with chlorine?

A

It’s toxic to humans so risks associated with gas leaks

57
Q

What the formula for chloric (I) acid?

A

HOCl

58
Q

What is the formula for bleach?

A

NaOCl Sodium chlorate

59
Q

What is the equation for the production of chloric (I) acid?

A

Cl2 + H2O —-> HCl + HOCl

60
Q

What is the equation for the production of bleach?

A

Cl2 + NaOH —-> NaCl + NaOCl + H2O

61
Q

What are the ionic equations for the reactions?

A

2Br- (aq) + Cl2 (aq) —-> 2Cl- (aq) + 2Br2 (aq)

62
Q

What colour is Cl2 water?

A

Colourless

63
Q

What colour is Br2 water?

A

Yellow

64
Q

What colour is I2 solution?

A

Orange/brown

65
Q

What colour is Br2 in cyclohexane?

A

Orange

66
Q

What colour is I2 in cyclohexane?

A

Purple/violet

67
Q

Describe the colour changes in Cl2 water?

A

Cl2 - NO REACTION
Br2 - colourless —-> yellow Cl2 became KCl so water became yellow
I2 - colourless —-> orange/brown ^^^^^

68
Q

Why does Cl2 have the strongest oxidising strength?

A

Has smallest atomic radius
Less shielding
So greater attraction for electron

69
Q

What happens when Cl displaces KX?

A

Cl2 oxidises the X and reduces its self

70
Q

Describe the colour changes in BR2 water?

A

Cl2 - colourless —-> yellow Br2 can’t displace Cl2 so NO REACTION and Br2 stays Br2 water
Br2 - NO REACTION
I2 - colourless —-> orange/brown Br2 can displace KI so I2 becomes I2 solution

71
Q

Describe the colour changes in I2 solution?

A

Cl2 - colourless —-> orange/brown can’t displace so NO REACTION
Br2 - colourless —-> orange/brown ^^^^^
I2 - NO REACTION

72
Q

In which reactions does displacement occur?

HINT: 3

A

Cl2 water with Br2 and I2

Br2 water with I2

A-Level Chemistry (26 decks)

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