Group 7 Flashcards

1
Q

What are the Halogens? (fluorine, chlorine, iodine)

A

Reactive non-metallic elements of the p-block

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2
Q

what is the definition of volatility?

A

How easily a substance turns from a liquid into a gas

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3
Q

what happens to volatility as you go down the group?

A

The elements become less volatile as you go down the group

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4
Q

what happens to intermolecular forces as we descend group 7?

A

The intermolecular forces between the molecules of the halogens increases

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5
Q

what happens to induced dipole dipole interactions as you go down the group?

A

-they increase due to the molecules containing more electrons
-More energy is required to break the induced interactions between the molecules

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6
Q

what is the bond type in the halogen molecule?

A

Covalent

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7
Q

What do you halogens exist as?

A

Diatomic molecules

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8
Q

What is the structure of the halogens?

A

Simple molecular

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9
Q

what happens to boiling point as you go down the group? (7)

A

Increases

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10
Q

What happens to the intensity of the colour of the halogens, as you go down the group?

A

Increases

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11
Q

why would astatine be expected to react similarly to other halogens?

A

-they all have similar properties

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12
Q

What happens to an oxidising agent?

A

Gets reduced

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13
Q

what does a halogen atom readily accept an electron to form?

A

-a halide ion with a full outer shell of electrons (this is a stable arrangement)

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14
Q

what do all halogens act as?

A

oxidising agents

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15
Q

what is the most powerful oxidising agent?

A

fluorine

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16
Q

what happens to oxidising power as you go down group 7?

A

-Decreases- this is because as you go down nuclear attraction decreases as there is more shielding and shells making it harder to lose an electron

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17
Q

what colour is produced when chlorine is placed in an aqueous solution?

A

pale green

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18
Q

what colour is produced when bromine is placed in an aqueous solution?

A

orange

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19
Q

what colour is produced when iodine is placed in an aqueous solution?

A

brown

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20
Q

what colour is produced when chlorine is placed in an organic solvent ?

A

pale green

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21
Q

what colour is produced when bromine is placed in an organic solvent?

A

orange/brown

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22
Q

what colour is produced when iodine is placed in an organic solvent ?

A

purple

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23
Q

What is the displacement reaction?

A

reaction in which a more reactive element displaces a less reactive element from an aqueous solution of the latter’s ions

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24
Q

What can the decrease in the reactivity of the elements as you go down the group be demonstrated by?

A

-Displacement reactions of aqueous halides using chlorine, bromine and iodine

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25
Q

What are all the types of demonstration observations?

A

chlorine water, bromine water, and iodine solution with chloride ions, bromide ions and iodide ions

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26
Q

what is the demonstration observation between chlorine water and chloride ions?

A

No change

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27
Q

what is the demonstration observation between chlorine water and bromide ions?

A

orange

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28
Q

what is the demonstration observation between chlorine water and iodide ions?

A

brown

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29
Q

what is the demonstration observation between bromine water and chloride ions?

A

Orange

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30
Q

what is the demonstration observation between bromine water and bromide ions?

A

No change

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31
Q

what is the demonstration observation between bromine water and iodide ions?

A

Brown

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32
Q

what is the demonstration observation between iodine solution and chloride ions?

A

Stays brown

33
Q

what is the demonstration observation between iodine solution and bromide ions?

A

Stays brown

34
Q

what is the demonstration observation between iodine solution and iodide ions?

A

No change

35
Q

what happens when organic solvent (such as cyclohexane) is added to aqueous halogens?

A

The molecules are extracted into the organic layer (the top) and a more vivid colour is present

36
Q

in organic solvents like pentane and cyclohexane what colour is iodine?

A

Violet/purple colour

37
Q

what colour is iodine in aqueous solution?

A

brown

38
Q

when with the organic layer of iodine be pale green?

A

if it was added to chlorine water on its own

39
Q

what does chlorine look like when an organic solvent is added to it?

A

-Organic layer (organic solution) is colourless /green
-Aqueous layer (water solution) colourless /green

40
Q

what does bromine look like when an organic solvent is added to it?

A

-organic layer (organic solution) is orange
-Aqueous layer (water solution) is orange

41
Q

what does iodine look like when an organic solvent is added to it?

A

-organic layer (organic solution) is purple
-aqueous layer (water solution) is brown

42
Q

what are organic solvents?

A

hydrocarbon liquids

43
Q

what happens when chlorine is added (bubbled) through a solution of potassium iodide?
(worked example of chlorine with iodide)

A

The aqueous solution becomes brown due to the formation of iodine

44
Q

What is the ionic equation of chlorine with iodide?

A

Cl2 (g) + 2l- (aq)—> 2Cl- (aq) + I2 (aq)

(same for bromine with iodide- replace chlorine)

45
Q

what happens to iodide when it reacts with chlorine?

A

It is oxidised to iodine

46
Q

what happens to chlorine when it reacts with iodide?

A

It is reduced to chloride

47
Q

why is chlorine oxidising agent in the reaction of chlorine with iodide?

A

It allows the iodide to be oxidised, itself is reduced

48
Q

what happens when bromine is added to a solution of potassium iodide?

A

-The iodide ion has been oxidised to iodine (forming a brown solution) bromine is being reduced to bromide

49
Q

what happens when chlorine is added to a solution of potassium bromide?

A

-the aqueous solution becomes orange as bromine is formed

50
Q

what is the reaction between chlorine with bromide show?

A

Chlorine is a better oxidising agent than bromine

51
Q

what does the reactions of bromine and chlorine with iodine show?

A

-Has been oxidised to iodine
-Chlorine and bromine are stronger, oxidising agents than iodine
-Iodine being the weakest oxidising agent could not displace any of the others from the solutions

52
Q

in the displacement reactions, what doesn’t have to be considered?

A

-The metal does not have to be considered as it is a spectator ion
(potassium iodide/bromide)

53
Q

what is the difference between chloride and chlorine?

A

chloride=cl-
chlorine=cl2

54
Q

what happens in the reaction of chlorine with bromide ions?

A

-Pale green solution turns orange
-on addition of organic solvent, solution turns red

55
Q

what happens in the reaction of chlorine and iodide ions?

A

-Pale green solution turns brown
-on addition of organic solvent, solution turns purple

56
Q

what happened in the reaction of bromine with iodide ions?

A

-Orange solution turns brown
-on addition of organic solvent, solution turns purple

57
Q

in the reaction of chlorine with bromide and iodide, why is chlorine the best oxidising agent?

A

It oxidises both bromide and iodide

58
Q

In the reaction of iodide with chlorine and bromine, why is iodide the best reducing agent?

A

It reduces both chlorine and bromine

59
Q

What is the full balanced equation for the reaction of sodium iodide and bromine?

A

2Nacl(aq)+Br2(aq) —>2NaBr(aq)+I2(aq)

60
Q

What is the ionic equation for the reaction of sodium iodide and bromine?

A

2I- (aq) + Br (aq) —> 2Br- (aq) + I2 (aq)

61
Q

What is the are the half equations for the reaction of sodium iodide and bromine?

A

Oxidation: 2I- (aq) —> I2 (aq) + 2e-
Reduction: Br2 (aq) + 2e- —> 2Br- (aq)

62
Q

What is disproportionation?

A

when an element is being both oxidised and reduced in a reaction

63
Q

what happens when chlorine, bromine and iodine are mixed with alkali?

A

They disproportionate

64
Q

what is the equation for the reaction between sodium hydroxide and chlorine (example of disproportionation)? (important)

A
65
Q

what is the condition of the disproportionation reaction of sodium hydroxide and chlorine? (important)

A

-cold dilute alkali

66
Q

what does the disproportionation reaction between sodium and chlorine give?

A

Chloride and chlorate ions, which are present in bleach.

67
Q

What is the ionic equation for the disproportionation of chlorine?

A

Cl2 (g) + 2OH- (aq) —> Cl- (aq) + ClO- (aq) + H2O (l)

68
Q

What do ionic equations balance in terms of?

A

Chemical species and charge

69
Q

what is the reaction of chlorine with water used in?

A

Water Purification

70
Q

what occurs when chlorine reacts with water?

A

Disproportionation reaction occurs

71
Q

what is formed when chlorine reacts with water?

A

Hydrochloric acid and chloric (I) acid performed

72
Q

what does the chlorate ion (OCl-) do?

A

-Kills bacteria as it acts as a weak bleach

73
Q

How can the acidic nature and the bleaching effect of chlorine and water be seen?

A

by adding Blue Litmus indicator into aqueous chlorine

74
Q

what happens to the blue litmus indicator when added into aqueous chlorine?

A

Blue litmus indicator will turn red (due to the acid) then colourless (due to the bleach)

75
Q

Why do some people think we should not put chlorine and drinking water?

A

-chlorine is toxic and excess
-Chlorine to react with hydrocarbons to form chlorinated hydrocarbons with carcinogens

76
Q

what does the V mean in the name of the sodium compound with the systemic name sodium chlorate (V)?

A

The chlorine has an oxidation state of +5

77
Q

what is the overall equation for the reaction of iodine with dilute sodium hydroxide at 25°C?

A

I2 (aq) + 2NaOH- (aq) —> NaIO (aq) + NaI (aq) + H29 (l)

78
Q

what is the ionic equation for the reaction of iodine with dilute sodium hydroxide at 25°C?

A

I2 (aq) + 2OH- (aq) —> IO- (aq) + I- (aq) + H2O (l)