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Flashcards in Group 7 Deck (17)
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1
Q

What are the 1st 5 halogens their colour and state and RTP?

A
Fluorine- yellow/pale green gas
Chlorine- pale green gas
Bromine- orange liquid
Iodine- black solid
Astatine- black solid
2
Q

What is the trend of boiling point down the group?

A

Increases down a group as the London forces strength increases due to more electrons.

3
Q

What is the trend of reactivity down the group and why?

A

Decrease in reactivity as there is more shielding and decreasing attraction due to a larger atomic radii, making it harder to attract the electron

4
Q

What is the trend in strength of oxidising agent as you go down the group?

A

Decreases

5
Q

What are the properties of a halogen?

A
Low melting and boiling points
Diatomic molecules which are:
Non polar (as same element)
And have Weak London forces between the molecules
6
Q

What compounds do they form and what colour are they?

A

Ionic compounds

White solids

7
Q

What is a group 7 redox half equation?

A

X2 + 2e- -> 2X-

8
Q

How does a halogens oxidation number change in a redox reaction and what does this suggest?

A

X(0) -> X(-1)

Means they are reduced and acts as the oxidising agent

9
Q

Which is the strongest halogen and why?

A

Fluorine as it forms the negative F- ion the easiest

10
Q

What is a displacement reaction?

A

The more reactive halogen will displace the less reactive halogen, it will oxidise the halide ion of a less reactive halogen.

11
Q

What are the colours of the halogens in:

  1. Water
  2. Cyclohexane
A

Fluorine:

  1. Yellow/green
  2. Colourless

Chlorine:

  1. Pale green
  2. Pale green

Bromine:

  1. Orange
  2. Orange

Iodine:

  1. Brown
  2. Violet
12
Q

Why may chlorine be dangerous?

A
  1. Toxic gas
  2. Environmentalists suspect when in water it reacts with organic matter forming chlorinated hydrocarbons which may cause cancer
13
Q

Why can chlorine be useful?

A

When dissolved in water it is a powerful disinfectant so makes the water safe to drink which will improve public health by reducing water borne diseases like cholera.

14
Q

What is disproportionation?

A

A redox reaction where the same element is simultaneously oxidised and reduced

15
Q

What is the reaction equation of the disproportionation of chlorine with water?
And what are the oxidation numbers?

A

Cl2 + H2O HCl + HClO

Cl(0) -> Cl(+1) oxidised (HClO)
Cl(0) -> Cl(-1) reduced (HCl)

16
Q

What does a ClO- ion do?

A

Bleaches- removes colour, whitens or disinfects often by oxidation

17
Q

What is the reaction equation of the disproportionation reaction of chlorine with cold dilute NaOH (aq)?
What are the oxidation numbers?

A

Cl2 + 2NaOH -> NaCl + NaClO + H2O

Cl(0) -> Cl(-1) reduced in NaCl
Cl(0) -> Cl(+1) oxidised in NaClO