Group 7 Flashcards

1
Q

What sort of molecules do Halogens exist in as an element?

A

Diatomic Molecules.

Two covalently bonded.

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2
Q

What are the physical properties of Halogens?

A
  • Low melting and boiling points

- Exist as diatomic molecules

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3
Q

What is the trend in Boiling point in the Halogens?

A

As you move down the group the Boiling point increases.

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4
Q

What causes the trend in the Halogen’s boiling points?

A

As you go down it increases as there are more electrons. There are more Van Der Waals forces.

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5
Q

What is an Oxidising Agent?

A

An element that oxidises other elements in a redox reaction.

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6
Q

What happens to Halogens in terms of electrons in a Redox reaction?

A

They gain an electron to form a halide ion with a negative one charge.

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7
Q

What is the trend in oxidising power for the Halogens?

A

As you head down they become less strong oxidising agents.

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8
Q

What is the trend in Reactivity for Halogens?

A

As you head down they become less reactive.

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9
Q

What causes the trend in Reactivity/Oxidising power for the Halogens?

A
  • The atomic Radius Increases
  • The electron shielding increases
  • This cancels out a higher atomic charge
  • So the ability to gain an electron decreases
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10
Q

What tests can be done to show the Reactivity of the halogens?

A

Displacement between Halide Ions and the Halogens in Aqueous solution .

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11
Q

What organic solvent can be used to show a displacement reaction has taken place?

A

Cyclohexane.

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12
Q

What colour is Cl2 in Water?

A

Pale-green

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13
Q

What colour is Br2 in Water?

A

Orange

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14
Q

What colour is I2 in Water?

A

Brown

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15
Q

What colour is Cl2 in Cyclohexane?

A

Pale-green

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16
Q

What colour is Br2 in Cyclohexane?

A

Orange

17
Q

What colour is I2 in Cyclohexane?

A

Violet

18
Q

In a displacement reaction what happens to the stronger oxidising agent?

A

It forms ions. It becomes part of the compound.

19
Q

Define a Displacement reaction.

A

A displacement reaction is a reaction where a more-reactive/stronger oxidising agent displaces a less-reactive/ weaker oxidising agent from an aqueous solution of the latters ions.

20
Q

Define a disproportionation reaction.

A

Where an element is both Oxidised and Reduced in a redox reaction.

21
Q

What is a reaction where the same element is both Oxidised and Reduced?

A

Disproportionation.

22
Q

Why is Chlorine added to water?

A

Because it kills bacteria.

23
Q

What is the danger of adding Chlorine to water?

A

It can form toxic chlorinated hydrocarbons.

24
Q

What are the products of Chlorine and Water?

A

Two acids:

  • HCl-Hydrochloric Acid
  • HClO-Chloric (I) Acid
25
Q

What are the products of Chlorine and Aqueous NaOH?

A
  • NaCl
  • NaClO
  • H20
26
Q

What is the formula for Bleach?

A

NaClO

27
Q

How do you test for Halide ions?

A

Precipitation tests. Dissolving in water and adding Silver Nitrate.

28
Q

What is the formula for Silver Nitrate?

A

AgNO3

29
Q

What is a Silver Ion?

A

Ag 1+

30
Q

When a Halide and Silver Nitrate react what happens?

A

A coloured silver halide precipitate is formed.

31
Q

If the colour of a Silver halide precipitate isn’t clear, what can be added?

A

Aqueous Ammonia.

NH3

32
Q

What colour is the precipitate of a Chloride?

A

White

33
Q

What colour is the precipitate of a Bromide?

A

Cream

34
Q

What colour is the precipitate of Iodide?

A

Yellow

35
Q

Is a chloride precipitate soluble in Ammonia?

A

Yes. In dilute.

36
Q

Is a bromide precipitate soluble in Ammonia?

A

Not in dilute but in Concentrated yes.

37
Q

Is an Iodide precipitate soluble in Ammonia?

A

No it isn’t soluble in any ammonia.

38
Q

Define a Precipitation reaction.

A

When a solid is formed in a chemical reaction between two aqueous solutions.