ES1 - Halogens

Question 1

What is the colour and physical state of the first 4 halogens? Also describe the colour of iodine as a gas

Answer 1

Fluorine: pale yellow gas
Chlorine: pale green gas
Bromine: red liquid
Iodine: grey solid 
Iodine is purple as a gas

Question 2

What is the solubility of halogens like in water? Explain why

Answer 2

Halogens are not very soluble with water at all because halogens are non-polar molecules and water is a polar molecule so they separate and do not interact (but can react with water)

Question 3

What is the solubility of halogens like in organic solvents?

Answer 3

Halogens are very soluble in organic solvents as both organic solvents and halogens are non-polar

Question 4

What is the trend in reactivity amongst the halogens? Explain why in terms of electronegativity

Answer 4

Gets less reactive down the group

Electronegativity decreases and the intermolecular forces become weaker as the atoms get bigger down the group - outer electrons are further away from the nucleus and it becomes more difficult to gain electrons as the forces are weaker. This means that reactivity decreases down the group as it is more difficult to attract electrons when the nucleus is so far away from the outer electrons

Question 5

Are halogens usually reduced or oxidised? How are they useful in this way?

Answer 5

Halogens tend to get reduced to 1- ions

They are good oxidising agents (fluorine being best)

Question 6

Does the boiling point increase or decrease going down group 7?

Answer 6

Boiling point for halogens increases going down the group

Question 7

What is the trend in volatility with halogens?

Answer 7

They become less volatile down the group

Question 8

What colour is chlorine, bromine and iodine when dissolved in water?

Answer 8

Chlorine: pale green
Bromine: orange/yellow
Iodine: brown

Question 9

What colour is chlorine, bromine and iodine dissolved in cyclohexane?

Answer 9

Chlorine: pale green
Bromine: orange/brown/red
Iodine: violet