4.3 Halogens

Question 1

What is a halogen?

Answer 1

Group 7 elements that are covalently bonded (simple molecular)

Question 2

Trend in properties of group 7

Answer 2

• All diatomic
• Colour gets darker down the group
• MP/BP increases down the group

Question 3

Colour and state of fluorine

Answer 3

F2, Very Pale Yellow, gas

Question 4

Colour and state of Chlorine

Answer 4

Cl2, Pale Green, Gas

Question 5

Colour and state of Bromine

Answer 5

Br2, Brown, Liquid, volatile and releases brown fumes

Question 6

Colour and state of Iodine

Answer 6

I2, Dark Grey, Solid, when it sublimes releases purple fumes

Question 7

Colour and state of Astatine

Answer 7

At2, Black, Solid

Question 8

Reaction of Halogens and Metals

Answer 8

Form ionic compounds

Question 9

Example of Halogen + Metal

Answer 9

Sodium + Chlorine —> Sodium Chloride (2Na + Cl2 —> 2NaCl)

Question 10

Why is a Reaction Between a Halogen and Metal Redox?

Answer 10

Na loses electrons (oxidised)

Cl gains electrons (reduced)

Question 11

What does Cl change its name to?

Answer 11

From Chlorine Atom, To Chloride Ion

Question 12

Reactivity Trend Halogens

Answer 12

• Less reactive as you go down group 7
• Need to gain 1 electron & more shells as you go down
• Meaning the outer shell is further away from nucleus (weaker attraction)
• Attraction to nucleus is weaker

Question 13

Test for Chlorine

Answer 13

Damp blue litmus paper, turns white if chlorine is present (chlorine acts as bleaching agent)

Question 14

Hydrogen Chloride Properties

Answer 14

• Simple molecular
• Gas (low MP/BP)
• Colourless
• When made from Hydrogen and Chloride, colour change from Green to Colourless