Atomic Structure and the Periodic Table: Group 7

Question 1

How many electrons are on the outer shell of group 7 elements?

Answer 1

7

Question 2

In what form group 7 elements tend to be in?

Answer 2

diatomic molecules - they are in pairs eg Cl₂, I₂

Question 3

What do fluorine, chloride, bromine and iodine all have in common.

Answer 3

They can all form toxic/poisonous gases.

Question 4

How does the melting and boiling point of group 7 elements change as you go down the group on the periodic table?

Answer 4

Their melting and boiling points increase as you go down group 7

Question 5

How does the reactivity of group 7 elements change as you go down group 7?

Answer 5

Their reactivity decreases as you go down group 7

Question 6

Describe 4 group 7 elements and their states of matter.

Answer 6

• fluorine - pale yellow gas
• chlorine - pale green gas
• bromine - dark brown liquid
• iodine - grey solid, can form poisonous purple vapour

Question 7

What will happen when chlorine reacts with sodium bromide? Describe the colour change.

Answer 7

Cl₂ + 2NaBr → Br₂ + 2NaCl
The orange colour of Br₂ would appear.

Question 8

What will happen when chlorine reacts with sodium iodide?

Answer 8

Cl₂ + 2NaI → I₂ + 2NaCl
The brown colour of I₂ would appear

Question 9

What will happen when bromine reacts with sodium iodide? Describe the colour change.

Answer 9

Br₂ + 2NaI → I₂ + 2NaBr
A brown colour of I₂ would appear

Question 10

Why does the reactivity of halogens decrease as you go down group 7?

Answer 10

• the atoms get larger
• so an extra electron will be attracted to the nucleus of the atom more weakly

Question 11

Why does the melting and boiling point of group 7 elements increase as you go down the group?

Answer 11

They are larger molecules as you go down the group