C4.1.2

Question 1

What non-metal properties do the group 7 elements have?

Answer 1

• being brittle in the solid state
• poor conductors of energy

Question 2

What are all the Group 7 elements? (D____mic, ____ intermolecular forces, states at room temperature)

Answer 2

• they are all diatomic
• they have weak intermolecular forces
• different states at room temperature

Question 3

What colours are they/ coloured vapours do they form?

Answer 3

Fluorine - pale yellow gas
Chlorine - green gas
Bromine - orange-brown liquid that vapourises easily
Iodine - shiny grey-black crystalline solid that sublimes* to form a purple vapour
*sublimes - (of a solid substance) change directly into vapour when heated, typically forming a solid deposit again on cooling

Question 4

What is the trend when you go down the group?

Answer 4

• density increases
• melting and boiling points increase

Question 5

Why are the Group 7 metals called halogens? For eg. Sodium and chlorine

Answer 5

• they react with metals to produce salts
• they react vigorously with the Group 1 metals, especially if the metal is heated first
  For eg, 2Na(l) + Cl2(g) —> 2NaCl(s)

Question 6

What happens to the reactivity as you go down the group? Why?

Answer 6

• reactivity decreases, opposite to the alkali metals
• more shielding as you go down the group
• the atomic size increases, so the attraction between the electrons and nucleus decreases
• it is harder to gain an electron, meaning the reactivity decreases

X2 + 2e- —> 2X-