2(b) - Group 7

Question 1

What are the group 7 elements called?

Answer 1

halogens

Question 2

What is the colour and physical state of chlorine at room temperature?

Answer 2

colour: green
state: gas

Question 3

What is the colour and physical state of bromine at room temperature?

Answer 3

colour: red-brown
state: liquid

Question 4

What is the colour and physical state of iodine at room temperature?

Answer 4

colour: grey
state: black/ dark purple

Question 5

Use knowledge of trends in Group 7 to predict the properties of fluorine and astitane:

Answer 5

Fluorine:

colour: Yellow
state: Gas

Astatine:

colour: Black
state: Solid

Question 6

How is the reactivity ordered in group 7?

Answer 6

Group 7 elements are called the Halogens. As you go up group 7 (decreasing atomic number), the elements become more reactive. For example, fluorine is the most reactive and astatine is the least reactive.

Question 7

What is a displacement reaction?

Answer 7

When a more reactive element replaces a less reactive element in a compound.

Question 8

What is a halide?

Answer 8

A halide ion is a halogen atom bearing a negative charge.

Question 9

By reacting a halogen solution with a potassium halide solution and making observations, the order of their reactivity can be deduced, how is this and what is the equation for chlorine reacting with bromine?

Answer 9

A more reactive halogen will displace a less reactive halogen, e.g. chlorine will displace bromine:

Cl2(aq) + 2KBr(aq) –> 2KCl(aq) + Br2(aq)

Question 10

What displacement reactions will happen the 3 elements in group 7?

Answer 10

• chlorine displaces both bromine and iodine and bromine displaces iodine. Therefore the order of reactivity is: chlorine is more reactive than bromine, which in turn is more reactive than iodine.