Halogens

Question 1

Trend in melting point and boiling point

Answer 1

Increases down the group as the molecules become larger and have more electrons. Therefore the van der Waals forces between the molecules increase so more energy is needed to break the forces

Question 2

Trend In electronegativity

Answer 2

Decreases down the group as the atomic radii increases due to the increasing number of shells and therefore the nucleus is less able to attract the bonding pair of electrons

Question 3

Oxidising strength down the group

Answer 3

Decreases

Question 4

Fluorine

Answer 4

Pale yellow gas that is highly reactive

Question 5

Chlorine

Answer 5

Greenish,reactive gas, poisonous in high concentrations

Question 6

Bromine

Answer 6

Red liquid , that gives off brown/orange poisonous fumes

Question 7

Iodine

Answer 7

Shiny grey solid sublimes to purple gas

Question 8

What test is used to identify the presence of a halide ion?

Answer 8

Reaction with silver nitrate

Question 9

What does Fluorides and silver nitrate produces?

Answer 9

No precipitate

Question 10

What does Chlorides and silver nitrate produce?.

Answer 10

A white precipitate

Question 11

What does Bromides and silver nitrate produce?

Answer 11

A cream precipitate

Question 12

What does iodide and silver nitrate produce ?

Answer 12

A pale yellow precipitate

Question 13

What can the silver halide precipitate be treated with if the colours are similar ?

Answer 13

Ammonia solution

Question 14

Reducing power of halide ions down the group

Answer 14

Increases as the ions get bigger, it is easier for the outer electrons to be given away

Question 15

What is disproportion?

Answer 15

Is the name given where an element simultaneously oxidises and reduces.

Question 16

Equation for the reaction of chlorine with water

Answer 16

Cl2(g)+H2O(l)—> HClO(aq)+HCl

Question 17

The reaction of chlorine with water in the presence of bright sunlight

Answer 17

2Cl2+2H2O—>4H+ +4Cl- +O2

Question 18

What is chlorine used for?

Answer 18

• used in water treatment to kill bacteria

- used to treat drinking water and water in swimming pools

Question 19

What type of reaction is chlorine with water

Answer 19

Disproportionate

Question 20

Test for the presence of chlorine

Answer 20

Blue litmus turns red in the presence of chlorine (bleaches it)

Question 21

What is the oxidation state of halogens?

Answer 21

-1

Question 22

What is electronegativity?

Answer 22

It is the ability of an atom to attract electrons in a covalent bond.