Halogens

Question 1

What group is called the halogens

Answer 1

Group 7

Question 2

Give the name of Group 7

Answer 2

Halogens

Question 3

Give the formula for each halogen

Answer 3

Fluorine - F2
Chlorine - Cl2
Bromine - Br2
Iodine - I2 (subscript 2)

Question 4

What type of structure are the halogens

Answer 4

Halogens are molecular in structure

Question 5

State some physical properties of the Group 7 elements

Answer 5

low density
brittle
thermal insulator
electrical insulator
dull

Question 6

What does aqueous mean

Answer 6

Aqueous means dissolved in water

Question 7

What are group 7 ions called

Answer 7

Group 7 ions are called halide ions

Question 8

Finish the sentence:
A more reactive halogen will displace a less reactive halide ion from it’s _________ compound

Answer 8

A more reactive halogen will displace a less reactive halide ion from it’s ionic compound

Question 9

What colour are halide ion compounds

Answer 9

Halide ion compounds are colourless
e.g. potassium chloride

Question 9

What colour are halide ion compounds

Answer 9

Halide ion compounds are colourless
e.g. potassium chloride

Question 10

State the properties of Fluorine

Answer 10

Fluorine is a pale, yellow gas, poisonous and highly reactive

Question 11

State the properties of Chlorine

Answer 11

Chlorine is denser than fluorine
Chlorine is a dense green gas
It is very reactive (but less reactive than fluorine)
Poisonous

Question 12

State the properties of Bromine

Answer 12

Bromine is a dense, poisonous, orange-brown volatile liquid
Volatile- it can change state easily
Bromine easily turns into a vapour

Question 13

State the properties of Iodine

Answer 13

Iodine is a dark grey solid. Iodine sublimes to a purple vapour upon heating

Subliming - when a solid turns into a vapour or vice versa

Question 14

All halogens form ___ vapours

Answer 14

All halogens form coloured vapours

Question 15

Describe and explain halogens in terms of melting points and boiling points

Answer 15

Halogens have low melting points and boiling points as the forces between the molecules are very weak.

Question 16

In their elemental form, what are halogens

Answer 16

In their elemental form, all halogens are diatomic

Question 17

Describe the trend in melting points in group 7

Answer 17

In group 7 Their melting points increase, down the group

Question 18

Describe the trend in boiling points in group 7

Answer 18

In Group 7, their boiling points increase, down the group

Question 19

Describe the trend in reactivity in Group 7

Answer 19

In Group 7, their reactivity decreases, down the group

Question 20

What are diatomic molecules

Answer 20

Diatomic molecules are two atoms that are covalently bonded together

Question 21

Explain the trend in melting point and boiling point in Group 7

Answer 21

The melting points and boiling points increase down the group, because as going down Group 7 the molecules become larger, the intermolecular forces become stronger, meaning more energy is need to overcome these forces.

Question 22

In terms of electrons, what happens to Group 7 atoms when they react with metals
What type of compound is formed

Answer 22

When Group 7 atoms react with metals, they gain an extra electron, from the metal to form 1- ions
An ionic compound is formed

Question 23

In terms of electrons, what happens to Group 7 atoms when they react with non-metals
What type of compound is formed

Answer 23

Group 7 atoms share their electrons with another atom
A covalent/simple molecular/molecular compound is formed

Question 24

What colour is bromine water Br2 (aq) - (bromine dissolved in water

Answer 24

Bromine water is orange/yellow

Question 25

What colour is chlorine water Cl2 (aq) - (chlorine dissolved in water

Answer 25

Chlorine water is pale green

Question 26

What colour is iodine water I2 (aq) - (iodine dissolved in water

Answer 26

Iodine water is brown

Question 27

State the products and an observation from the following reaction
Potassium bromide + chlorine

Answer 27

Potassium bromide + chlorine —> potassium chloride + bromine
An orange/yellow solution forms - this is the colour of the displaced bromine dissolved in water

Question 28

State the products and an observation from the following reaction
Potassium iodide + chlorine

Answer 28

Potassium iodide + chlorine ——> potassium chloride + iodine
A brown solution forms - this is the colour of the displaced iodine dissolved in water

Question 29

Explain the trend in reactivity of Group 7

Answer 29

Going down the group, the atoms become larger
The distance between the nucleus and the outer electron is greater, meaning it has more electron shells.
This results in increased shielding, which means the electrostatic attraction between the nucleus and the outer electron is weaker
Therefore, it is harder to attract and gain an extra incoming electron

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32
Q
Why is sodium more reactive than lithium

A
A sodium atom is larger than a lithium atom

This means that the distance between sodium’s nucleus and it’s outer electron is greater than the distance between lithium’s nucleus and outer electron, which means that sodium has more electron shells than lithium.

This results in more shielding being experienced by sodium than lithium , which means that the electrostatic attraction between sodium’s nucleus and outer electron is weaker than the attraction between lithium’s nucleus and outer electron,

Therefore, sodium’s outer electron is lost more easily

Question 30

Why is fluorine more reactive than bromine

Answer 30

Both Fluorine and Bromine atoms need to gain an electron to achieve a full outer shell

Due to the fact Fluorine is smaller than Bromine, the distance between Fluorine’s nucleus and it’s outer electron is less than the distance between bromines nucleus and outer electron, which means that fluorine has less electron shells than lithium.

This results in less shielding being experienced by fluorine than bromine, which means that the electrostatic attraction between fluorine’s nucleus and outer electron is stronger than the attraction between bromine’s nucleus and outer electron,

Therefore, fluorine gains an electron easier than bromine so it is more reactive

Question 31

Draw a fluorine atom