C2.4 - R* Group 7 - the halogens

Question 1

What are the group 7 elements called?

Answer 1

The group 7 elements are called the halogens

Question 2

The group 7 elements

Answer 2

The group 7 elements are:

1. Fluorine
2. Chlorine
3. Bromine
4. Iodine
5. Astatine

Question 3

Halogens

Answer 3

The halogens are a group of toxic non-metals that have:

1. Coloured vapours
2. Fairly typical properties of non-metals

Question 4

What are the fairly typical properties of non-metals?

Answer 4

The fairly typical properties of non-metals:
1. They have low melting points and boiling points
Their melting and boiling points increase going down the group
2. They are poor conductors of heat and electricity

Question 5

As elements, what do the halogens all exist as?

Answer 5

As elements, the halogens all exist as diatomic molecules, made up of pairs of atoms

Question 6

The electronic structure of the halogens determines the way they react with other elements.
How many electrons do they have in their outermost shell (highest energy level)?

Answer 6

The halogens have 7 electrons in their outermost shell (highest energy level)

Question 7

What happens when halogens react with non-metals?

Answer 7

When halogens react with non-metals, they gain an extra electron by sharing a pair of electrons with another atom

Question 8

How fluorine reacts with hydrogen

Answer 8

Fluorine reacts explosively with hydrogen

Question 9

How chlorine reacts with hydrogen

Answer 9

Chlorine reacts explosively with hydrogen, in sunlight

Question 10

How bromine reacts with hydrogen

Answer 10

Bromine reacts with hydrogen, only:

1. At over 300 degrees Celsius
2. In the presence of a platinum catalyst

Question 11

How iodine reacts with hydrogen

Answer 11

Iodine reacts with hydrogen, only:

1. At over 300 degrees Celsius
2. In the presence of a platinum catalyst

Question 12

Examples of halogens reacting with metals, when the halogen atoms gain a single electron to give them a stable arrangement of electrons and form ions with a 1- charge

Answer 12

Examples of halogens reacting with metals, when the halogen atoms gain a single electron to give them a stable arrangement of electrons and form ions with a 1- charge are:

1. Sodium chloride
2. Iron (III) bromide

Question 13

To check the order of reactivity of the halogens, you can do what?

Answer 13

To check the order of reactivity of the halogens, you can carry out test tube reactions

Question 14

What rule do you use when carrying out test tube reactions to check the order of reactivity of the halogens?

Answer 14

The rule you use when carrying out test tube reactions to check the order of reactivity of the halogens is that a more reactive halogen will displace a less reactive halogen from solutions of its salts

Question 15

When carrying test tube reactions to check the order of reactivity of the halogens, you use what?

Answer 15

When carrying test tube reactions to check the order of reactivity of the halogens, you use solutions of:

1. The halogens
2. Their salts in water

Question 16

When carrying out test tube reactions to check the order of reactivity of the halogens, what will the colour of the solution after mixing be due to?

Answer 16

When carrying out test tube reactions to check the order of reactivity of the halogens, the colour of the solution after mixing will be due to the less reactive of the pair of halogens

Question 17

What will chlorine (aq) be in solution?

Answer 17

Chlorine (aq) will be very pale green in solution

Question 18

What will bromine (aq) be in solution?

Answer 18

Bromine (aq) will be yellow in solution

Question 19

What will iodine (aq) be in solution?

Answer 19

Iodine (aq) will be darker red/brown colour

Question 20

Why can you not carry out fluorine reactions in aqueous solutions, even though you know it would displace all of the other halogens as it is the most reactive?

Answer 20

You cannot carry out fluorine reactions in aqueous solutions, even though you know it would displace all of the other halogens as it is the most reactive, because it reacts so violently with water

Question 21

Describe fluorine

Answer 21

Fluorine is a very reactive, poisonous yellow gas

Question 22

Describe chlorine

Answer 22

Chlorine is a fairly reactive, poisonous, dense green gas

Question 23

Describe bromine

Answer 23

Bromine is a poisonous, dense red-brown volatile liquid

Question 24

Describe iodine

Answer 24

Iodine is a:
1. Dark grey crystalline solid
Or,
2. Purple vapour

Question 25

As elements, the halogens all exist as molecules made up of pairs of atoms - diatomic molecules. How are the atoms in each pair joined to each other?

Answer 25

The atoms in each pair are joined to each other by a covalent bond

Question 26

When carrying test tube reactions to check the order of reactivity of the halogens, you use solutions of the halogens and their salts in water. Example

Answer 26

For example, chlorine dissolved in water, mixed with potassium bromide solution

Question 27

The trends as you go down group 7

Answer 27

The trends as you go down group 7 are: 1. Reactivity decreases 2. Melting and boiling points increase 3. Relative atomic masses increase

Question 28

How do all the group 7 elements react?

Answer 28

All the group 7 elements react in similar ways

Question 29

Why do all the group 7 elements react in similar ways?

Answer 29

All the group 7 elements react in similar ways, because they all have 7 electrons in their outer shell

Question 30

What can halogen atoms do, to achieve a full outer shell?

Answer 30

Halogen atoms can share electrons to achieve a full outer shell

Question 31

Halogen atoms can share electrons, via covalent bonding with other non-metals, to achieve a full outer shell. Example

Answer 31

``` For example: 1. HCl 2. HF 3. CCl4 contain covalent bonds ```

Question 32

What do the compounds that form when halogens react with non-metals all have?

Answer 32

The compounds that form when halogens react with non-metals all have simple molecular structures

Question 33

What do the compounds that form when halogens react with metals all have?

Answer 33

The compounds that form when halogens react with metals all have ionic structures

Question 34

What can a displacement reaction occur between?

Answer 34

A displacement reaction can occur between: 1. A more reactive halogen 2. The salt of a less reactive one

Question 35

The electronic structure of the halogens determines the way they react with other elements. The halogens have 7 electrons in their outermost shell (highest energy level), so they need to gain just one more electron to achieve what?

Answer 35

The halogens have 7 electrons in their outermost shell (highest energy level), so they need to gain just one more electron to achieve the stable electronic structure of a noble gas

Question 36

When halogens react with non-metals, they gain an extra electron by sharing a pair of electrons with another atom. Examples

Answer 36

For example: 1. Hydrogen 2. Oxygen

Question 37

Fluorine reacts explosively with hydrogen, even what?

Answer 37

Fluorine reacts explosively with hydrogen, even: 1. At -200 degrees Celsius 2. In the dark

Question 38

Chlorine reacts explosively with hydrogen, in sunlight, but how in the dark?

Answer 38

Chlorine reacts explosively with hydrogen, in sunlight, but slowly in the dark

Question 39

Iodine reacts with hydrogen, only at over 300 degrees Celsius and in the presence of a platinum catalyst. It is what?

Answer 39

The reaction of iodine and hydrogen, at over 300 degrees and in the presence of a platinum catalyst is: 1. Very slow 2. Reversible

Question 40

Examples of halogens reacting with metals, when the halogen atoms gain a single electron to give them a stable arrangement of electrons and form ions with a 1- charge are Sodium chloride and iron (III) bromide. These are what compounds?

Answer 40

1. Sodium chloride 2. Iron (III) bromide are ionic compounds

Question 41

When carrying out test tube reactions to check the order of reactivity of the halogens, the colour of the solution after mixing will be due to the less reactive of the pair of halogens, which is what?

Answer 41

When carrying out test tube reactions to check the order of reactivity of the halogens, the colour of the solution after mixing will be due to the less reactive of the pair of halogens, which is left in solution as the aqueous molecule

Question 42

Halogen atoms can share electrons, via what, to achieve a full outer shell?

Answer 42

Halogen atoms can share electrons, via covalent bonding with other non-metals, to achieve a full outer shell