group 2 and 7

Question 1

What is a common name given to group 2 metals

Answer 1

Alkaline earth metals

Question 2

What is the most reactive metal of group 2

Answer 2

Barium

Question 3

List 3 physical properties of group 2 metals

Answer 3

• High melting and boiling points
• Low-density metals
• Form colourless (white) compounds

Question 4

What ions does group 2 form in redox reactions?

Answer 4

Group 2 lose their two outer electrons to form 2+ ions

Question 5

The highest energy electrons of group 2 metals are in which subshell?

Answer 5

S-subshell

Question 6

What are the relative reactivities of Group 2 elements in redox reactions with oxygen

Answer 6

When group 2 metals are burnt in oxygen, they form solid white oxides.

Question 7

What are the relative reactivities of Group 2 elements in redox reactions with water

Answer 7

The group 2 metals react with water to give metal hydroxide and a hydrogen gas

Question 8

What are the relative reactivities of Group 2 elements in redox reactions with dilute acids

Answer 8

When group 2 metals react with dilute hydrochloric acid, you get a metal chloride and hydrogen gas

Question 9

What is the trend of reactivity down group 2 metals

Answer 9

• Reactivity increases

- Electrons are lost more easily because larger atomic radius and more shielding

Question 10

What is the trend in first ionisation energy down group 2

Answer 10

• Decreases
• Because electron number increases so shielding increases
• Increases atomic radius so there are weaker nuclear forces
• So less energy is needed to remove the electron

Question 11

Which group 2 element reacts very slowly with water?

Answer 11

Magnesium

Question 12

What type of reaction is the reaction between group 2 elements and oxygen?

Answer 12

Redox reaction

Question 13

What type of reaction is the reaction between group 2 metals and water?

Answer 13

Redox reaction

Question 14

What is oxidised and what is reduced in a reaction between group 2 metal and water?

Answer 14

• Metal is oxidised

- One hydrogen atom from each water is reduced

Question 15

What group 2 metal oxide is insoluble in water?

Answer 15

Beryllium oxide

Question 16

What is the trend in hydroxide solubility down group 2?

Answer 16

• Increases down the group

Question 17

What is the use of Ca(OH)2

Answer 17

Used to neutralise soil

Question 18

What is the use of Mg(OH)2

Answer 18

• Antacid to treat indigestion

Question 19

What is calcium carbonate used for

Answer 19

• Present in limestone and marble

- Used in building construction

Question 20

List 2 properties of halogens

Answer 20

1. Low melting and boiling point

2. Exist as diatomic molecules

Question 21

Explain the trend in the boiling group down group 7

Answer 21

• Increases down the group
• Because size of the atom increases as more occupied shells
• Stronger London forces of attraction between molecules, take more energy to overcome

Question 22

Explain the trend in reactivity down group 7

Answer 22

• Reactivity decreases
• Because atomic radius increases
• Electron shielding increases
• Ability to gain an electron and form -1 ions decreases

Question 23

Explain the trend in oxidising ability down the group

Answer 23

• Decreases down the group
• Cl has the fewest occupied electron shells, and greatest nuclear attraction so it is easiest to gain electrons and be reduced

Question 24

Explain the trend in reducing the ability of the halides down the group

Answer 24

• Increases down the group
• Iodine has the most occupied electron shells so outer electrons are further from the nucleus, and is the easiest to be oxidised and lose electrons

Question 25

What is the colour of chlorine in water

Answer 25

Pale green

Question 26

What is the colour of bromine in water

Answer 26

Orange

Question 27

What is the colour of iodine in water

Answer 27

Brown

Question 28

What is the colour of chlorine in cyclohexane

Answer 28

Pale green

Question 29

What is the colour of bromine in cyclohexane

Answer 29

Orange

Question 30

What is the colour of iodine in cyclohexane

Answer 30

Violet

Question 31

Define disproportionation

Answer 31

When an element is oxidised and reduced at the same time in a redox reaction

Question 32

What type of reaction is the reaction of chlorine with water

Answer 32

Disproportionation

Question 33

Why is chlorine added to drinking water

Answer 33

It kills the bacteria in the water and makes it safer to drink

Question 34

What is the equation for forming bleach?

Answer 34

Cl2 + 2NAOH -> NaCl + NaClO + H2O

Question 35

What is the formula of bleach

Answer 35

NaClO

Question 36

What kind of molecules do halogens exist as?

Answer 36

Diatomic molecules

Question 37

How can you see the colour change in a displacement reaction with halogens?

Answer 37

By adding an organic solvent like hexane, it settles out a distinct layer above the aqueous solution

Question 38

Describe the test for halides

Answer 38

1. Add dilute nitric acid 2. Add silver nitrate solution 3. A precipitate of the silver halide is formed 4. Test results by adding ammonia solution

Question 39

What is observed in the silver test for halides if a chloride ion is present?

Answer 39

- Precipitate colour: white | - Solubility in ammonia: dissolved in dilute NH3

Question 40

What is observed in the silver test for halides if a bromide ion is present?

Answer 40

- Precipitate colour: Cream | - Solubility in ammonia: dissolves in concentration

Question 41

What is observed in the silver test for halides if an iodide ion is present?

Answer 41

- Precipitate colour: Yellow | - Solubility in ammonia: insoluble in concentration

Question 42

What are the alternatives to using chlorine in water and explain them?

Answer 42

1. Ozone - A strong oxidising agent which makes it good for killing microorganisms, its expensive to produce and has a short-half life so it's treatment isn't permanent 2. Ultraviolet light - It kills microorganisms by damaging their DNA, it is ineffective in cloudy water and it won't stop the water from being contaminated further down