Group 2

Question 1

Describe the trend for atomic radius down group 2.

Answer 1

Increases down group 2. They have more shells of electrons as you go down so the atom is bigger.
Increased inner shielding. Less electrostatic attraction between +ve nucleus and -ve outer electrons.

Question 2

Describe the trend for melting point down group 2.

Answer 2

Decreases down group 2. Metallic bonding weakens as atomic size increases. More inner shielding. Distance between positive ions and delocalised electrons increases. Therefore the electrostatic attraction between the +ve ions and delocalised electrons weakens.

Question 3

Describe the trend for reactivity down group 2.

Answer 3

Increases. More shells and inner shielding causes atomic radii to increase. Less electrostatic attraction between +ve nucleus and -ve outer electrons. Easier to lose electrons to become an ion (must react to become an ion)

Question 4

Describe the trend for first ionisation energy down group 2.

Answer 4

Decreases. More electron shells as you go down the group. Atomic radius increases. More inner shielding. Less electrostatic attraction between +ve nucleus and -ve outer electrons.

Question 5

Explain why the second ionisation energy of calcium is lower than the
second ionisation energy of potassium.

Answer 5

In Ca outer electrons are further from the nucleus and there is more shielding in Ca.

Question 6

Explain, in terms of structure and bonding, why magnesium chloride has a
high melting point.

Answer 6

Giant ionic lattice. Strong electrostatic forces of attraction between oppositely charged ions.

Question 7

Describe the bonding in magnesium.

Answer 7

Attraction between Mg2+ ions and delocalised electrons.

Question 8

Explain why the melting point of magnesium is higher than the melting point of sodium.

Answer 8

Mg has more delocalised electrons than Na.
Stronger metallic bonding in magnesium.

Question 9

Give the reaction for Mg with Oxygen.

Answer 9

Mg + 1/2O2 -> MgO

Question 10

What is seen when Mg burns in oxygen?

Answer 10

A bright white flame.

Question 11

How does MgO appear as?

Answer 11

A white powder.

Question 12

Why does MgO have a high melting point?

Answer 12

Ionic bonding

Question 13

Without a flame, what happens to the reaction between Mg and O2?

Answer 13

Slow

Question 14

What does magnesium ribbon have and how is it formed?

Answer 14

A thin layer of MgO. It is formed by the reaction with oxygen in the air.

Question 15

Before doing reactions with magnesium ribbon, what must happen to the magnesium oxide?

Answer 15

It must be removed by emery paper.

Question 16

What would an uncleaned magnesium ribbon do to the reaction of Mg with an acid?

Answer 16

It would give a false result because both the Mg and MgO would react but at different rates.

Question 17

Give the reaction for Mg and HCl

Answer 17

Mg + 2HCl -> MgCl2 + H2

Question 18

Give the reaction for MgO and HCl

Answer 18

MgO + 2HCl -> MgCl2 + H2O

Question 19

Give the reaction for Mg and steam.

Answer 19

Mg (s) + H2O (g) -> MgO (s) + H2 (g)

Question 20

What would the Mg burn with in the reaction with steam?

Answer 20

A bright white flame.

Question 21

Give the reaction for Mg and warm water.

Answer 21

Mg + 2H2O -> Mg(OH)2 + H2

Question 22

What are the two differences between the reaction of Mg with warm water and Mg with steam.

Answer 22

Warm water is slower.
Warm water has no flame.

Question 23

What do the other group 2 metals react with to form metal hydroxides?

Answer 23

Cold water

Question 24

Give the reaction of Ca with cold water.

Answer 24

Ca (s) + 2H2O (l) -> Ca(OH)2 (aq) + H2 (g)

Question 25

What do the metal hydroxides produced make the water?

Answer 25

More alkaline

Question 26

What could you observe from the reactions of the group 2 metals and water?

Answer 26

Fizzing (more vigorous down group) Metal dissolving (faster down group) Solution heating up (more down group)

Question 27

In the reaction of calcium and cold water, what appears and how about the rest of group 2?

Answer 27

A white precipitate but less precipitate forms down the group.

Question 28

What is used to extract titanium?

Answer 28

Magnesium

Question 29

Why is titanium useful?

Answer 29

It is abundant It is corrosion resistant It has a low density

Question 30

What is titanium used for?

Answer 30

Making strong, light alloys for use in aircraft.

Question 31

Why can't carbon be used to extract titanium?

Answer 31

Titanium carbide (TiC) is formed rather than Titanium. Titanium can't be extracted by electrolysis as it has to be very pure.

Question 32

What is the first equation for extracting titanium?

Answer 32

TiO2 + 2Cl2 + 2C -> TiCl4 + 2CO

Question 33

What is the second equation for extracting titanium?

Answer 33

TiCl4 + 2Mg -> Ti + 2MgCl2

Question 34

What are the 3 steps for extracting titanium?

Answer 34

1)TiO2 (s) is converted into TiCl4 (l) at 900 degrees celsius. 2)TiCl4 is purified by fractional distillation in an argon atmosphere. 3)Ti is extracted by Mg in an argon atmosphere at 500 degrees celsius.

Question 35

Give 2 reasons why titanium is expensive.

Answer 35

Magnesium is expensive High temperatures are required in both steps.

Question 36

Equation for removing SO2?

Answer 36

CaO + SO2 -> CaSO3

Question 37

What are spectator ions?

Answer 37

Ions that don't change state or oxidation number.

Question 38

Describe the solubility of group 2 hydroxides down the group.

Answer 38

Increases down group 2.

Question 39

When group 2 hydroxides are not soluble, what do they appear as?

Answer 39

White precipitates.

Question 40

Is magnesium hydroxide soluble in water?

Answer 40

No

Question 41

Give 3 uses of magnesium hydroxide in medicine?

Answer 41

Neutralises excess stomach acid Indigestion relief Laxative

Question 42

Give the equation of magnesium hydroxide and HCl.

Answer 42

Mg(OH)2 + 2HCl ->MgCl2 + 2H2O

Question 43

Why is Mg(OH)2 safe to use?

Answer 43

It is weakly alkaline.

Question 44

Why is it preferable to using calcium carbonate?

Answer 44

It won't produce CO2.

Question 45

Describe the solubility of group 2 sulphates down the group.

Answer 45

Decreases.

Question 46

What is Mg(OH)2 also known as?

Answer 46

Milk of Magnesia

Question 47

What is BaSO4 also known as?

Answer 47

Barium meal

Question 48

What is the barium meal used for?

Answer 48

Diagnosing stomach problems. It coats the tissues then shows up on xrays

Question 49

Why is barium meal safe to ingest?

Answer 49

It is insoluble so it won't dissolve into the blood.

Question 50

How does calcium hydroxide appear?

Answer 50

White precipitate

Question 51

What is calcium hydroxide also known as?

Answer 51

Slaked lime

Question 52

What is slaked lime used for?

Answer 52

Neutralise acidity in soil.

Question 53

What is an aqueous solution of calcium hydroxide known as?

Answer 53

Lime water

Question 54

What is lime water used for?

Answer 54

Testing carbon dioxide. Turns cloudy as white calcium carbonate is produced.

Question 55

Equation for calcium hydroxide and CO2.

Answer 55

Ca(OH)2 + CO2 -> CaCO3 + H2O

Question 56

What is MgSO4 also known as?

Answer 56

Epsom salt

Question 57

What is epsom salt?

Answer 57

A mineral used to replace magnesium in the body, to increase water in intestines, as a laxative, relieve muscle pain, control seizures during pregnancy.

Question 58

How do you test for sulfate ions?

Answer 58

Use acidified BaCl2

Question 59

Equation for testing for sulfate ions?

Answer 59

BaCl2 + SO42- -> White precipitate of BaSO4

Question 60

Why do we acidify BaCl2?

Answer 60

Other anions, e.g. sulphites, will give the same result of a white ppt if not acidified, but if acidified in sulphites the ppt will dissolve)

Question 61

Why wouldn't we use H2SO4 to acidify the BaCl2?

Answer 61

The sulphuric acid itself would form a white ppt since it contains SO42- ions