Group 2 Metals

Question 1

How does atomic radium change down the group?

Answer 1

Increases
Extra electron shell, outer electron further from nucleus and more shielded
Increased nuclear charge outweighed by greater shielding and distance

Question 2

How does first ionisation energy change down the group?

Answer 2

Decreases down the group
Extra electron shell, outer electron further from nucleus and more shielded
Increased nuclear charge outweighed by greater shielding and distance

Question 3

How does electronegativity change down the group?

Answer 3

Less electronegative down the group

As bonding pair is further away from the nucleus

Question 4

How do melting and boiling points change down the group?

Answer 4

Decrease
Metallic bonding gets weaker down the group
Ionic radius of metal ions increases down group so charge density decreases. Weaker attraction between metal ions and delocalised electrons

Question 5

How does atomisation energy change down the group?

Answer 5

It decreases due to weaker metallic bonding

Increased shielding and greater atomic radius

Question 6

What is the equation for the reaction Mg and water?

Answer 6

Mg(s) + H20(g) to MgO(s)+ H2(g)

Question 7

What is the equation for the reaction Ca and water?

Answer 7

Ca(s) + 2H2O(l) to Ca(OH)2(s) + H2(g)

Question 8

What is the equation for the reaction Sr and water?

Answer 8

Sr(s) + 2H2O(l) to Sr(OH)2(aq) + H2(g)

Question 9

What is the equation for the reaction Ba and water?

Answer 9

Ba(s) + 2H2O(l) to Ba(OH)2(aq) + H2(g)

Question 10

How does reactivity with water change down the group?

Answer 10

Since ionisation energies decrease down a group, the electrons are more easily removed from the atoms and the reaction with water becomes increasingly vigorous on descending group II.

Question 11

what is the trend in solubility of the sulphates?

Answer 11

The solubility of the sulphates decreases down group II

MgSO4 is soluble, CaSO4 is sparingly soluble and SrSO4 and BaSO4 are insoluble

Question 12

Barium is insoluble, how can this be used?

Answer 12

To test for the presence of sulphate ions, SO4

Question 13

What is the trend in solubility of the hydroxides?

Answer 13

As solubility increases, more OH- ions are released.
This makes a more alkaline solution.
The pH increases down the Group

Question 14

How can adding hydroxides to group 2 metals identify them?

Answer 14

As Mg(OH)2 is sparingly soluble, a thick white precipitate is formed.
As Ba(OH)2 is more soluble, a thin white precipitate will be formed

Question 15

How can adding sulphates to group 2 metals identify them?

Answer 15

As MgSO4 is soluble, no precipitate will form.

As BaSO4 is insoluble, a white precipitate will be formed.

Question 16

What is the test for sulphate ions?

Answer 16

Add HCl first – This reacts and removes any sulphites or carbonates that may also give a white precipitate.
Add BaCl2 solution: If sulphates are present, a white precipitate of BaSO4 will form.

Question 17

What is the equation for the reaction between barium and sulphate ions?

Answer 17

Ba2+(aq) + SO42-(aq) to BaSO4(s)

Question 18

In the flame test what colour will calcium strontium and barium burn?

Answer 18

Ca+ - brick red
Sr2+ - red
Ba2+ - pale green

Question 19

How can barium have a medical application?

Answer 19

Barium sulphate, BaSO4, does not allow X – rays to pass through.
Drinking a suspension of BaSO4 coats the oesophagus, stomach or intestines (Barium
meal)
These now show up on an X – Ray allowing you to see any problems.
Other Group 2 metal compounds are soluble so cannot be used.

Question 20

How can group 2 metals help in the extraction of titanium? Give an equation:

Answer 20

TiO2 is converted to TiCl4 by heating with carbon and chlorine
TiCl4 is then reduced by Mg:
TiCl4(g) + 2Mg(l) to Ti(s) + 2MgCl2(l)
Magnesium reduces titanium

Question 21

How can you remove SO2 from flue gases?

Answer 21

SO2 is produced burning fossil fuels to make electricity.
This can be removed by reacting with an alkali such as CaO or CaCO3 slurry (mixed with
water)

Question 22

Give the equations for the extraction of SO4 from flue gases:

Answer 22

CaO(s) + 2H2O(l) + SO2(g) à CaSO3(aq) + 2H2O(l)

CaCO3(s) + 2H2O(l) + SO2(g) à CaSO3(aq) + 2H2O(l) + CO2(g)

Question 23

How can the alkaline earth metals neutralise acids?

Answer 23

Ca(OH)2 is used to neutralise acidic soils.

Mg(OH)2 is used to neutralise excess stomach acids as milk of magnese