Group 2

Question 1

What is a common name given to the group 2 metals?

Answer 1

Alkaline earth metals

Question 2

Why are group 2 metals known as reducing agents?

Answer 2

Group 2 metals undergo redox reactions. The group 2 metal is oxidised as it loses 2 valence electrons to form a 2+ ion.

Because it reduces another species by donating the 2 e- lost, it is a reducing agent as it reduces the other species.

Question 3

Describe the trend in reactivity of group 2 on the periodic table.

Answer 3

As you go down group 2, the metals get more reactive and become stronger reducing agents.

This is because as you go down the group, ionisation energies decrease as it becomes easier and requires less energy to lose the 2 electrons.

Due to increased atomic radius and increased shielding as you go down the group.

Question 4

What are the 3 factors which affect ionisation and reactivity of group 2 metals?

Answer 4

1. Increased atomic radius -> as you go down the group, the distance of the valence electron to the nucleus increases, which weakens the electrostatic force of attraction between the valence electron and the nucleus.
2. Increased shielding -> as you go down the group, there is more full inner shells which repel the electrons in the outer shells, preventing them to feel the nuclear charge. Therefore more shielding = lower ionisation energy = more reactive.
3. Increased nuclear charge. Although the other 2 factors outweigh this one, as the atom increases in size, the electrostatic force of attraction between the nucleus and outer electron becomes stronger and requires more energy to overcome.

Question 5

What are 3 properties of group 2 metals?

Answer 5

High MP and BP

Low density

Form white compounds.

Question 6

Describe the trend in first ionisation energy as you go down group 2.

Answer 6

First ionisation energy decreases due to increased atomic radius and shielding, weakening the electrostatic force of attraction between the nucleus and valence electron, therefore requires less energy to remove the electron.

Question 7

What type of reaction do group 2 metals undergo?

Answer 7

Redox reactions.

Question 8

What are the 3 reactions of group 2 metals that we need to know?

Answer 8

Reactions of group 2 with oxygen to produce a metal oxide.

Reactions of group 2 with water to produce a hydroxide and hydrogen gas.

Reactions of group 2 with acids. Produces a metal salt and hydrogen gas.

Question 9

Write an equation for the reaction of Calcium with oxygen.

Answer 9

2Ca (s) + O2(g) -> 2CaO(s)

Question 10

What is the product of the reaction of a group 2 metal with water?

Answer 10

A metal hydroxide and hydrogen gas.

Question 11

Which group 2 metal doesn’t react with water at normal temperatures and why?

Answer 11

Beryllium -> due to its small atomic size, high ionisation and high electronegativity, it can not displace hydrogen gas from water.

Question 12

Write an equation for the reaction of Barium and water.

Answer 12

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

Question 13

What are the products when a group 2 metal reacts with an acid?

Answer 13

A salt and hydrogen gas.

Question 14

Write an equation for the reaction of calcium with hydrochloric acid.

Answer 14

Ca(s) + 2HCl(aq) -> CaCl(s) + H2(g)

Question 15

What is the product when a group 2 metal OXIDE reacts with water?

Answer 15

A metal hydroxide

Question 16

Write an equation for the reaction between magnesium oxide and water.

Answer 16

MgO(s) + H2O(l) -> Mg(OH)2 (aq)

Question 17

What group 2 metal oxide is insoluble in water?

Answer 17

beryllium oxide

Question 18

What is the trend in solubility down group 2?

Answer 18

Solubility increases down the group.

Question 19

How do group 2 metals form alkaline solutions?

Give the equation of an example of how an alkaline solution is produced.

What does further saturation of the solution produce?

Answer 19

The group 2 metal OXIDES dissolve in water and release OH- ions to form alkaline solutions.

E.g.
CaO(s) + H2O(l) -> Ca2+ (aq) + 2OH-(aq)

Further saturation of the solution
Ca2+(aq) + 2OH-(aq) -> Ca(OH)2(s)

Question 20

What is the trend in the strength of the alkaline solution as you go down the group?

Answer 20

As you go down the group, solutions become more strongly alkaline due to increased solubility, resulting in more OH- in the solution.

Question 21

What is Ca(OH)2 used for?

Give the equation.

Answer 21

Ca(OH)2 is used to neutralise the pH of acidic soil.

Ca(OH)2(s) + 2H+(aq) -> Ca2+(aq) + 2H2O(l)

E.g. for HCl

Ca(OH)2(s) + 2HCl(aq) -> CaCl(aq) + 2H2O(l)

Question 22

What is Mg(OH)2 used for?

Answer 22

Milk of magnesia - an antiacid used in suspension to neutralise excess HCl in the stomach, relieving indigestion and heartburn.

Question 23

What is calcium carbonate used for?

Give the equation

What are the strengths and weaknesses of it?

Answer 23

To neutralise acidic soil. It is cheaper and safer to handle than Ca(OH)2 however is insoluble in water therefore acts more slowly.

CaCO3(s) + 2H+ -> Ca2+ + H2O + CO2

Question 24

What is a used of BaSO4?

Answer 24

Barium meal in medical imaging.

A patient drinks barium meal before having an X-ray of digestive system. BaSO4 coats the tissues and allows soft gut to be seen on X-ray.

Barium compounds are toxic but barium sulphate is safe to ingest because its insoluble therefore not absorbed into the bloodstream.