Chapter 10: Group 2

Question 1

What do metals form when they react with oxygen?

Answer 1

Metal Oxides

Question 2

Describe and explain the reaction of beryllium with oxygen.

Answer 2

Beryllium is reluctant to burn with oxygen unless it is in a dust form
This is because it has a strong thin layer of oxide that stop it from making contact with the oxygen

Question 3

How does beryllium look when burning in a flame?

Answer 3

With silvery sparkles

Question 4

Magnesium’s flame?

Answer 4

Intense white

Question 5

How does calcium burn?

Answer 5

Initially it is reluctant

Then suddenly starts burning with an intense white flame with red tinges at the end

Question 6

How does strontium burn?

Answer 6

Initially does not burn
Then suddenly starts burning
With red tinges around the outside

Question 7

How does barium burn?

Answer 7

With a pale green flame

Question 8

What are the 2 group 2 elements that burn to form peroxides?

Answer 8

Barium and Strontium

Question 9

Describe the burning and the conditions required to for strontium peroxide.

Answer 9

Strontium will have to be heated with oxygen under very high pressures

Question 10

How does barium peroxide form?

Answer 10

The barium will produce barium peroxide and barium dioxide when just normally heated with oxygen

Question 11

Describe the reaction of a group 2 metal with air.

Answer 11

They will form the respective metal oxide and the metal nitride

Question 12

Why does the activation energy of a reaction fall?

Answer 12

Because the ionisation energies are falling

Question 13

Describe the polarisation of a negative peroxide ion.

Answer 13

As the ion with a positive charge gets closer the electrons are attracted to it and then it increases the chance of a simple oxide forming.

Question 14

Why is barium able to form a peroxide ion but not other group 2 metals?

Answer 14

Its higher shielding means that the positive charge is not strong enough to break up the nitride molecule

Question 15

Why can group 2 form nitrides but not group 1

Answer 15

The higher charge compensates for the energy loss by releasing more energy due to a higher lattice energy.

Question 16

Describe the reactivity of magnesium in cold water

Answer 16

It will react tot form a weakly alkaline solution.

Question 17

When do we get magnesium oxide and hydrogen when reaction magnesium with water?

Answer 17

When the magnesium is hot and the the water is in the form of steam.

Question 18

Describe the reaction of calcium with water

Answer 18

It reacts more readily
It forms calcium hydroxide solution that is weakly alkaline
Hydrogen gas is given off

Question 19

What is the trend with the reaction of water of group 2 metals?

Answer 19

The hydrogen gas is given off more rapidly.

Question 20

What happens when water is added to calcium hydroxide?

Answer 20

There is a very exothermic reaction
Calcium hydroxide is produced
The calcium hydroxide swells up and lots of steam is produced

Question 21

How do we form lime water?

Answer 21

Very small amounts of calcium oxide is added to water that forms a strongly alkaline solution.

Question 22

Describe the trend of solubilities going down group 2.

Answer 22

The solubilities of the hydroxide increases going down the group, and therefore the resulting solution will have higher pH’s.

Question 23

Describe the trend of group 2 sulphates going down the group.

Answer 23

The sulphates become less and less soluble.

Question 24

Describe the reaction of a group 2 oxide with a dilute acid.

Answer 24

Since they are all basic oxides, they will just give salt and water

Question 25

Describe the reactions of a group 2 metals with a dilute sulphuric acid.

Answer 25

They make their respective sulphate salts.

However, calcium sulphate os only sparingly soluble while barium sulphate is not at all soluble.

Question 26

What is the trend in the solubility of sulphates?

Answer 26

The sulphates become less soluble as you go down the group

Question 27

Describe the trend is the solubilities of carbonates as you go down the group.

Answer 27

The tend to become less soluble going down.

Question 28

How do carbonates react with dilute acids?

Answer 28

They give the salt, carbon dioxide and water.

Question 29

Describe the trend in the thermal decomposition of carbonates going down the group?

Answer 29

The carbonates tend to become more and more thermally stable going down the group

Question 30

What do the carbonates produce going down the group?

Answer 30

They produce the metal oxide and carbon dioxide.

Question 31

What is the gas that forms when group 2 nitrates are heated

Answer 31

It forms the NO2 gas that is brown and toxic.

Question 32

What is the trend in atomic radius of group 2?

Answer 32

The atomic radius increases as you go down the group

Question 33

What is the trend of the first Ionisation energy of the elements in group 2.

Answer 33

It falls going down the group

Question 34

What is the trend of electronegativity going down the group?

Answer 34

it falls.

The atoms become less and less good at attracting the pair of electrons.

Question 35

Why can beryllium not form ions?

Answer 35

The size of the atom is too small, and so the electron pair is held very strongly
Even in the state of a bond, the pair is brough much closer to the beryllium nucleus.

Question 36

Describe the trend of melting points of group 2.

Answer 36

It decreases down the group except for magnesium which has a veyr low melting point.

Question 37

What is the general trend when a metal reacts with cold water and when it reacts with steam. What is the reason for this?

Answer 37

Cold water - Metal Hydroxide
Steam - Metal Oxide
Reason - At the high steam, the metal hydroxides thermally decompose to give the oxide and water.

Question 38

How do calcium, strontium and Barium react with cold water?

Answer 38

They react with increasing vigour to give the hydroxide and hydrogen.
The reaction is very exothermic.

Question 39

What is the trend of the hydroxides that form when group 2 reacts with steam?

Answer 39

The hydroxides get increasingly soluble, with calcium being a precipitate.

Question 40

What is the role of lime in agriculture?

Answer 40

To raise the soli pH