The alkaline earth metals

Question 1

Why are the elements in group 2 known as s-block elements?

Answer 1

Their highest energy (bonding) electrons are in s-orbitals

Question 2

Why does atomic radius increase down group 2?

Answer 2

The greater the atomic number the more electrons there are, additional electrons go into shells that are increasingly further from the nucleus

Question 3

Why does melting point decrease down group 2?

Answer 3

Each atom contributes two electrons to the
delocalised cloud, metallic bonding gets weaker
due to increased size of ion, Larger ions mean that the electron cloud doesn’t
bind them as strongly

Question 4

Why does first ionisation energy decrease down group 2?

Answer 4

Despite the increasing nuclear charge, the values
decrease due to the extra shielding provided by
additional filled inner energy levels

Question 5

Write a balanced equation with state symbols for the general reaction of a group 2 metal, M, with water

Answer 5

M (s) + 2H2O (g) → M(OH)2 (aq) + H2 (g)

Question 6

Write a balanced equation with state symbols for the reaction of magnesium with steam

Answer 6

Mg (s) + H2O (g) → MgO (s) + H2 (g)

Question 7

How is magnesium used in the extraction of titanium from titanium chloride? Write a balanced equation for this reaction.

Answer 7

Molten magnesium is used to reduce the
titanium(IV) chloride, TiCl4, to titanium, Ti
TiCl4 + 2Mg → Ti + 2MgCl2

Question 8

What is the trend in solubility of the group 2 hydroxides?

Answer 8

They get more soluble down the group

Question 9

Give one use of magnesium hydroxide and explain why it can be used for this application

Answer 9

Indigestion medicine (milk of magnesia)
It is slightly soluble so only forms a mildly alkaline
suspensio

Question 10

Give two uses of calcium hydroxide

Answer 10

1. In solution, as limewater – to test for CO2 gas
2. As a solid, in agriculture to control soil acidity

Question 11

What is the trend in solubility of the group 2 sulfates?

Answer 11

They get less soluble down the group?

Question 12

Given one use of barium sulfate and explain why it can be used for this application

Answer 12

Barium sulfate can be taken in by the mouth as a
‘barium meal’ to outline the gut in medical X-rays
It is insoluble

Question 13

Describe the chemical test for sulfate ions

Answer 13

1. Use barium chloride in the presence of dilute
   hydrochloric acid (it is acidified to remove
   impurities such as carbonate ions)
2. This will produce a white precipitate of barium
   sulfate if sulfate ions are present