Unit 2 Section 2: Group 2 And Group 7 Elements

Question 1

Explain why calcium has a higher melting point than strontium.

Answer 1

In calcium structures, the delocalised electrons are closer to the nuclei of the ions. This means there is stronger attraction between the cations and the electrons, so stronger metallic bonding and more energy to break the bonds.

Question 2

Write an equation for the reaction of magnesium with oxygen.

Answer 2

2Mg+O2->2MgO

Question 3

Write an equation for the reaction of magnesium with cold water.

Answer 3

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

Question 4

Give a medical use for the magnesium compound formed in the reaction of magnesium with cold water.

Answer 4

Magnesium hydroxide is used as an antacid (neutralises stomach acidity)