Group 2 - alkaline earth metals

Question 1

Q: Why does atomic radius increase down Group 2?

Answer 1

• More electron shells
• Outer electrons further from nucleus

Question 2

Q: Why does first ionisation energy decrease down Group 2?

Answer 2

• More shielding
• Outer electrons further from nucleus
• Weaker attraction = easier to remove

Question 3

Q: Why does reactivity increase down Group 2?

Answer 3

• Outer electrons are lost more easily
• Increased atomic radius and shielding
• Lower ionisation energy

Question 4

Q: Write an equation for calcium reacting with water.

Answer 4

Ca + 2H₂O → Ca(OH)₂ + H₂

Question 5

Q: Describe the trend in solubility of Group 2 hydroxides

Answer 5

• Solubility increases down the group
• Mg(OH)₂ = sparingly soluble
• Ba(OH)₂ = very soluble

Question 6

Q: Describe the trend in solubility of Group 2 sulfates.

Answer 6

• Solubility decreases down the group
• BaSO₄ is insoluble

Question 7

Q: Why is BaSO₄ safe to use in a barium meal, even though Ba²⁺ is toxic?

Answer 7

BaSO₄ is insoluble, so Ba²⁺ ions are not released

Question 8

Q: Describe the test for sulfate ions.

Answer 8

• Add dilute HCl (removes interfering ions)
• Add BaCl₂ solution
• White precipitate of BaSO₄ confirms sulfate

Question 9

Q: What is Ca(OH)₂ used for in agriculture?

Answer 9

To neutralise acidic soils

Question 10

Q: Why does magnesium react slowly with cold water but faster with steam?

Answer 10

• Reaction with cold water is very slow due to low reactivity
• Steam provides more energy → faster reaction

Question 11

Q: Write an ionic equation for the reaction between Ba²⁺ and SO₄²⁻ ions.

Answer 11

Ba²⁺ (aq) + SO₄²⁻ (aq) → BaSO₄ (s)

Question 12

Q: Which compound is used to remove SO₂ in flue gases and why?

Answer 12

• CaO or CaCO₃
• They react with sulfur dioxide to neutralise it and reduce air pollution