Properties of Period 3 Elements and their Oxides: Reactions of Na & Mg With Water

Question 1

Some period 3 elements react with water. Which ones must you know of?

Answer 1

• Na
• Mg

Question 2

Describe the reaction between sodium and water

Answer 2

• Na reacts vigorously

Question 3

Give the equation for the reaction between sodium and water

Answer 3

2Na_(s) + 2H₂O_(l) → 2NaOH_(aq) + H_2(g)

Question 4

Describe the reaction between magnesium and water

Answer 4

• Mg reacts very slowly with water
• Mg reacts vigorously with steam

Question 5

Give the equation for the reaction between magnesium and cold water

Answer 5

Mg_(s) + 2H₂O_(l) → Mg(OH)_2(aq) + H_2(g)

Question 6

Give the equation for the reaction between magnesium and steam

Answer 6

Mg_(s) + H₂O_(g) → MgO_(s) + H_2(g)

Question 7

Which element is more reactive: sodium or magnesium?

Answer 7

• Sodium

Question 8

Why is sodium more reactive than magnesium?

Answer 8

• Sodium only has to lose 1 electron to form an ion, whereas magnesium has to lose 2
• Less energy is required to ionise sodium, making it more reactive