Period 3 Elements

Question 1

Which is more reactive from Na and Mg? (1 mark)

Answer 1

⦾ Na (1)

Question 2

Which has the higher melting point from Na and Mg?

1 mark

Answer 2

⦾ Mg (1)

Question 3

Why is Sodium more reactive than Magnesium? (3 marks)

Answer 3

⦾ Na from group 1 and Mg from group 2 (1)
⦾ (so) Na loses 1e- to form Na+and Mg loses 2e- to form Mg2+ (1)
⦾ (therefore) less energy to lose 1e- than 2e- (1)

Question 4

What can be observed when sodium reacts with cold water? (4 marks)

Answer 4

⦾ vigorously (1)
⦾ molten ball on surface (1)
⦾ (produces) H2 gas (1)
⦾ (and) strongly alkaline solution (1)

Question 5

Why is an alkaline solution produced when sodium reacts with cold water? (1 mark)

Answer 5

⦾ NaOH produced (1)

Question 6

What is the balanced equation for the reaction of sodium with cold water? (2 marks)

Answer 6

⦾ 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g) (2)

Question 7

What can be observed when magnesium reacts with cold water?

Answer 7

⦾ very slowly - not very soluble (1)
⦾ thin magnesium hydroxide coating on surface of metal (1)
⦾ (produces) H2 gas (1)
⦾ weakly alkaline (1)

Question 8

What is the balanced equation for the reaction of magnesium with cold water? (2 marks)

Answer 8

⦾ Mg(s) + 2H2O(l) → Mg(OH)2(aq) + H2(g) (2)

Question 9

What is produced when magnesium reacts with steam?

Answer 9

⦾ MgO(s) and H2(g) (1)

Question 10

What is the balanced equation for the reaction of magbesium with cold water? (1 mark)

Answer 10

⦾ Mg(s) + H2O(g) → MgO(s) + H2(g) (1)

Question 11

What do most period 3 elements form when they react with oxygen? (1 mark)

Answer 11

⦾ oxides