Properties of Period 3 elements and their oxides (A2 Inorganic)

Question 1

Reaction of Na and Water

Answer 1

2Na(s) + 2H2O(l) —> 2NaOH(aq) + H2(g)

• Vigorous reaction
• Na is less dense so it floats on the water, bubbles are seen
• NaOH- alkaline and colourless, dissociates into OH- ions

Question 2

Reaction of Mg with Water

Answer 2

Mg(s) + H2O(l) —> Mg(OH)2 (aq) + H2 (g)
- Very slow reaction
- Mg(OH)2 is slightly alkaline

Question 3

What type of reaction is it when Mg reacts with steam in the absence of air?

Answer 3

• A very vigorous reaction
• Mg(s) + H2O(g) –> MgO(s) + H2(g)
• MgO is a white solid
• Burns with bright white light

Question 4

Na2O- metal oxide

Answer 4

• Ionic, basic
• White solid, forming giant ionic lattice
• High MP and BP, conducts electricity when in aqueous (freely moving ions)

Question 5

Formation of Na2O + observations

Answer 5

4Na(s) + O2 (g) —> 2Na2O
- Burns with a yellow flame producing a white solid

Question 6

Reaction of Na2O with water

Answer 6

Na2O + H2O —> 2NaOH
NaOH —> Na+ + OH- (ph 12-14)

Question 7

Reactions of Na2O with acid

Answer 7

Na2O (s) + 2HCl (aq) —> 2NaCl(aq) + H2O (l)
Na2SO4 (s) + H2SO4 (aq) —> Na2SO4 (aq) + H2O (l)

Question 8

MgO- Metal Oxide

Answer 8

Ionic, basic, slightly soluble
- White solid, giant ionic lattice
- High MP / BP, conducts electricity when dissolved

Question 9

Formation of MgO

Answer 9

2Mg(s) + O2 (g) —> 2MgO
- Burns with bright white flame, white solid

Question 10

Reaction of MgO with Water

Answer 10

MgO (s) + H2O (l) —> Mg(OH)2 (aq) - pH 9
- Slightly soluble so only a little reacts

Question 11

Reaction of MgO with acids

Answer 11

MgO (s) + HCl (aq) —> MgCl2 (aq) + H2O(l)
MgO (s) + 2HNO3 (aq) —> Mg(NO3)2 (aq) + H2O (l)

Question 12

Al2O3- Metal Oxide

Answer 12

• Ionic, amphoteric oxide
• White solid, giant ionic lattice
• Ionic compound with covalent character
• High MP, conducts when dissolved

Question 13

Formation of Al2O3

Answer 13

4Al +3O2 –> 2Al2O3
- Powder burns easily, foil has protective oxide- does not react as readily produces white solid

Question 14

Reaction of Al2O3 with water

Answer 14

• Does not react
• Insolunole, very strong ionic bonds- Al3+ small and high charge density

Question 15

Reaction of Al2O3 with acids and bases (its amphoteric)

Answer 15

Al2O3 + 6HCl –> 2AlCl3 + 3H2O
Al2O3 + 2NaOH —> NaAl(OH)4 + 3H2O