Flashcards · 7405 · A Level Topic 16

Properties of Period 3 elements and their oxides (A Level) flashcards

8 cards on A Level Topic 16. Pick a subtopic or study them all.

Study mode needs JavaScript. Every card is listed below, so you can still cover the answers and test yourself.

All 8 cards

For a quick read-through or printing. Cover the right-hand side to test yourself.

Amphoteric oxide: Reacts with both acids and bases (Al₂O₃).
Sodium vs magnesium with cold water: Na: vigorous, 2Na + 2H₂O → 2NaOH + H₂, pH 13–14. Mg: very slow, Mg + 2H₂O → Mg(OH)₂ + H₂, pH 9–10.
Equations: P₄O₁₀, SO₂ and SO₃ with water: P₄O₁₀ + 6H₂O → 4H₃PO₄ SO₂ + H₂O → H₂SO₃ SO₃ + H₂O → H₂SO₄
Why do Al₂O₃ and SiO₂ give pH 7 with water?: Both are insoluble: their giant structures are too strongly bonded to dissolve. They are not neutral oxides: Al₂O₃ is amphoteric and SiO₂ is acidic.
Why does MgO have a higher melting point than Na₂O?: Both are giant ionic, but Mg²⁺ has a higher charge and is smaller than Na⁺, so the attraction to O²⁻ is stronger.
Why does P₄O₁₀ have a low melting point?: It is simple molecular: only van der Waals forces between molecules are overcome, not covalent bonds.
Al₂O₃ with an acid and with sodium hydroxide: Al₂O₃ + 6H⁺ → 2Al³⁺ + 3H₂O Al₂O₃ + 2OH⁻ + 3H₂O → 2Al(OH)₄⁻
SiO₂ with sodium hydroxide: Only with hot, concentrated NaOH: SiO₂ + 2OH⁻ → SiO₃²⁻ + H₂O