Period 3 Flashcards
Explain why sodium is more reactive than magnesium.
→ Na has a lower nuclear charge
→ weaker attraction between nucleus & outer electron
→ ∴ outer e- is lost more easily than in Mg
Describe the reaction between sodium and cold water. Give the equation.
→ reacts vigorously, forms a ball + fizzes
2Na + 2H₂O → 2NaOH + H₂
Describe the reaction between magnesium and cold water. Give the equation.
→ reacts slowly, forms weak alkaline solution
Mg + 2H₂O → Mg(OH)₂ + H₂
Describe the reaction between magnesium and steam. Give the equation.
→ fast reaction
Mg (s) + H₂O (g) → MgO (s) + H₂ (g)
Explain why the reaction between magnesium and water produces a weak alkaline solution.
→ Mg(OH)₂ is produced which is sparingly soluble
→ ∴ low concentration of OH- in solution
State the formulas of the compounds formed when period 3 elements react with oxygen.
→ Na₂O
→ MgO
→ Al₂O₃
→ SiO₂
→ P₄O₁₀
→ SO₂
How is SO₃ made?
→ reaction between sulfur & oxygen
→ at high temperature
→ with a catalyst
Explain why MgO has a higher melting point than Na₂O.
→ MgO lattice consists of 2+ ions which are more strongly attracted to oxygen ions
→ stronger ionic bonding ∴ more energy required
Explain why Al₂O₃ has a lower melting point than MgO.
- Al³⁺ ions distort oxygen’s electron cloud
- this means there is some covalent character
- ∴ less energy required to break the bonds
Explain why silicon dioxide has a high melting point (compared to other non-metal oxides).
→ macromolecular structure
→ with many strong covalent bonds
→ requires high amounts of energy to breaks
Explain why P₄O₁₀ and SO₂ have low melting points.
→ simple molecular structures
→ so weak intermolecular forces (VDW)
→ less energy required
How do period 3 oxides react with water?
ionic oxides → form hydroxides
non-metal oxides → form acids
Give the equation for the reaction between sodium oxide and water. State the pH of the solution formed.
Na₂O + H₂O → 2NaOH
pH 13
Give the equation for the reaction between magnesium oxide and water. State the pH of the solution formed.
MgO + H₂O → Mg(OH)₂
pH 9
Give the equation for the reaction between phosphurus oxide and water. State the pH of the solution formed.
P₄O₁₀ + 6H₂O → 4H₃PO₄
pH 0
Give the equation for the reaction between sulfur dioxide and water. State the pH of the solution formed.
SO₂ + H₂O → H₂SO₃
pH 3
Give the equation for the reaction between sulfur trioxide and water. State the pH of the solution formed.
SO₃ + H₂O → H₂SO₄
pH 0
State why silicon dioxide and aluminium oxide do not react with water.
insoluble in water due to their structures
Explain what is meant by the term amphoteric.
acts as both a base and an acid
State which period 3 oxide is classified as amphoteric.
aluminium oxide
Reaction between magnesium oxide and hydrochloric acid.
MgO + 2HCl → MgCl₂+ H₂O
Reaction between sodium oxide and hydrochloric acid.
Na₂O + 2HCl → 2NaCl + H₂O
Reaction between sodium oxide and sulfuric acid.
Na₂O + H₂SO₄ → Na₂SO₄ + H₂O
Reaction between phosphurus oxide and sodium hydroxide.
P₄O₁₀ + 12NaOH → 4Na₃PO₄ + 6H₂O
Reaction between phosphurus oxide and sodium oxide.
P₄O₁₀ + 6Na₂O → 4Na₃PO₄
Reaction between sulfur dioxide and sodium hydroxide.
SO₂ + 2NaOH → Na₂SO₃ + H₂O
Reaction between sulfur trioxide and sodium hydroxide.
SO₃ + 2NaOH → Na₂SO₄ + H₂O
Reaction between silicon dioxide and sodium hydroxide.
SiO₂ + 2NaOH → Na₂SiO₃ + H₂O
Give the equation for the reaction of aluminium oxide as an acid.
Al₂O₃ + 2NaOH + 3H₂O → 2NaAl(OH)₄
Give the equation for the reaction of aluminium oxide as a base with sulfuric acid.
3H₂SO₄ + Al₂O₃ → Al₂(SO₄)₃ + 3H₂O
Give the equation for the reaction of aluminium oxide as a base with hydrochloric acid.
Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O
Describe the appearance of the reaction between sodium and oxygen.
→ yellow flame
→ produces a white solid
Describe the appearance of the reaction between sulfur and oxygen.
→ burns with a blue flame
→ forms an acidic choking gas
Describe the appearance of the reaction between the elements oxygen and Mg, Al, Si, P respectively.
→ white flame
→ white solid smoke
Explain, using an equation, why silicon(IV) oxide is classified as an acidic oxide.
Reacts with bases
SiO2 + 2NaOH → Na2SiO3 + H2O
