3.3.2 Discuss the changes in nature, from ionic to covalent and from basic to acidic, of the oxides across period 3.

As you go across period 3, nature of oxides changes from basic to acidic.

Oxide	Acid or base
Na2O	Basic Giant Ionic
MgO
Al2O3 - giant ionic	Amphoteric
SiO2 - giant covalent
P4O10	Acidic Molecular covalent
SO3/SO2
Cl2O7

Amphoteric: 

• posses properties of both acids and bases.
• when it reacts with an acid, it behaves as a base, and vice-versa. 
• tested with aluminum oxide
• When aluminum oxide reacts with an acid such as hydrochloric, aluminum oxide acts as a base.
• Al₂O₃ (s) + 6HCl (aq) → 2AlCl₃ (aq) + 3H₂O (l)
• Now, when aluminum oxide reacts with a base such as Sodium hydroxide, it acts as an acid.
• Al₂O₃ (s) + 2NaOH (aq) + 3H₂O (l) → 2NaAl(OH)₄

Reactions between Na₂O, MgO, P₄O₁₀  and SO₃  and water.

• Na₂O (s) + H₂O (l) →2NaOH (aq)
• Sodium oxide + water → Sodium hydroxide
• MgO (s) + H₂O (l)→ Mg(OH)₂ (aq)
• Magnesium oxide + water → Magnesium oxide
• P₄O₁₀ (s) + 6H₂O (l) → 4H₃PO₄
• Phosphorous (v) oxide + water → Phosphoric (V) acid
• SO₃(l) + H₂O (l) → H₂SO₄(aq)
• Sulfur trioxide + water → Sulfuric (VI) acid.

Across a period 3, there is a change from metallic to non-metallic. 

• Left. ex) Sodium, Magnesium and Aluminium all have the typical properties of metallic substances (E.g. good conductors of electricity), 
• Righ. ex) such as Chlorine and Sulfur are non-metals.

Metals will react to form ionic compounds. 

Non-metals will react to form covalent compounds.