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Period 3 elements form compounds of oxides and chlorides

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Period 3 elements form compounds of oxides and chlorides

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SiCl4 (s) + 2H2O (l) ® SiO2 (g) + 4HCl (aq)

If water is added:
- a violent reaction occurs to produce silicon dioxide and fumes of hydrogen chloride.

In a large excess of water:
- hydrogen chloride will dissolve to give hydrochloric acid.

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Eq of cold water: PCl5 (s) + H2O (l) -> POCl3 (g) + 2HCl (aq)
Eq of boiling water: PCl5 (s) + 4H2O (l) -> H3PO4 (aq) + 5HCl (aq)
-> when there is enough water present to dissolve PCI5 -> HCl

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Aluminium hydroxide reacts with sodium hydroxide
It will give a colourless solution of sodium tetrahydroxoaluminate.
Al(OH)3 (s) + NaOH (aq) --> NaAl(OH)4 (aq)

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MgCl2 (s) + 6H2O (l) -> [Mg(H2O)6]2+ (aq) + 2Cl- (aq)
- forms Hexaaquamagnesium ions
[Mg(H2O)6]2+

[Mg(H2O)5(OH0]+ and H3O+
- more H + present in the solution
- faintly acidic solution

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Magnesium hydroxide reacts with acids to form salts.
Mg(OH)2 (s) + 2HCl (aq) --> MgCl2 (aq) + 2H2O (l)
Mg(OH)2 (s) + H2SO4 (aq) --> MgSO4 (aq) + 2H2O (l)

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Eq: AlCl3 (s) + 6H2O (l) -> [Al(H2O)6]3+ (aq) + 3Cl- (aq)
-> form Hexaaquaaluminium ions [Al(H2O)6]3+

Eq: [Al(H2O)6]3+ (aq) + H2O (l) <-> [Al(H2O)5(OH)]2+ (aq) + H3O+ (aq)
-> Al3+ and H2O molecules form co-ordinate (dative covalent) bonds.
-> H2O more positive and easier to remove, making it more acidic.

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Sodium hydroxide react with acid to form salts.
NaOH (aq) + HCl (aq) --> NaCl (aq) + H2O (l)
2NaOH (aq) + H2SO4 (aq) --> Na2SO4 (aq) + 2H2O (l)

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Al₂O3 (s) + 2NaOH (aq) + 3H₂O (l) → 2NaAl(OH)4 (aq)

SiO2 (s) + 2NaOH (aq) → Na₂SiO3 (aq) + H₂O (l)

P₄O10 (s) + 12NaOH (aq) → 4Na₃PO4 (aq) + 6H₂O (l)

SO₃ (g) + 2NaOH (aq) → Na₂SO₄ (aq) + H₂O (l)

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Na₂O (s) + 2HCl (aq) → 2NaCl (aq) + H₂O (l)

MgO (s) + 2HCl (aq) → MgCl2 (aq) + H₂O (l)

Al₂O₃ (s) + 6HCl (aq) → 2AlCl3 (aq) + 3H₂O (l)

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Na₂O (s) + H₂O (l) → 2NaOH (aq)

MgO (s) + H₂O (l) → Mg(OH)2 (s)

Al₂O₃ does not react with water → ions held strongly in the lattice

SiO₂ does not react with water → Si and O atoms are held strongly by covalent bonds, giant covalent structure

P₄O10 (s) + 6H₂O (l) → 4H₃PO₄ (aq)

SO3 (g) + H₂O (l) → H₂SO₄ (aq)

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- simple molecule
- low melting & boiling point: weak Van der Waals force between molecules
- does not conduct electricity: no free electrons

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- giant covalent structure
- HIGHEST melting & boiling point: strong covalent bonds between atoms
- does not conduct electricity: no free electrons, only able to conduct electricity at high temp

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- Amphoterism can react with both acids and bases, acting as an acid in the presence of a base and as a base in the presence of an acid.
- Aluminium hydroxide reacts with hydrochloric acid to form aluminium chloride.
Al(OH)3 (s) + 3HCl (aq) --> AlCl3 (aq) + 3H2O (l)

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- metallic structure
- high melting & boiling point: strong metallic bonding between metal nucelus & sea of electrons
- conduct electricity: electrons delocalised (able to move freely)

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Reaction with its chloride (Lisa & Pei Shan)

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Reaction with its chloride (Lisa & Pei Shan)