Chemistry - Periodic Table

Reaction with Oxygen: Across Period 3, Na

Forming Na₂O (s),

4Na (s) + O₂ (g) > 2Na₂O (s)

Observation:

Very vigorous, burns with a brilliant yellow flame.

White Na₂O (s) is obtained

Reaction with Oxygen: Across Period 3, Mg

Forming MgO (s),

2Mg (s) + O₂ (g) > 2MgO (s)

Observation:

Very vigorous, burns with bright white light

White MgO (s) is obtained

Reaction with Oxygen: Across Period 3, Al

Forming Al₂O₃ (s),

4Al (s) + 3O₂ (g) > 2Al₂O₃ (s)

Observation:

Vigorous at first, burns with a white flame

White Al₂O₃ (s) formed on surface prevents further oxidation

Reaction with Oxygen: Across Period 3, Si

Forming SiO₂ (s),

Si (s) + O₂ (g) > SiO₂ (s)

Observation:

Burns with a white flame when heated to 400°C

White SiO₂ (s) is obtained

Reaction with Oxygen: Across Period 3, P

On limited O₂, forms P₄O₆ (s)

P₄ (s) + 3O₂ (g) > P₄O₆ (s)

On excess O₂, forms P₄O₁₀ (s)

P₄ (s) + 5O₂ (g) > P₄O₁₀ (s)

Observation:

Vigorous, burns with a bright white light or pale blue-green flame.

White P₄O₆ (s) or P₄O₁₀ (s) is obtained.

Reaction with Oxygen: Across Period 3, S

Forms, SO₂ (g)

S (s) + O₂ (g) > SO₂ (g)

or

S (s) + ½ O₂ (g) > SO₃ (g)

Observation:

Vigorous, burns with a blue flame

In excess O₂ with catalyst, SO₂ (g) can be further oxidised to SO₃ (g)

Reaction with Oxygen: Down G2, Ca

Forms CaO (s)

2Ca (s) + O₂ (g) > 2CaO (s)

Observation:

Very vigorous, burns with a brick-red flame

Reaction with Oxygen: Down G2, Sr

Forms SrO (s)
2Sr (s) + O₂ (g) > 2SrO (s)

Observation:

Very vigorous, burns with a crimson-red flame

Reaction with Oxygen: Down G2, Ba

Forms BaO (s)
2Ba (s) + O₂ (g) > 2BaO (s)

Observation:

Very vigorous, burns with apple green flame

Reaction of G2 with Water, Mg

1) Reacts SLOWLY with COLD WATER to form:

Mg (s) + H₂O (l) = Mg(OH)₂ (aq) + H₂ (g)

Observation:

Eff. H₂ (g) and white ppt of Mg(OH)₂ (s) formed in a weakly alkaline solution of Mg(OH)₂ (aq) (pH 9)

2) Reacts READILY with STEAM to form:

Mg (s) and H₂O (g) > MgO (s) + H₂ (g)

Observation:

Mg glows in steam to give a white residue of MgO and eff. H₂ (g)

Reaction of G2 with Water, Ca

Reacts READILY with COLD WATER to form

Ca (s) + H₂O (l) > Ca(OH)₂ (aq) + H₂ (g)

Observation:

Eff of H₂ (g) and strongly alkaline solution of pH 12 formed

White ppt of Ca(OH)₂ often observed due to its low solubility in water

Reaction of G2 with Water, Sr Ba

Reacts VIGOROUSLY with COLD WATER to form

M (s) + H₂O (l) > M(OH)2 (aq) + H₂ (g)

[M = Sr/ Ba]

Observation:
Eff of H₂ (g) and strongly alkaline solution of pH 13-14 formed

Reaction of P3 with Cl₂, Na

Forms: NaCl (aq)

2Na (s) + Cl₂ (g) > 2NaCl (s)

Observation:
Very vigorous, burns readily to give white solid og NaCl (s)

Reaction of P3 with Cl₂, Mg

Forms MgCl (s)
Mg (s) + Cl₂ (g) > MgCl₂ (s)

Observation:

Very vigorous, burns readily to give white solid of MgCl₂

Reaction of P3 with Cl₂, Al

Forms AlCl₃ (s)

2Al (s) + 3Cl₂ (g) > 2AlCl₃ (s)

Observation:

Slow at room temp,

Dry Cl₂ is passed over heated Al foil to form AlCl₃ which sublimes as pale yellow solid

Reaction of P3 with Cl₂, Si

Forms SiCl₄ (l)
Si (s) + 2Cl₂ (g) > SiCl₄ (l)

Observation:

Reaction is slow, colourless SiCl₄ (l) formed

Reaction of P3 with Cl₂, P

Forming PCl₅ (s)
1) P₄ (s) + 6Cl₂ (g) > 4PCl₃ (l)

PCl₃ (l) + Cl₂ (g) > PCl₅ (s)

2) Excess Cl₂

P₄ (s) + 10Cl₂ (g) > 4PCl₅ (s)

Observation:

Reaction is slow, off white solid of PCl₅ is formed

Properties of Na₂O (s)

MP/BP: High (Strong Ionic Bonds)

Acid/ base Nature: Basic

Reaction with water

• Reacts vigorously in water

• strongly alkaline NaOH (aq), pH 13-14

  Na₂O (s) + H₂O (l) > 2NaOH (aq)

Reaction with acid forming salt and water

Na₂O (s) + 2H⁺ > 2Na⁺ (aq) + H₂O (l)

Properties of MgO (s)

MP/BP: High (Strong Ionic Bonds)

Acid/ base Nature: Basic

Reaction with water

• Sparingly soluble in water, reacts with water small extent to form limited quantity of Mg(OH)₂ (aq)

• weakly alkaline solution, pH 9

  MgO (s) + H₂O (l) = Mg²⁺ (aq) + 2OH^- (aq)

Reaction with acid forming salt and water

MgO (s) + 2H⁺ > Mg²⁺ (aq) + H₂O (l)

Properties of Al₂O₃ (s)

MP/BP: High (Strong Ionic bonds)

Acid/ base Nature: Amphoteric

Reaction with water

• Insoluble, due to high magnitude of lattice energy.

• Hydration energy from ion-dipole interaction is insufficient to overcome strong ionic bonds between oppositely charged ions

• neutral, pH 7

Reaction with Acid

Al₂O₃ (s) + 6H⁺ > 2Al³⁺ (aq) + 3H₂O (l)

Reaction with Alkali

Al₂O₃ (s) + 2OH^- (aq) + 3H₂O (l) > 2[Al(OH)₄]^-

Properties of SiO₂ (s)

MP/BP: High (Strong Covalent bonds)

Acid/ base Nature: Acidic

Reaction with water

• Insoluble, many strong Si-O covalent bonds; require large amount of energy to break

• neutral, pH 7

Reaction with Alkali

SiO₂ (s) + 2OH^- (aq) > SiO₃ ^2- (aq) + H₂O (l)

Properties of P₄O₆ (s) , P₄O₁₀ (s)

MP/BP: 6Low (Strong covalent bond within molecules, weak intermolecular forces between molecules)

Acid/ base Nature: Acidic

Reaction with water

• acidic, pH 2

P₄O₆ (s) + 6H₂O (l) > 4H₃PO₃ (aq) [phosphorous acid]

P₄O₁₀ (s) + 6H₂O (l) > 4H₃PO₄ (aq) [phosphoric acid]

Reaction with Alkali

P₄O₆ (s) + 8OH^- (aq) > 4HPO₃^2- (aq) + 2H₂O (l)

P₄O₁₀ (s) + 12OH^- (aq) > 4PO₄^3- (aq) + 6H₂O (l)

Properties of SO₂ (g) and SO₃ (l)

MP/BP: Low (Strong covalent bond within molecules, weak intermolecular forces between molecules)

Acid/ base Nature: Acidic

Reaction with water

• acidic solutions

SO₂ (g) + H₂O (l) > H₂SO₃ (aq) [sulfurous acid]

SO₃ (l) + H₂O (l) > H₂SO₄ (aq) [sulfuric acid]

Reaction with Alkali

SO₂ (g) + 2OH^- (aq) > SO₃^2- (aq) + H₂O (l)

SO₃ (l) + 2OH^- (aq) > SO₄^2- (aq) + H₂O (l)

Properties of NaOH (s)

Structure: Giant ionic, strong ionic bonds

Acid/ base Nature: Basic

Reaction with water

• Dissolves readily in water to give a strongly alkaline solution

• pH 13-14

NaOH (aq) > Na⁺ (aq) + OH^- (aq)

Reacts with acid

NaOH (s) + H⁺ (aq) > Na⁺ (aq) + H₂O (l)

Properties of Mg(OH)₂ (s)

Structure: Giant ionic, strong ionic bonds

Acid/ base Nature: Basic

Reaction with water

• Only slightly soluble in water

• weakly alkaline solution, pH 9

  Mg(OH)₂ (s) = Mg²⁺ (aq) + 2OH^- (aq)

Reacts with acid

Mg(OH)₂ (s) + 2H⁺ (aq) > Mg²⁺ (aq) + 2H₂O (l)

Properties of Al(OH)₃ (s)

Structure: Giant Ionic (Ionic bonds with covalent character)

• Al³⁺ has high charge density able to distort electron cloud of the ions

Acid/ base Nature: Amphoteric

Reaction with water

• Insoluble, strong ionic bonds betw oppositely charged ions

• neutral solution, pH 7

Reacts with acid

Al(OH)₃ (s) + 3H⁺ (aq) > Al³⁺ (aq) + 3H₂O (l)

Reacts with alkali

Al(OH)₃ (s) + OH^- (aq) > [Al(OH)₄]^- (aq)

Properties of Si(OH)₄ (s) / SiO₂•H₂O (s)

Structure: Giant covalent (Strong covalent bonds between Si and O atoms)

Acid/ base Nature: Acidic

Reaction with water

• Insoluble, strong covalent bonds between Si and O atoms

• neutral, pH 7

Reacts with hot concentrated alkali (DILUTED cannot)

SiO₂ (s) + 2OH^- (aq) > SiO₃^2- (aq) + H₂O (l)

Properties of NaCl (s)

Structure: Giant Ionic (Strong Ionic bonds)

MP/BP: High

Reaction with water

• Dissolves in water (hydration) to give neutral solutions

• No hydrolysis

  NaCl (s) + aq > Na⁺ (aq) + Cl^- (aq)

• ~pH 7

Properties of MgCl₂ (s)

Structure: Giant Ionic (Strong Ionic bonds)

MP/BP: High

Reaction with water

• Dissolves in water [Mg(H₂O)₆]²⁺ , which hydrolyses slightly (due to slightly higher charge)

• slightly acidic solution

• ~pH 6.5

  1) Hydration

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

  2) Hydrolysis

  [Mg(H₂O)₆]²⁺ (aq) = [Mg(H₂O)₅(OH)]⁺ (aq) + H⁺ (aq)

Properties of AlCl₃

Structure: Simple molecular (Covalent bonds with ionic character)

MP/BP: Low

Reaction with water

• Dissolves in water [Al(H₂O)₆]³⁺ , which hydrolyses (due to high charge density)

• acidic solution

• ~pH 3

  1) Hydration

  AlCl₃ (s) + 6H₂O (l) > [Al(H₂O)₆]³⁺ (aq) + 3Cl^- (aq)

  2) Hydrolysis

  [Al(H₂O)₆]³⁺ (aq) = [Al(H₂O)₅(OH)]²⁺ (aq) + H⁺ (aq)

Effect adding small qty of water

• White fumes HCl observed

• AlCl₃ (s) + 3H₂O (l) > Al(OH)₃ (aq) + 3HCl (g)

Properties of SiCl₄ (l)

Structure: Simple Molecular (Strong covalent bonds within molecules AND weak intermolecular forces of attraction between molecules)

MP/BP: Low

Reaction with water

• Covalent chlorides hydrolyses completely in water

• acidic solution due to formation of HCl

• Central atom of the chloride has low-lying vacant 3d orbitals to form dative covalent bonds with water molecules

• By accepting the lone pair of electrons on O of H₂O to form an unstable transition state, breaking down to form HCl

• ~pH 2

• White fumes HCl observed

  Hydrolysis

  SiCl₄ (l) + 2H₂O (l) > SiO₂ (s) + 4HCl (aq)
  OR

  SiCl₄ (l) + 4H₂O (l) > SiO₂•H₂O (s) + 4HCl (aq)

Effect adding small qty of water

• White fumes HCl observed

• SiCl₄ (l) + 2H₂O (l) > SiO₂ (s) + 4HCl (g)

Properties of PCl₅ (s) , PCl₃ (l)

Structure: Simple Molecular (Strong covalent bonds within molecules AND weak intermolecular forces of attraction between molecules

MP/BP: Low

Reaction with water

• Covalent chlorides hydrolyses completely in water

• acidic due to the formation of HCl

• Central atom of the chloride has low-lying vacant 3d orbitals to form dative bonds with H₂O molecules

• By accepting lone pair of electrons on O of H₂O to form an unstable transition state, breaking down to form HCl

• ~pH 1-2

• White fumes HCl observed

Hot excess water:

PCl₅ (s) + 4H₂O (l) > H₃PO₄ (s) + 5HCl (aq)

Cold excess water:

PCl₅ (s) + H₂O (l) > POCl₃ (s) + 2HCl (aq)

PCl₃ (l) + 3H₂O (l) > H₃PO₃ (s) + 3HCl (aq)

Effect of adding small qty of water

• White fumes of HCl observed

• PCl₅ (s) + H₂O (l) > POCl₃ (l) + 2HCl (aq)

Factors affecting thermal stability of G2 carbonates and nitrates

a) Polarising power of M²⁺ cation

• The larger the charge density of the metal cation

• Stronger the polarising power

• Lower the thermal stability

b) Polarisability of anion

• The larger the size of the anoin

• Greater its polarisability

• Lower the thermal stability

Thermal stability down the group

• Since radius of M²⁺ increases down the group

• the charge density of M²⁺ decreases

• Hence the ability for M²⁺ to polarise the large anion decreases

• and the bond in the anion is weakened to a smaller extent

• Thus thermal stability increases down the group