period 3 oxides - trends and reactions w/ water

describe and explain the overall trend in the mpts of the period 3 oxides from Na₂O → Al₂O₃:

• increase, decrease (respectively)

• overall: high mpts as form giant ionic lattices - strong forces of attraction require a large amount of E to overcome

how and why does the mpt change from Na₂O to MgO?

• increase

• Mg is smaller and has a bigger charge and so a greater charge density

how and why does the mpt change from MgO to Al₂O₃?

• decrease

• smaller electronegativity diff between Al and O than Mg and O

• so oxygen ions in Al₂O₃ don’t attract e^- in the metal-oxygen bond as strongly as in MgO

• so Al₂O₃ bonds are partially covalent

how and why does the mpt change when you reach SiO₂?

• decrease - but still higher compared to other non metal oxides

• as has a giant covalent structure with strong covalent bonds which require a large amount of energy to break

describe and explain the overall trend in the mpts of the period 3 oxides from P₄O₁₀ → SO₂:

• decrease, decrease (respectively)

• low mpts as are simple molecular structures - weak IMF: DPDP and VDWs which require little energy to overcome

how do Na₂O and MgO react with water? refer to the ions and state the ionic eqn:

• dissolve in water

• O^2- ions react with water to form OH^-, forming alkaline solutions

• O^2- + H₂O → 2OH^-

give the eqn for Na₂O reacting with water:

Na₂O _(s) + H₂O _(l) → 2NaOH _(aq)

give the eqn for MgO reacting with water and state the additional observation:

MgO _(s) + H₂O _(l) → Mg(OH)_{2 (aq)} - bright white flame

are Na₂O and MgO acidic, amphoteric or basic oxides? why?

basic - react with acids (to form bases)

which 2 group 3 oxides are insoluble in water and why?

• Al₂O₃ and SiO₂

• dessicants - absorb water into structure

is SiO₂ basic, acidic, or amphoteric? what does this mean?

acidic - reacts with bases (to form acids)

are sulfur oxides acidic, basic or amphoteric? what does this mean?

acidic - react with bases (to form acids)

give the eqn for the reaction of phosphorous oxide with water:

P₄O_{10 (s)} + 6H₂O _(l) → 4H₃PO_{4 (aq)}

give the eqn for the reaction of sulphur dioxide with water and name the product:

SO_{2 (g)} + H₂O _(l) → H₂SO_{3 (aq)} - sulphurous acid

give the eqn for the reaction of sulfur trioxide with water and name the product:

SO_{3 (g)} + H₂O _(l) → H₂SO_{4 (aq)} - sulphuric acid

is silicon dioxide soluble in water? is it acidic, basic or amphoteric?

• insoluble

• acidic - reacts with bases (to form acids)

is aluminium oxide water soluble? is it acidic, basic or amphoteric?

• insoluble

• amphoteric - reacts with both acids and bases

give the formula and structure of the phosphate (V) ion:

give the formula and structure of the sulfite (IV) ion:

give the formula and structure of the sulfate (VI) ion:

give the formula and structure of sulfuric acid:

H₂SO₄

give the formula and structure of sulfuruous acid:

H₂SO₃

give the formula and structure of phosphoric acid:

H₃PO₄

give the formula of a hydroxide of an element in period 3 used in medicine:

Mg(OH)₂