GROUP 3 OXIDES

Na 2 O MgO Al 2 O 3 SiO 2 P 4 O 10 SO 3 Cl 2 O 7 – highest (oxidation number) oxides P 4 O 6 SO 2 Cl 2 O Electronegativity increases

Ionic metallic oxides similar in shape to NaCl(s): Giant ionic (book p.27)

Structures of non-metallic oxides SiO 2 : giant covalent m.p. 1700 o C P 4 O 6 : molecular P 4 O 10 : molecular m.p. 24 o C, b.p. 173 o C sublimes 300 o C

chlorine (I) oxide chlorine(VII) oxide

Reaction of oxides with water:

Na 2 O(s) + H 2 O(l) 2Na(OH)(aq) MgO(s) + H 2 O(l) Mg(OH) 2 (aq) P 4 O 10 (s) + 6H 2 O 4H 3 PO 4 (aq) P 4 O 6 (s) + 6H 2 O 4H 3 PO 3 (aq) SO 3 (l) + H 2 O(l) H 2 SO 4 (aq) SO 2 (g) + H 2 O(l) H 2 SO 3 (aq) Cl 2 O 7 + H 2 0 2HClO 4 (aq) Cl 2 O(aq) + H 2 O(l) HOCl(aq) [Chlorine(I) oxide less acidic than chlorine(VII) oxide]

Reaction of oxides with bases

Al 2 O 3 (s) + 2NaOH(aq) + 3H 2 O(l) 2NaAl(OH) 4 (aq) SiO 2 (s) + 2NaOH(aq) Na 2 SiO 3 (aq) + H 2 O(l) Phosphorous oxides form acids which are neutralized by base SO 2 (g) + NaOH(aq) Na 2 SO 3 (aq) + H 2 0(l) Cl 2 O 7 (g) + NaOH(aq) 2NaClO 4 (aq) + H 2 O(l) Cl 2 O(g) + NaOH(aq) 2NaClO(aq) + H 2 O(l)

Reaction of amphoteric oxide with acids

Al 2 O 3 (s) + 6HCl(aq) 2AlCl 3 (aq) + H 2 0(l) [AlCl 3 (s) itself reacts with water/aqueous solution to form Al(OH) 3 + H + 3Cl (aq)] (aq)+

Hydroxides (Al to Cl) Al(OH) 3 (s) + HCl(aq) AlCl 3 (aq) + 3H 2 O(l) Al(OH) 3 (s) + NaOH(aq) NaAl(OH) 4 (aq)

phosphoric(III) acid

These react like acids!

HO-Cl chloric(I) acid