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Periodic Relationship among the Oxides, Chlorides and Simple Hydrides of the Elements Li to Cl

Chapter 40. Periodic Relationship among the Oxides, Chlorides and Simple Hydrides of the Elements Li to Cl. 40.1 O xides 40.2 Chlorides 40.3 Simple Hydrides 40.4 Periodicity in Stoichiometric Composition of Oxides, Chlorides and Hydrides of Periods 2 and 3 Elements.

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Periodic Relationship among the Oxides, Chlorides and Simple Hydrides of the Elements Li to Cl

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  1. Chapter 40 Periodic Relationship among the Oxides, Chlorides and Simple Hydrides of the Elements Li to Cl 40.1 Oxides 40.2Chlorides 40.3Simple Hydrides 40.4Periodicity in Stoichiometric Composition of Oxides, Chlorides and Hydrides of Periods 2 and 3 Elements

  2. 40.1 Oxides (SB p.17) Periodicity in Nature of Bonding of Oxides The oxides of Periods 2 and 3 elements can be grouped into 3 types according to the nature of their bonding: 1. Ionic oxides; 2. Ionic oxides with high covalent character; 3. Covalent oxides

  3. 40.1 Oxides (SB p.18) Periodicity in nature of bonding in the oxides of Periods 2 and 3 elements

  4. 40.1 Oxides (SB p.18) Periodicity in the Behaviour of Oxides in Water Ionic Oxides Li2O(s) + H2O(l)  2LiOH(aq) Na2O(s) + H2O(l)  2NaOH(aq) Na2O2(s) + 2H2O(l)  2NaOH(aq) + H2O2(aq) MgO(s) + H2O(l)  Mg(OH)2(aq) MgO is less basic as Mg(OH)2 is slightly soluble in water. Only a weakly alkaline solution formed.

  5. BeO(s) + 2OH–(aq) + H2O(l)  [Be(OH)4]2–(aq) beryllate ion Al2O3(s) + 2OH–(aq) + 3H2O(l)  2[Al(OH)4]–(aq) aluminate ion 40.1 Oxides (SB p.19) Ionic Oxides with High Covalent Character BeO and Al2O3 are amphoteric, and react with both acids and bases. Both are insoluble in water. BeO(s) + 2H+(aq)  Be2+(aq) + H2O(l) Al2O3(s) + 6H+(aq)  2Al3+(aq) + 3H2O(l)

  6. CO2(g) + H2O(l) H2CO3(aq) carbonic acid 40.1 Oxides (SB p.19) Covalent Oxides Behaviour of Covalent Oxides of Elements in Period 2 in Water B2O3(s) + 3H2O(l)  2H3BO3(s) boric(III) acid Carbon monoxide is neutral and insoluble in water.

  7. 40.1 Oxides (SB p.19) Dinitrogen oxide and nitrogen oxide are neutral and insoluble in water. 2NO2(g) + H2O(l)  HNO2(aq) + HNO3(aq) cold nitric(III) nitric(V) acid acid N2O4(g) + H2O(l)  HNO2(aq) + HNO3(aq)

  8. 40.1 Oxides (SB p.20) N2O5(s) + H2O(l)  2HNO3(aq) cold nitric(V) acid Oxygen is neutral and very slightly soluble in water. Oxygen difluoride is a colourless gas which hydrolyzes slowly to form oxygen and hydrogen fluoride OF2(g) + H2O(l)  2HF(aq) + O2(g)

  9. 40.1 Oxides (SB p.19) Behaviour of Covalent Oxides of Elements in Period 3 in Water SiO2(s)does not react with water. It is slightly acidic, and reacts with boiling alkalis to form silicates(IV) SiO2(s) + 2NaOH(aq)  Na2SiO3(aq) + H2O(l)

  10. 40.1 Oxides (SB p.20) P4O6 reacts slowly 2P4O6(s) + 6H2O(l)  4H3PO3(aq) cold phosphoric(III) acid P4O10 reacts vigorously 2P4O10(s) + 2H2O(l)  4HPO3(aq) cold polyphosphoric(V) acid 2P4O10(s) + 6H2O(l)  4H3PO4(aq) warm phosphoric(V) acid

  11. SO2(g) + H2O(l) H2SO3(aq) sulphuric(IV) acid SO3(g) + H2O(l) H2SO3(aq) sulphuric(VI) acid 40.1 Oxides (SB p.20) Cl2O(g) + H2O(l)  2HOCl(aq) chloric(I) acid Cl2O7(g) + H2O(l)  2HClO4(aq) chloric(VII) acid (very strong acid)

  12. 40.1 Oxides (SB p.21)

  13. 40.1 Oxides (SB p.21)

  14. (a) SiO2 does not react with water because the electronegativity values of silicon and oxygen are very similar, and the Si – O bond can be considered as non-polar. As a result, there is no positive centre for the lone pair electrons of the water molecule to attack. 40.1 Oxides (SB p.22) Check Point 40-1 (a) Why does SiO2 not react with water? Answer

  15. (b) (i) K2O(s) + H2O(l)  2KOH(aq) (ii) BaO(s) + H2O(l)  Ba(OH)2(s) (iii) Al2O3(s) + 3H2SO4(aq)  Al2(SO4)3(aq) + 3H2O(l) 40.1 Oxides (SB p.22) Check Point 40-1 (b) Complete and balance the following equations. (i) K2O(s) + H2O(l)  (ii) BaO(s) + H2O(l)  (iii) Al2O3(s) + H2SO4(aq)  Answer

  16. 40.2 Chlorides (SB p.22) Periodicity in Nature of Bonding of Chlorides The chlorides of Period 2 and 3 elements can be grouped into 3 types according to the nature of their bonding: 1. Ionic chlorides; 2. Ionic chlorides with high covalent character; 3. Covalent chlorides

  17. 40.2 Chlorides (SB p.22) Periodicity in nature of bonding in the chlorides of Periods 2 and 3 elements

  18. H2O LiCl(s)  Li+(aq) + Cl–(aq) H2O NaCl(s)  Na+(aq) + Cl–(aq) LiCl and NaCl dissolve in water but do not react with it MgCl2(s) + H2O(l) Mg(OH)Cl(s) + HCl(aq) MgCl2 hydrolyzes slightly in water MgCl2· 6H2O(s)  Mg(OH)Cl(s) + HCl(g) + 5H2O(l) The hydrated crystal gives off HCl and leaves a basic salt when heated during hydrolysis  40.2 Chlorides (SB p.23) Periodicity in the Behaviour of Chlorides in Water Ionic Chlorides

  19. AlCl3 hydrolyzes reversibly in water. AlCl3(s) + 6H2O(l) [Al(H2O)6]3+(aq) + 3Cl–(aq) 40.2 Chlorides (SB p.23) Ionic Chlorides with High Covalent Character BeCl2 dissolves in water forming hydrated [Be(H2O)4]2+ species. This species hydrolyzes extensively in water. [Be(H2O)4]2+(aq) + H2O(l)  [Be(H2O)3(OH)]+(aq) + H3O+(aq)

  20. The hydrated aluminium ion will further dissociate to give an acidic solution. This is known as cation hydrolysis. [Al(H2O)6]3+(aq) + H2O(l) [Al(H2O)5(OH)]2+(aq) + H3O+(aq) [Al(H2O)5(OH)]2+(aq) + H2O(l)[Al(H2O)4(OH)2] +(aq) + H3O+(aq) [Al(H2O)4(OH)2] +(aq) + H2O(l)[Al(H2O)3(OH)3](aq) + H3O+(aq) 40.2 Chlorides (SB p.23)

  21. 40.2 Chlorides (SB p.24) Covalent Chlorides Behaviour of Covalent Chlorides of Elements in Period 2 in Water BCl3(l) + 3H2O(l)  H3BO3(aq) + 3HCl(aq) boric(III) acid Tetrachloromethane is a non-polar molecule and immiscible with water. Also, carbon has no vacant d-orbitals. It does not react with water. NCl3(l) + H2O(l)  NH3(aq) + 3HOCl(aq) ammonia chloric(I) acid

  22. 40.2 Chlorides (SB p.24) Cl2O(g) + H2O(l)  2HOCl(aq) chloric(I) acid Chlorine fluoride undergoes hydrolysis in water, forming hydrogen fluoride and chloric(I) acid ClF(g) + H2O(l)  HF(aq) + HOCl(aq) hydrogen chloric(I) acid fluoride

  23. 40.2 Chlorides (SB p.24) Behaviour of Covalent Chlorides of Elements in Period 3 in Water Silicon(IV) chloride undergoes complete hydrolysis in water SiCl4(l) + 4H2O(l)  SiO2· 2H2O(s) + 4HCl(aq) PCl3(l) + 3H2O(l)  H3PO3(aq) + 3HCl(aq) coldphosphoric(III) acid PCl5 reacts with water vigorously to form phosphorus oxychloride and is then hydrolyzed to phosphoric(V) acid

  24. 40.2 Chloride (SB p.24) PCl5(s) + H2O(l)  POCl3(l) + 2HCl(aq)phosphorus oxychloride POCl3(l) + 3H2O(l)  H3PO4(aq) + 3HCl(aq)phosphoric(V) acid Sulphur dichloride and disulphur dichloride undergo hydrolysis in water SCl2(l) + H2O(l)  HSCl(aq) + HOCl(aq) S2Cl2(s) + 2H2O(l)  4HCl(aq) + SO2(g) + 3S(s) Chlorine undergoes hydrolysis in water to form an acidic solution Cl2(g) + H2O(l)  HCl(aq) + HOCl(aq)

  25. 40.1 Chlorides (SB p.25)

  26. 40.2 Chlorides (SB p.25)

  27. (a) AlCl3(s) + 6H2O(l)  [Al(H2O)6]3+(aq) + 3Cl-(aq) [Al(H2O)6]3+(aq) + H2O(l) [Al(H2O)5(OH)]2+(aq) + H3O+(aq) (b) Cl2O6(g) + H2O(l) HClO3(aq) + HClO4(aq) 40.2 Chlorides (SB p.25) Check Point 40-2 Give the equation for the reaction between each of the following compounds and water. (a) AlCl3 (b) Cl2O6 Answer

  28. 40.3 Simple Hydrides (SB p.26) Periodicity in Nature of Bonding of Simple Hydrides The hydrides of Period 2 and 3 elements can be grouped into 3 types according to the nature of their bonding: 1. Ionic hydrides; 2. Covalent hydrides with some ionic character; 3. Typical covalent hydrides; 4. Polar covalent hydrides

  29. 40.3 Simple Hydrides (SB p.26) Periodicity in nature of bonding in the hydrides of Periods 2 and 3 elements

  30. 40.3 Simple Hydrides (SB p.27) Periodicity in the Behaviour of Hydrides in Water Ionic Hydrides LiH(s) + H2O(l)  LiOH(aq) + H2(g) NaH(s) + H2O(l)  NaOH(aq) + H2(g) LiH and NaH react with water to form an alkaline solution with the evolution of hydrogen gas.

  31. 40.3 Simple Hydrides (SB p.27) Covalent Hydrides with some Ionic Character BeH2(s) + 2H2O(l)  Be(OH)2(s) + 2H2(g) MgH2(s) + 2H2O(l)  Mg(OH)2(s) + 2H2(g) The solution formed is less alkaline as Be(OH)2 and Mg(OH)2 are slightly soluble in water B2H6(g) + 6H2O(l)  H3BO3(aq) + 6H2(g) AlH3(s) + 3H2O(l)  Al(OH)3(aq) + 3H2(g) B2H6 is hydrolyzed to formboric acid while AlH3 is hydrolyzed to give a slightly alkaline solution

  32. 40.3 Simple Hydrides (SB p.27) Typical Covalent Hydrides Methane is immiscible with water and has no reaction with water SiH4(g) + 4H2O(l)  SiO2• 2H2O(s) + 4H2(g) Silane dissolves in water and is hydrolyzed slowly Phosphine is slightly basic and has no reaction with water

  33. NH3(g) + H2O(l) NH4+(aq) + OH–(aq) Ammonia is a weak base HF(g) + H2O(l) H3O+(aq) + F–(aq) Hydrogen fluoride is a weak acid 40.3 Simple Hydrides (SB p.27) Polar Covalent Hydrides Behaviour of Polar Covalent Hydrides of Elements in Period 2 in Water

  34. H2S(g) + H2O(l) H3O+(aq) + HS–(aq) H2O(l) H3O+(aq) + S2–(aq) H2S forms a weak acid 40.3 Simple Hydrides (SB p.28) Behaviour of Polar Covalent Hydrides of Elements in Period 3 in Water HCl(g) + H2O(l)  H3O+(aq) + Cl–(aq) HCl is very soluble in water and is a strong acid

  35. 40.3 Simple Hydrides (SB p.28)

  36. 40.3 Simple Hydrides (SB p.28)

  37. (a) (i) (1) NH3 reacts with water to give an alkaline solution. NH3(g) + H2O(l) NH4+(aq) + OH–(aq) (2) HCl reacts with water to form an acidic solution HCl(g) + H2O(l)  H3O+(aq) + Cl–(aq) 40.3 Simple Hydrides (SB p.29) Check Point 40-3 (a) (i) Describe the reaction of each of the following hydrides with water. Write appropriate equations. (1) NH3 (2) HCl Answer

  38. (a) (ii) The reason why the above two hydrides react differently with water is that ammonia molecule makes use of the lone pair electrons on the nitrogen atom to abstract the H+ from a water molecule, leaving OH– ion. On the contrary, the hydrogen atom in the HCl molecule carries a partial positive charge, so it is abstracted by the lone pair electrons of the water molecule,thus forming hydroxonium ion. 40.3 Simple Hydrides (SB p.29) Check Point 40-3 (a) (ii) Explain why the above two hydrides react differently with water. Answer

  39. (b) CH4 does not react with water because the carbon atom of the molecule does not have lone pair electrons. Also, as the electronegativity values of carbon and hydrogen are very similar, the polarity of C – H bond is very small. Therefore, the hydrogen atom of CH4 molecule cannot be abstracted by the lone pair electrons of thewater molecule. 40.3 Simple Hydrides (SB p.29) Check Point 40-3 (b) Explain why CH4 does not react with water. Answer

  40. 40.4 Periodicity in Stoichiometric Composition of Oxides, Chlorides and Hydrides of Period 2 and 3 Elements (SB p.29) Periodicity in stoichiometric composition of the oxides, chlorides and hydroxides of Period 2 elements

  41. 40.4 Periodicity in Stoichiometric Composition of Oxides, Chlorides and Hydrides of Period 2 and 3 Elements (SB p.29) Periodicity in stoichiometric composition of the oxides, chlorides and hydroxides of Period 3 elements

  42. 40.4 Periodicity in Stoichiometric Composition of Oxides, Chlorides and Hydrides of Period 2 and 3 Elements (SB p.30) Observations: • Across the period, number of oxygen, chlorine or hydrogen atom that combine with each atom of element increases. • Reach the maximum at Group IVA • Follow by decrease and reach the minimum at Group VIIA • P, S and Cl have a wide range of oxidation states • ∵ able to expand their octets by utilizing vacant 3d orbitals for bonding

  43. 40.4 Periodicity in Stoichiometric Composition of Oxides, Chlorides and Hydrides of Period 2 and 3 Elements (SB p.30) • P, S and Cl show their highest oxidation states in oxides or chloride but not hydrides • ∵ oxygen and chlorine are much electronegative than hydrogen

  44. The END

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