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39. Periodic Relationship among the Oxides of the Elements Li to Cl. 39.1 Bonding of the Oxides of Periods 2 and 3 Elements 39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis. 39.1. Bonding of the Oxides of Periods 2 and 3 Elements.
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39 Periodic Relationship among the Oxides of the Elements Li to Cl 39.1 Bonding of the Oxides of Periods 2 and 3 Elements 39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis
39.1 Bonding of the Oxides of Periods 2 and 3 Elements
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.19) Introduction • The electronegativity value of oxygen is 3.5
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.19) Introduction • When oxygen combines with elements having low electronegativity values (e.g. metals) • the oxygen atoms would gain the electrons from the elements • to form oxide ions
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.19) Introduction • The compounds formed consist of • positive ions formed the electropositive elements • negative oxide ions • These oxides are ionic oxides
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.19) Introduction • When oxygen combines with elements of similar electronegativity values • the oxygen atoms would share electrons with these elements • to form covalent oxides
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.19) Nature of Bonding • The oxides of Periods 2 and 3 elements can be classified into • ionic oxides • ionic oxides with high covalent character • covalent oxides
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.20) Periodicity in nature of bonding of the oxides of Periods 2 and 3 elements
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.20) Nature of Bonding • Going across a period from left to right, the nature of bonding of the oxides changes from • ionic bonding • ionic bonding with covalent character • covalent bonding
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.20) Nature of Bonding • A number of elements in Periods 2 and 3 form more than one oxide with oxygen • Example: • Sodium is a reactive metal • can form the normal oxide and peroxide with oxygen
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.20) Nature of Bonding • Elements with electronegativity values similar to oxygen also form a variety of oxides
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.20) Names, stoichiometric composition and electronic structures of oxides of Periods 2 and 3 elements
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.20 – 21 ) Names, stoichiometric composition and electronic structures of oxides of Periods 2 and 3 elements
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.21) Names, stoichiometric composition and electronic structures of oxides of Periods 2 and 3 elements
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.21) Names, stoichiometric composition and electronic structures of oxides of Periods 2 and 3 elements
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.21) Names, stoichiometric composition and electronic structures of oxides of Periods 2 and 3 elements
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.22) Names, stoichiometric composition and electronic structures of oxides of Periods 2 and 3 elements
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.22) Names, stoichiometric composition and electronic structures of oxides of Periods 2 and 3 elements
Check Point 39-1 39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.22) Names, stoichiometric composition and electronic structures of oxides of Periods 2 and 3 elements
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23) Ionic Oxides • Generally react with water to form hydroxides • As hydroxides are basic oxides • they neutralize with dilute acids to form salts • Do not react with dilute alkalis
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23) Ionic Oxides • Lithium oxide • reacts vigorously with water to form lithium hydroxide • Li2O(s) + H2O(l) 2LiOH(aq)
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23) Ionic Oxides • Sodium monoxide • reacts vigorously with water to form sodium hydroxide • Na2O(s) + H2O(l) 2NaOH(aq)
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23) Ionic Oxides • Sodium peroxide • reacts with water to give sodium hydroxide and hydrogen peroxide • Na2O2(s) + 2H2O(l) 2NaOH(aq) + H2O2(aq)
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23) Ionic Oxides • Magnesium oxide • less basic • reacts slightly with cold water and moderately with hot water to form magnesium hydroxide, which is very slightly soluble
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23) Ionic Oxides • Magnesium oxide • Magnesium hydroxide solution is a weakly alkaline solution • MgO(s) + H2O(l) Mg(OH)2(s)
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23) Ionic Oxides • All ionic oxides react with dilute acids to form salts
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23) Ionic Oxides • The reactions can be summarized by the following ionic equations: • Li2O(s) + 2H+(aq) 2Li+(aq) + H2O(l) • Na2O(s) + 2H+(aq) 2Na+(aq) + H2O(l) • Na2O2(s) + 2H+(aq) 2Na+(aq) + H2O2(aq) • MgO(s) + 2H+(aq) Mg2+(aq) + H2O(l)
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23) Ionic Oxides with High Covalent Character • Beryllium oxide and aluminium oxide • ionic oxides with high covalent character • not soluble in water
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23) Ionic Oxides with High Covalent Character • Beryllium oxide and aluminium oxide • react with both dilute acids and dilute alkalis to form soluble compounds • amphoteric oxides
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23) Ionic Oxides with High Covalent Character • Beryllium oxide and aluminium oxide • BeO(s) + 2H+(aq) Be2+(aq) + H2O(l) • BeO(s) + 2OH–(aq) + H2O(l) [Be(OH) 4]2–(aq) beryllate ion
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23) Ionic Oxides with High Covalent Character • Beryllium oxide and aluminium oxide • Al2O3(s) + 6H+(aq) 2Al3+(aq) + 3H2O(l) • Al2O3(s) + 2OH–(aq) + 3H2O(l) 2[Al(OH)4]–(aq) aluminate ion
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.24) Covalent Oxides • Some covalent oxides that are soluble in water • react with water to form acids • react with dilute alkalis • do not react with dilute acids
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.24) 1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalis • Boron(III) oxide • reacts with water to form boric(III) acid • B2O3(s) + 3H2O(l) 2H3BO3(s)
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.24) 1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalis • Carbon monoxide neutral insoluble in water
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.24) 1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalis • Carbon dioxide • moderately soluble in cold water • the solution formed is slightly acidic • CO2(g) + H2O(l) H2CO3(aq)
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.24) 1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalis • Dinitrogen oxide and nitrogen monoxide • neutral • insoluble in water
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.24) 1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalis • Nitrogen dioxide • reacts rapidly with cold water to give a mixture of nitric(III) acid and nitric(V) acid • 2NO2(g) + H2O(l) HNO2(aq) + HNO3(aq) nitric(III) acid nitric(V)acid
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.24) 1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalis • Dinitrogen tetraoxide • reacts with water to form nitric(III) acid and nitric(V) acid • N2O4(g) + H2O(l) HNO2(aq) + HNO3(aq)
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.24) 1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalis • Dinitrogen pentaoxide • reacts with cold water to form nitric(V) acid • N2O5(s) + H2O(l) 2HNO3(aq)
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.24) 1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalis • Oxygen • neutral • very slightly soluble in water
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.24) 1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalis • Oxygen difluoride • colourless gas • hydrolyzes slowly to form oxygen gas and hydrogen fluoride • OF2(g) + H2O(l) 2HF(aq) + O2(g)
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.24) 1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalis • The reactions can be summarized by the following ionic equations: • B2O3(s) + 6OH–(aq) 2BO33–(aq) + 3H2O(l) • CO2(g) + 2OH–(aq) CO32–(aq) + H2O(l)
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.24) 1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalis • The reactions can be summarized by the following ionic equations: • 2NO2(g) + 2OH–(aq) NO2–(aq) + NO3–(aq) + H2O(l) • N2O4(g) + 2OH–(aq) NO2–(aq) + NO3–(aq) + H2O(l)
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.24) 1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalis • The reactions can be summarized by the following ionic equations: • N2O5(s) + 2OH–(aq) 2NO3–(aq) + H2O(l) • OF2(g) + 2OH–(aq) 2F–(aq) + O2(g) + H2O(l)
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.25) 2. Behaviour of Covalent Oxides of Period 3 Elements in Water and Dilute Alkalis • Silicon(IV) oxide • does not react with water • weakly acidic • reacts with hot alkalis to form silicates(IV) • SiO2(s) + 2NaOH(aq) Na2SiO3(aq) + H2O(l)
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.25) 2. Behaviour of Covalent Oxides of Period 3 Elements in Water and Dilute Alkalis • Phosphorus(III) oxide • reacts slowly with cold water to form phosphoric(III) acid • P4O6(s) + 6H2O(l) 4H3PO3(aq)
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.25) 2. Behaviour of Covalent Oxides of Period 3 Elements in Water and Dilute Alkalis • Phosphorus(V) oxide • reacts vigorously with cold water to form phosphoric(V) acid • P4O10(s) + 6H2O(l) 4H3PO4(aq)
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.25) 2. Behaviour of Covalent Oxides of Period 3 Elements in Water and Dilute Alkalis • Sulphur dioxide • react with water to form sulphuric(IV) acid • SO2(g) + H2O(l) H2SO3(aq) sulphuric(IV) acid
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.25) 2. Behaviour of Covalent Oxides of Period 3 Elements in Water and Dilute Alkalis • Sulphur trioxide • react with water to form sulphuric(VI) acid • SO3(g) + H2O(l) H2SO4(aq) sulphuric(VI) acid