Periodic Relationship among the Oxides of the Elements Li to Cl 39 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

Bonding of the Oxides of Periods 2 and 3 Elements 39.1 Bonding of the Oxides of Periods 2 and 3 Elements

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 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

Introduction The compounds formed consist of 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 Oxide of Period 2 element Li2O BeO B2O3 CO CO2 N2O NO NO2 N2O4 N2O5 O2 O3 OF2 Nature of bonding in the oxides Ionic Ionic with covalent character Covalent Oxide of Period 3 element Na2O Na2O2 MgO Al2O3 SiO2 P4O6 P4O10 SO2 SO3 Cl2O Cl2O7

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 Element Name of oxide of element Stoichiometric composition of oxide of element Electronic structure of oxide of element Lithium Lithium oxide Li2O Beryllium Beryllium oxide BeO Boron Boron oxide B2O3

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 Element Name of oxide of element Stoichiometric composition of oxide of element Electronic structure of oxide of element Carbon Carbon monoxide CO Carbon dioxide CO2 Nitrogen Dinitrogen oxide N2O Nitrogen monoxide NO

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 Element Name of oxide of element Stoichiometric composition of oxide of element Electronic structure of oxide of element Nitrogen Nitrogen dioxide NO2 Dinitrogen tetraoxide N2O4 Dinitrogen pentaoxide N2O5

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 Element Name of oxide of element Stoichiometric composition of oxide of element Electronic structure of oxide of element Oxygen O2 Ozone O3 Fluorine Oxygen difluoride OF2 Sodium Sodium monoxide Na2O Sodium peroxide Na2O2

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 Element Name of oxide of element Stoichiometric composition of oxide of element Electronic structure of oxide of element Magnesium Magnesium oxide MgO Aluminium Aluminium oxide Al2O3 Silicon Silicon(IV) oxide SiO2

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 Element Name of oxide of element Stoichiometric composition of oxide of element Electronic structure of oxide of element Phosphorus Phosphorus(III) oxide P4O6 Phosphorus(V) oxide P4O10

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 Element Name of oxide of element Stoichiometric composition of oxide of element Electronic structure of oxide of element Sulphur Sulphur dioxide SO2 Sulphur trioxide SO3

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 Element Name of oxide of element Stoichiometric composition of oxide of element Electronic structure of oxide of element Chlorine Chlorine(I) oxide (dichlorine oxide) Cl2O Chlorine(VII) oxide (dichlorine heptaoxide) Cl2O7 Check Point 39-1

39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis

Ionic Oxides Generally react with water to form hydroxides 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

Ionic Oxides Lithium oxide 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)

Ionic Oxides Sodium monoxide 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)

Ionic Oxides Sodium peroxide 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)

Ionic Oxides Magnesium oxide  less basic 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

Ionic Oxides Magnesium oxide 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)

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 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)

Ionic Oxides with High Covalent Character 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

Ionic Oxides with High Covalent Character 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

Ionic Oxides with High Covalent Character 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

Ionic Oxides with High Covalent Character 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

Covalent Oxides Some covalent oxides that are soluble in water 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

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 Chlorine(I) oxide  dissolves in water to form chloric(I) acid (also known as hypochlorus acid) Cl2O(g) + H2O(l)  2HOCl(aq) chloric(I) 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 Chlorine(VII) oxide  dissolves in water to form a very strong acid called chloric(VII) acid (also known as perchloric acid) Cl2O7(l) + H2O(l)  2HClO4(aq) chloric(VII) 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 Ionic equations: P4O6(s) + 12OH–(aq)  4PO43–(aq) + 6H2O(l) P4O10(s) + 12OH–(aq)  4PO43–(aq) + 6H2O(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 Ionic equations: SO2(g) + 2OH–(aq)  SO32–(aq) + H2O(l) SO3(g) + 2OH–(aq)  SO42–(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 Ionic equations: Cl2O(g) + 2OH–(aq)  2OCl–(aq) + H2O(l) Cl2O7(l) + 2OH–(aq)  2ClO4–(aq) + H2O(l)

Oxide of Period 2 element Behaviour of oxides in water 39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.26) Periodicity in the behaviour of oxides of Periods 2 elements in water, dilute acids and dilute alkalis Oxide of Period 2 element Li2O BeO B2O3 CO CO2 N2O NO NO2 N2O4 N2O5 O2 OF2 Behaviour of oxides in water Reacts vigorously with water to form LiOH Does not react with water Reacts with water to form H3BO3, which is a very weak acid CO: Insoluble in water CO2: Moderately soluble in water to form H2CO3, which is a very weak acid N2O and NO: Insoluble in water NO2 and N2O4: React with water to form HNO2 and HNO3 N2O5: Reacts with cold water to form HNO3 Very slightly soluble in water, does not react with water Hydrolyzes slowly to form O2 and an acidic solution of HF

Oxide of Period 2 element Behaviour of oxides in dilute acids 39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.26) Periodicity in the behaviour of oxides of Periods 2 elements in water, dilute acids and dilute alkalis Oxide of Period 2 element Li2O BeO B2O3 CO CO2 N2O NO NO2 N2O4 N2O5 O2 OF2 Behaviour of oxides in dilute acids Reacts to form Li+ Reacts to form Be2+ Does not react with dilute acids Do not react with dilute acids

Oxide of Period 2 element Behaviour of oxides in alkalis 39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.26) Periodicity in the behaviour of oxides of Periods 2 elements in water, dilute acids and dilute alkalis Oxide of Period 2 element Li2O BeO B2O3 CO CO2 N2O NO NO2 N2O4 N2O5 O2 OF2 Behaviour of oxides in alkalis Does not react with dilute alkalis Reacts to form [Be(OH)4]2– Reacts to form BO33– CO: Does not react with dilute alkalis CO2: Reacts to form CO32– N2O and NO: Do not react with dilute alkalis NO2 and N2O4: React to form NO2– and NO3– N2O5: Reacts to form NO3– Reacts to form F– and O2

Oxide of Period 2 element Acidic/ basic nature of oxides 39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.26) Periodicity in the behaviour of oxides of Periods 2 elements in water, dilute acids and dilute alkalis Oxide of Period 2 element Li2O BeO B2O3 CO CO2 N2O NO NO2 N2O4 N2O5 O2 OF2 Acidic/ basic nature of oxides Alkaline Amphoteric Acidic Neutral

Oxide of Period 3 element Behaviour of oxides in water 39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.27) Periodicity in the behaviour of oxides of Periods 3 elements in water, dilute acids and dilute alkalis Oxide of Period 3 element Na2O Na2O2 MgO Al2O3 SiO2 P4O6 P4O10 SO2 SO3 Cl2O Cl2O7 Behaviour of oxides in water Na2O: Reacts vigorously with water to form NaOH Na2O2: Reacts with water to form NaOH and H2O2 Reacts slightly with cold water and moderately with hot water to form a weakly alkaline solution of Mg(OH)2 Does not react with water P4O6: Reacts slowly with cold water to form H3PO3 P4O10: Reacts vigorously with cold water to form H3PO4 SO2: Reacts with water to form H2SO3 SO3: Reacts with water to form H2SO4 Cl2O: Dissolves in water to form HOCl Cl2O7: Dissolves in water to form HClO4

Oxide of Period 3 element Behaviour of oxides in dilute acids 39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.27) Periodicity in the behaviour of oxides of Periods 3 elements in water, dilute acids and dilute alkalis Oxide of Period 3 element Na2O Na2O2 MgO Al2O3 SiO2 P4O6 P4O10 SO2 SO3 Cl2O Cl2O7 Behaviour of oxides in dilute acids React to form Na+ Reacts to form Mg2+ Reacts to form Al3+ Does not react with dilute acids Do not react with dilute acids

Oxide of Period 3 element Behaviour of oxides in dilute alkalis 39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.27) Periodicity in the behaviour of oxides of Periods 3 elements in water, dilute acids and dilute alkalis Oxide of Period 3 element Na2O Na2O2 MgO Al2O3 SiO2 P4O6 P4O10 SO2 SO3 Cl2O Cl2O7 Behaviour of oxides in dilute alkalis Do not react with dilute alkalis Does not react with dilute alkalis Reacts to form [Al(OH)4]– Reacts with hot alkalis to form SiO32– P4O6: Reacts slowly with cold water to form H3PO3 P4O10: Reacts vigorously with cold water to form H3PO4 SO2: Reacts to form SO32– SO3: Reacts to form SO42– Cl2O: Reacts to form OCl– Cl2O7: Reacts to form ClO4–

Oxide of Period 3 element Acidic/ basic nature of oxides 39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.27) Periodicity in the behaviour of oxides of Periods 3 elements in water, dilute acids and dilute alkalis Oxide of Period 3 element Na2O Na2O2 MgO Al2O3 SiO2 P4O6 P4O10 SO2 SO3 Cl2O Cl2O7 Acidic/ basic nature of oxides Alkaline Weakly acidic Amphoteric Acidic Neutral Check Point 39-2

The END

39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.22) Check Point 39-1 (a) To which type of oxide does each of the following oxides belong? (i) Magnesium oxide (ii) Nitrogen monoxide (iii) Silicon dioxide (iv) Aluminium oxide Answer (a) (i) Ionic oxide (ii) Covalent oxide (iii) Covalent oxide (iv) Ionic oxide with covalent character

39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.22) Check Point 39-1 (b) Carbon can form two oxides. Name the two oxides and draw their electronic structures. Answer (b) Carbon monoxide (CO): Carbon dioxide (CO2): Back

39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.27) Check Point 39-2 (a) Why does silicon(IV) oxide not react with water? (a) Silicon(IV) oxide does not react with water because the electronegativity values of silicon and oxygen are very similar. The Si — O bond can be considered as nonpolar, so there is no positive centre for the lone pair electrons of the water molecule to attack. Answer

39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.27) Check Point 39-2 (b) Complete and balance the following equations: (i) K2O(s) + H2O(l)  (ii) Na2O2(s) + HCl(aq)  (iii) Al2O3(s) + H2SO4(aq)  (iv) P4O10(s) + NaOH(aq)  (v) SO3(g) + NaOH(aq)  Answer

39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.27) (b) (i) K2O(s) + H2O(l)  2KOH(aq) (ii) Na2O2(s) + 2HCl(aq)  2NaCl(aq) + H2O2(aq) (iii) Al2O3(s) + 3H2SO4(aq)  Al2(SO4)3(aq) + 3H2O(l ) (iv) P4O10(s) + 12NaOH(aq)  4Na3PO4(aq) + 6H2O(l) (v) SO3(g) + 2NaOH(aq)  Na2SO4(aq) + H2O(l) Back