Periodic Relationship aPeriodic Relationship among the Oxides of the mong the Oxides of the
Elements Li to ClElements Li to Cl39.139.1 Bonding of the Oxides of Periods 2 and 3 Bonding of the Oxides of Periods 2 and 3
ElementsElements
39.239.2 Behaviour of Oxides of Periods 2 and 3 Behaviour of Oxides of Periods 2 and 3
Elements in Water, Dilute Acids and Elements in Water, Dilute Acids and Dilute ADilute A
lkalislkalis
3399
39.39.11Bonding of the Bonding of the
Oxides of Oxides of Periods 2 and Periods 2 and
3 Elements3 Elements
IntroductionIntroduction
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.19)
• The electronegativity value of oxygen is 3.5
IntroductionIntroduction
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.19)
• 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
IntroductionIntroduction
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.19)
• The compounds formed consist of
positive ions formed the electropositive elements
negative oxide ions
• These oxides are ionic oxides
IntroductionIntroduction
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.19)
• When oxygen combines with elements of similar electronegativity values
the oxygen atoms would share electrons with these elements
to form covalent oxides
Nature of BondingNature of Bonding
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.19)
• 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
Nature of
bonding in
the oxides
Ionic
Ionic with
covalent
character
Covalent
Nature of BondingNature 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 BondingNature 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 BondingNature 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)
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.20)Names, stoichiometric composition and electronic structures o
f oxides of Periods 2 and 3 elements
Element
Name of
oxide of
element
Stoichiometric c
omposition of ox
ide of element
Electronic structure
of oxide of element
LithiumLithium
oxideLi2O
BerylliumBeryllium
oxideBeO
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 c
omposition of ox
ide of element
Electronic structure
of oxide of element
Carbon
Carbon
monoxideCO
Carbon
dioxideCO2
Nitrogen
Dinitrogen o
xideN2O
Nitrogen
monoxideNO
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.21)Names, stoichiometric composition and electronic structures o
f oxides of Periods 2 and 3 elements
Element
Name of
oxide of
element
Stoichiometric c
omposition of ox
ide of element
Electronic structure
of oxide of element
Nitrogen
Nitrogen
dioxideNO2
Dinitrogen t
etraoxideN2O4
Dinitrogen p
entaoxideN2O5
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.21)Names, stoichiometric composition and electronic structures o
f oxides of Periods 2 and 3 elements
Element
Name of
oxide of
element
Stoichiometric c
omposition of ox
ide of element
Electronic structure
of oxide of element
Oxygen
Oxygen O2
Ozone O3
FluorineOxygen difl
uorideOF2
Sodium
Sodium
monoxide
Na2O
Sodium
peroxideNa2O2
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.21)Names, stoichiometric composition and electronic structures o
f oxides of Periods 2 and 3 elements
Element
Name of
oxide of
element
Stoichiometric c
omposition of ox
ide of element
Electronic structure
of oxide of element
MagnesiumMagnesium
oxide
MgO
AluminiumAluminium o
xide
Al2O3
SiliconSilicon(IV)
oxide
SiO2
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.22)Names, stoichiometric composition and electronic structures o
f oxides of Periods 2 and 3 elements
Element
Name of
oxide of
element
Stoichiometric c
omposition of ox
ide of element
Electronic structure
of oxide of element
Phosphorus
Phosphorus
(III) oxideP4O6
Phosphorus
(V) oxideP4O10
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 c
omposition of ox
ide of element
Electronic structure
of oxide of element
Sulphur
Sulphur dio
xide
SO2
Sulphur trio
xide
SO3
39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.22)
Check Point 39-1Check Point 39-1
Names, stoichiometric composition and electronic structures of oxides of Periods 2 and 3 elements
Element
Name of
oxide of
element
Stoichiometric c
omposition of ox
ide of element
Electronic structure
of oxide of element
Chlorine
Chlorine(I) o
xide
(dichlorine o
xide)
Cl2O
Chlorine(VI
I) oxide
(dichlorine h
eptaoxide)
Cl2O7
39.39.22Behaviour of Oxides of Behaviour of Oxides of
Periods 2 and 3 ElementPeriods 2 and 3 Elements in Water, Dilute Acids s in Water, Dilute Acids
and Dilute Alkalisand Dilute Alkalis
Ionic OxidesIonic Oxides
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23)
• 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 OxidesIonic Oxides
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23)
• Lithium oxide
reacts vigorously with water to form lithium hydroxide
Li2O(s) + H2O(l) 2LiOH(aq)
Ionic OxidesIonic Oxides
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23)
• Sodium monoxide
reacts vigorously with water to form sodium hydroxide
Na2O(s) + H2O(l) 2NaOH(aq)
Ionic OxidesIonic Oxides
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23)
• Sodium peroxide
reacts with water to give sodium hydroxide and hydrogen peroxide
Na2O2(s) + 2H2O(l) 2NaOH(aq) +
H2O2(aq)
Ionic OxidesIonic Oxides
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23)
• Magnesium oxide
less basic
reacts slightly with cold water and moderately with hot water to form
magnesium hydroxide, which is very slightly soluble
Ionic OxidesIonic Oxides
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23)
• Magnesium oxide
Magnesium hydroxide solution is a weakly alkaline solution
MgO(s) + H2O(l) Mg(OH)2(s)
Ionic OxidesIonic Oxides
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23)
• All ionic oxides react with dilute acids to form salts
Ionic OxidesIonic Oxides
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23)
• 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 Ionic Oxides with High Covalent CharacterCovalent Character
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23)
• Beryllium oxide and aluminium oxide
ionic oxides with high covalent character
not soluble in water
Ionic Oxides with High Ionic Oxides with High Covalent CharacterCovalent Character
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23)
• Beryllium oxide and aluminium oxide
react with both dilute acids and dilute alkalis to form soluble compounds
amphoteric oxides
Ionic Oxides with High Ionic Oxides with High Covalent CharacterCovalent Character
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23)
• Beryllium oxide and aluminium oxide
BeO(s) + 2H+(aq) Be2+(aq) + H2O(l)
BeO(s) + 2OH–(aq) + H2O(l) [Be(OH) 4]2–(a
q) beryllate ion
Ionic Oxides with High Ionic Oxides with High Covalent CharacterCovalent Character
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.23)
• 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 OxidesCovalent Oxides
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.24)
• 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 Perio1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalid 2 Elements in Water and Dilute Alkaliss• 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 Perio1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalid 2 Elements in Water and Dilute Alkaliss• 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 Perio1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalid 2 Elements in Water and Dilute Alkaliss• 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 Perio1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalid 2 Elements in Water and Dilute Alkaliss• 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 Perio1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalid 2 Elements in Water and Dilute Alkaliss• 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 Perio1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalid 2 Elements in Water and Dilute Alkaliss• Dinitrogen tetraoxide
reacts with water to form nitric(III) acid and nitric(V) acid
N2O4(g) + H2O(l) HNO2(aq) + HNO3(a
q)
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 Perio1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalid 2 Elements in Water and Dilute Alkaliss• 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 Perio1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalid 2 Elements in Water and Dilute Alkaliss• 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 Perio1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalid 2 Elements in Water and Dilute Alkaliss• 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 Perio1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalid 2 Elements in Water and Dilute Alkaliss• The reactions can be summarized by the following ionic equations:
B2O3(s) + 6OH–(aq) 2BO3
3–(aq) + 3H2O(l)
CO2(g) + 2OH–(aq) CO3
2–(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 Perio1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalid 2 Elements in Water and Dilute Alkaliss• 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 Perio1. Behaviour of Covalent Oxides of Period 2 Elements in Water and Dilute Alkalid 2 Elements in Water and Dilute Alkaliss• 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) + H2
O(l)
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.25)
2. 2. Behaviour of Covalent Oxides of PBehaviour of Covalent Oxides of Period 3 Elements in Water and Dilute Aleriod 3 Elements in Water and Dilute Alkaliskalis• 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. 2. Behaviour of Covalent Oxides of PBehaviour of Covalent Oxides of Period 3 Elements in Water and Dilute Aleriod 3 Elements in Water and Dilute Alkaliskalis• 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. 2. Behaviour of Covalent Oxides of PBehaviour of Covalent Oxides of Period 3 Elements in Water and Dilute Aleriod 3 Elements in Water and Dilute Alkaliskalis• 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. 2. Behaviour of Covalent Oxides of PBehaviour of Covalent Oxides of Period 3 Elements in Water and Dilute Aleriod 3 Elements in Water and Dilute Alkaliskalis• 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. 2. Behaviour of Covalent Oxides of PBehaviour of Covalent Oxides of Period 3 Elements in Water and Dilute Aleriod 3 Elements in Water and Dilute Alkaliskalis• 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. 2. Behaviour of Covalent Oxides of PBehaviour of Covalent Oxides of Period 3 Elements in Water and Dilute Aleriod 3 Elements in Water and Dilute Alkaliskalis• Chlorine(I) oxide
dissolves in water to form chloric(I) acid (also known as hypochlor
us 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. 2. Behaviour of Covalent Oxides of PBehaviour of Covalent Oxides of Period 3 Elements in Water and Dilute Aleriod 3 Elements in Water and Dilute Alkaliskalis• 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. 2. Behaviour of Covalent Oxides of PBehaviour of Covalent Oxides of Period 3 Elements in Water and Dilute Aleriod 3 Elements in Water and Dilute Alkaliskalis• Ionic equations:
P4O6(s) + 12OH–(aq) 4PO4
3–(aq) + 6H2O(l)
P4O10(s) + 12OH–(aq) 4PO4
3–(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. 2. Behaviour of Covalent Oxides of PBehaviour of Covalent Oxides of Period 3 Elements in Water and Dilute Aleriod 3 Elements in Water and Dilute Alkaliskalis• Ionic equations:
SO2(g) + 2OH–(aq) SO3
2–(aq) + H2O(l)
SO3(g) + 2OH–(aq) SO4
2–(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. 2. Behaviour of Covalent Oxides of PBehaviour of Covalent Oxides of Period 3 Elements in Water and Dilute Aleriod 3 Elements in Water and Dilute Alkaliskalis• Ionic equations:
Cl2O(g) + 2OH–(aq) 2OCl–(aq) + H2O(l)
Cl2O7(l) + 2OH–(aq) 2ClO4
–(aq) + H2O(l)
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 2elements 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 i
n water
Reacts vi
gorously
with water
to form Li
OH
Does not
react with
water
Reacts
with water
to form
H3BO3,
which is a
very weak
acid
CO:
Insoluble
in water
CO2:
Moderatel
y 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
Hydrolyze
s slowly to
form O2
and an
acidic
solution of
HF
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.26)
Oxide of Period 2 element
Li2O BeO B2O3
CO
CO2
N2O
NO
NO2
N2O4
N2O5
O2 OF2
Behaviour of oxides in dilute aci
ds
Reacts to form Li+
Reacts to form Be2+
Does not react with dilute acids
Do not react with dilute acids
Do not react with dilute acids
Does not react with dilute acids
Does not react with dilute acids
Periodicity in the behaviour of oxides of Periods 2elements 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.26)
Periodicity in the behaviour of oxides of Periods 2elements 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 i
n 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–
Does not
react with
dilute
alkalis
Reacts to
form F–
and O2
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 2elements 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 Acidic Acidic Neutral Acidic
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 3elements 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
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
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 3elements 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
Do not
react with
dilute
acids
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.27)
Periodicity in the behaviour of oxides of Periods 3elements in water, dilute acids and dilute alkalis
Oxide of
Period 3
element
Na2O
Na2O2
MgO Al2O3 SiO2
P4O6
P4O10
SO2
SO3
Cl2O
Cl2O7
Behaviour o
f oxides in
dilute alkali
s
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: Reac
ts to form
OCl– Cl2O7:
Reacts to
form ClO4–
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.27)
Check Point 39-2Check Point 39-2
Periodicity in the behaviour of oxides of Periods 3elements 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
AlkalineWeakly
acidicAmphoteric
Weakly
acidicAcidic Neutral Acidic
The END
(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)
(b) Carbon can form two oxides. Name the two oxides and draw their electronic structures.
Answer
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39.1 Bonding of the Oxides of Periods 2 and 3 Elements (SB p.22)
(b) Carbon monoxide (CO):
Carbon dioxide (CO2):
(a) Why does silicon(IV) oxide not react with water?
Answer(a) Silicon(IV) oxide does not react with water bec
ause the electronegativity values of silicon and
oxygen are very similar. The Si — O bond can
be considered as nonpolar, so there is no positi
ve centre for the lone pair electrons of the wate
r molecule to attack.
39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.27)
(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)
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39.2 Behaviour of Oxides of Periods 2 and 3 Elements in Water, Dilute Acids and Dilute Alkalis (SB p.27)
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