The p-Block Elements Class 11 Notes Chemistry

 Page 1


General outer Electronic configuration : ns
2
np
1–6
.
Inert Pair Effect:
? Reluctance of ns
2
 electrons of valence shell to participate in bond formation
is termed as inert pair effect.
? It arises due to poor or insufficient shielding of ns
2
 electrons by intervening
d- or f-electrons & hence increases down the group.
Causes of Anomalous Behaviour of First Element in groups of p-Block:
(i) Very small size
(ii) Unavailability of vacant d-orbital
(iii) Tendency to form p
p
 –  p
p
 multiple bonds.
Group No-13 Elements: (B, Al, Ga, In, Tl, Nh)
? General Electronic Configuration: ns
2
 np
1
? Atomic radius: B < Ga < Al < In <TI
r
Ga
 < r
Al
 due to ineffective shielding of valence electrons by intervening 3d-
electrons in Ga.
? Ionization Enthalpies:        : B > Tl > Ga > Al > In
? Electronegativity: B > Tl > In > Ga > Al
? Oxidation States: B (+3), Al (+3), Ga (+3, +1), In (+3, +1), Tl (+1, +3)
Tl (+1) is more stable than Tl (+3) due to inert pair effect.
Page 2


General outer Electronic configuration : ns
2
np
1–6
.
Inert Pair Effect:
? Reluctance of ns
2
 electrons of valence shell to participate in bond formation
is termed as inert pair effect.
? It arises due to poor or insufficient shielding of ns
2
 electrons by intervening
d- or f-electrons & hence increases down the group.
Causes of Anomalous Behaviour of First Element in groups of p-Block:
(i) Very small size
(ii) Unavailability of vacant d-orbital
(iii) Tendency to form p
p
 –  p
p
 multiple bonds.
Group No-13 Elements: (B, Al, Ga, In, Tl, Nh)
? General Electronic Configuration: ns
2
 np
1
? Atomic radius: B < Ga < Al < In <TI
r
Ga
 < r
Al
 due to ineffective shielding of valence electrons by intervening 3d-
electrons in Ga.
? Ionization Enthalpies:        : B > Tl > Ga > Al > In
? Electronegativity: B > Tl > In > Ga > Al
? Oxidation States: B (+3), Al (+3), Ga (+3, +1), In (+3, +1), Tl (+1, +3)
Tl (+1) is more stable than Tl (+3) due to inert pair effect.
? Nature of Compounds: Compounds of group 13 elements are electron
deficient i.e. Lewis Acid and hence used as industrial catalyst e.g. BF
3
, AlCl
3
.
? Oxides:  B
2
O
3
 Al
2
O
3
, Ga
2
O
3
 ln
2
O
3
 Tl
2
O
Acidic Amphoteric Basic Strongly Basic
? Halides: MX
3
 type, Electron deficient (Lewis acid), AICI
3
 exist as dimer
? Borax: Na
2
B
4
O
7
.10H
2
O. On heating it form transparent glassy bead
consisting of NaBO
2
 + B
2
O
3
.
? Boric acid: H
3
BO
3
, It acts as a Lewis acid by accepting electron pair from
OH
–
 ions of water.
? Diborane: B
2
H
6
, Colourless & toxic gas, acts as Lewis acid due to having
electron deficient 3c-2e
–
 bonds. Obtained by treating BF
3
 with LiAIH
4
 or
NaH, Also obtained by treating NaBH
4
 with l
2
.
? Borazine: B
3
N
3
H
6
, It is isostructural with benzene and hence known as inor-
ganic benzene. Prepared by heating B
2
H
6
 withNH
3
Group -14 Elements: (C, Si, Ge, Sn, Pb,Fl)
? General Electronic Configuration: ns
2
 np
2
? Atomic radius: C < Si < Ge < Sn < Pb
? lonisation Enthalpy: LiH
x
 : C > Si > Ge > Sn < Pb
? Oxidation States: C (+4), Si (+4), Ge (+4, +2), Sn (+4, +2), Pb (+4, +2)
Pb (+2) is more stable than Pb (+4) due to inert pair effect.
? Oxides: Form di oxides (MO
2
) & mono oxides (MO).
PbO
2
 is powerfull oxidizing agent because Pb stabilizes in +2 oxidation state
due to inert pair effect. CO
2
 is gas while SiO
2
 is network solid because C has
ability to form p
p
 — p
p
 multiple bonds.
? Halides: Form tetra halides (MX
4
) & dihalides (MX
2
).
Tetra halides are more covalent due to greater polarizing power of cation.
CCI
4
 is not hydrolysed with water as C has no vacant d-orbital to accept
electron pair from water.
Page 3


General outer Electronic configuration : ns
2
np
1–6
.
Inert Pair Effect:
? Reluctance of ns
2
 electrons of valence shell to participate in bond formation
is termed as inert pair effect.
? It arises due to poor or insufficient shielding of ns
2
 electrons by intervening
d- or f-electrons & hence increases down the group.
Causes of Anomalous Behaviour of First Element in groups of p-Block:
(i) Very small size
(ii) Unavailability of vacant d-orbital
(iii) Tendency to form p
p
 –  p
p
 multiple bonds.
Group No-13 Elements: (B, Al, Ga, In, Tl, Nh)
? General Electronic Configuration: ns
2
 np
1
? Atomic radius: B < Ga < Al < In <TI
r
Ga
 < r
Al
 due to ineffective shielding of valence electrons by intervening 3d-
electrons in Ga.
? Ionization Enthalpies:        : B > Tl > Ga > Al > In
? Electronegativity: B > Tl > In > Ga > Al
? Oxidation States: B (+3), Al (+3), Ga (+3, +1), In (+3, +1), Tl (+1, +3)
Tl (+1) is more stable than Tl (+3) due to inert pair effect.
? Nature of Compounds: Compounds of group 13 elements are electron
deficient i.e. Lewis Acid and hence used as industrial catalyst e.g. BF
3
, AlCl
3
.
? Oxides:  B
2
O
3
 Al
2
O
3
, Ga
2
O
3
 ln
2
O
3
 Tl
2
O
Acidic Amphoteric Basic Strongly Basic
? Halides: MX
3
 type, Electron deficient (Lewis acid), AICI
3
 exist as dimer
? Borax: Na
2
B
4
O
7
.10H
2
O. On heating it form transparent glassy bead
consisting of NaBO
2
 + B
2
O
3
.
? Boric acid: H
3
BO
3
, It acts as a Lewis acid by accepting electron pair from
OH
–
 ions of water.
? Diborane: B
2
H
6
, Colourless & toxic gas, acts as Lewis acid due to having
electron deficient 3c-2e
–
 bonds. Obtained by treating BF
3
 with LiAIH
4
 or
NaH, Also obtained by treating NaBH
4
 with l
2
.
? Borazine: B
3
N
3
H
6
, It is isostructural with benzene and hence known as inor-
ganic benzene. Prepared by heating B
2
H
6
 withNH
3
Group -14 Elements: (C, Si, Ge, Sn, Pb,Fl)
? General Electronic Configuration: ns
2
 np
2
? Atomic radius: C < Si < Ge < Sn < Pb
? lonisation Enthalpy: LiH
x
 : C > Si > Ge > Sn < Pb
? Oxidation States: C (+4), Si (+4), Ge (+4, +2), Sn (+4, +2), Pb (+4, +2)
Pb (+2) is more stable than Pb (+4) due to inert pair effect.
? Oxides: Form di oxides (MO
2
) & mono oxides (MO).
PbO
2
 is powerfull oxidizing agent because Pb stabilizes in +2 oxidation state
due to inert pair effect. CO
2
 is gas while SiO
2
 is network solid because C has
ability to form p
p
 — p
p
 multiple bonds.
? Halides: Form tetra halides (MX
4
) & dihalides (MX
2
).
Tetra halides are more covalent due to greater polarizing power of cation.
CCI
4
 is not hydrolysed with water as C has no vacant d-orbital to accept
electron pair from water.
? Catenation: C >> Si > Ge ˜ Sn >> Pb
? Allotrops of carbon: Diamond (sp
3
), Graphite (sp
2
), Fullerenes (sp
2
)
? Silicones: Silicones are synthetic organosilicon compounds containing
R
2
SiO repeating units. Silicones are water repellent, heat resistant, chemi-
cally inert, electrical insulators, resistant to oxidation.
? Silicates: Silicates are compounds in which anions are derived from
Si–o–si– tetrahedral units.
? Zeolites: Zeolites are 3D silicates in which some of the Si atoms are replaced
by Al
3+
 ions and negative charge is balanced by cations such as Na
+
, K
+
,
Ca
2+
 etc.
? ZSM-5 is used in petrochemical industries to convert methanol into petrol.
Group - 15 Elements: (N, P, As, Sb, Bi, Mc)
? General Electronic Configuration: ns
2
 np
3
? Atomic radius: N < P < As < Sb < Bi
? lonisation Enthalpy: D
i
H
1
: N > P > As > Sb > Bi
? Oxidation States: N (+5, +3), P (+5,+3), As (+5, +3), Sb (+5,+3), Bi (+5,
+3) Bi (+3) is more stable than Bi (+5) due to inert pair effect.
? Oxides: Form trioxides (M
2
O
3
) & pentaoxides (M
2
O
5
).
? Halides: Form trihalides (MX
3
) & pentahalides (MX
5
).
Nitrogen does not form penta halides because it cannot extend its covalency
beyond four due to absence of vacant d-orbitals.
Pentahalides are more covalent than trihalides due to greater polarizing
power of cation.
? Hydrides: MH
3
 type, Lewis base, pyramidal structure
  NH
3
 > PH
3
 > AsH
3
 > SbH
3
 > BiH
3
 
(Basic character, Bond angle & Thermal Stability) 
  NH
3 
< PH
3 
< AsH
3 
< SbH
3 
< BiH
3
 
(Reducing Character) PH
3
< AsH
3
< NH
3
< SbH
3
< BiH
3
 (Boiling point)
Page 4


General outer Electronic configuration : ns
2
np
1–6
.
Inert Pair Effect:
? Reluctance of ns
2
 electrons of valence shell to participate in bond formation
is termed as inert pair effect.
? It arises due to poor or insufficient shielding of ns
2
 electrons by intervening
d- or f-electrons & hence increases down the group.
Causes of Anomalous Behaviour of First Element in groups of p-Block:
(i) Very small size
(ii) Unavailability of vacant d-orbital
(iii) Tendency to form p
p
 –  p
p
 multiple bonds.
Group No-13 Elements: (B, Al, Ga, In, Tl, Nh)
? General Electronic Configuration: ns
2
 np
1
? Atomic radius: B < Ga < Al < In <TI
r
Ga
 < r
Al
 due to ineffective shielding of valence electrons by intervening 3d-
electrons in Ga.
? Ionization Enthalpies:        : B > Tl > Ga > Al > In
? Electronegativity: B > Tl > In > Ga > Al
? Oxidation States: B (+3), Al (+3), Ga (+3, +1), In (+3, +1), Tl (+1, +3)
Tl (+1) is more stable than Tl (+3) due to inert pair effect.
? Nature of Compounds: Compounds of group 13 elements are electron
deficient i.e. Lewis Acid and hence used as industrial catalyst e.g. BF
3
, AlCl
3
.
? Oxides:  B
2
O
3
 Al
2
O
3
, Ga
2
O
3
 ln
2
O
3
 Tl
2
O
Acidic Amphoteric Basic Strongly Basic
? Halides: MX
3
 type, Electron deficient (Lewis acid), AICI
3
 exist as dimer
? Borax: Na
2
B
4
O
7
.10H
2
O. On heating it form transparent glassy bead
consisting of NaBO
2
 + B
2
O
3
.
? Boric acid: H
3
BO
3
, It acts as a Lewis acid by accepting electron pair from
OH
–
 ions of water.
? Diborane: B
2
H
6
, Colourless & toxic gas, acts as Lewis acid due to having
electron deficient 3c-2e
–
 bonds. Obtained by treating BF
3
 with LiAIH
4
 or
NaH, Also obtained by treating NaBH
4
 with l
2
.
? Borazine: B
3
N
3
H
6
, It is isostructural with benzene and hence known as inor-
ganic benzene. Prepared by heating B
2
H
6
 withNH
3
Group -14 Elements: (C, Si, Ge, Sn, Pb,Fl)
? General Electronic Configuration: ns
2
 np
2
? Atomic radius: C < Si < Ge < Sn < Pb
? lonisation Enthalpy: LiH
x
 : C > Si > Ge > Sn < Pb
? Oxidation States: C (+4), Si (+4), Ge (+4, +2), Sn (+4, +2), Pb (+4, +2)
Pb (+2) is more stable than Pb (+4) due to inert pair effect.
? Oxides: Form di oxides (MO
2
) & mono oxides (MO).
PbO
2
 is powerfull oxidizing agent because Pb stabilizes in +2 oxidation state
due to inert pair effect. CO
2
 is gas while SiO
2
 is network solid because C has
ability to form p
p
 — p
p
 multiple bonds.
? Halides: Form tetra halides (MX
4
) & dihalides (MX
2
).
Tetra halides are more covalent due to greater polarizing power of cation.
CCI
4
 is not hydrolysed with water as C has no vacant d-orbital to accept
electron pair from water.
? Catenation: C >> Si > Ge ˜ Sn >> Pb
? Allotrops of carbon: Diamond (sp
3
), Graphite (sp
2
), Fullerenes (sp
2
)
? Silicones: Silicones are synthetic organosilicon compounds containing
R
2
SiO repeating units. Silicones are water repellent, heat resistant, chemi-
cally inert, electrical insulators, resistant to oxidation.
? Silicates: Silicates are compounds in which anions are derived from
Si–o–si– tetrahedral units.
? Zeolites: Zeolites are 3D silicates in which some of the Si atoms are replaced
by Al
3+
 ions and negative charge is balanced by cations such as Na
+
, K
+
,
Ca
2+
 etc.
? ZSM-5 is used in petrochemical industries to convert methanol into petrol.
Group - 15 Elements: (N, P, As, Sb, Bi, Mc)
? General Electronic Configuration: ns
2
 np
3
? Atomic radius: N < P < As < Sb < Bi
? lonisation Enthalpy: D
i
H
1
: N > P > As > Sb > Bi
? Oxidation States: N (+5, +3), P (+5,+3), As (+5, +3), Sb (+5,+3), Bi (+5,
+3) Bi (+3) is more stable than Bi (+5) due to inert pair effect.
? Oxides: Form trioxides (M
2
O
3
) & pentaoxides (M
2
O
5
).
? Halides: Form trihalides (MX
3
) & pentahalides (MX
5
).
Nitrogen does not form penta halides because it cannot extend its covalency
beyond four due to absence of vacant d-orbitals.
Pentahalides are more covalent than trihalides due to greater polarizing
power of cation.
? Hydrides: MH
3
 type, Lewis base, pyramidal structure
  NH
3
 > PH
3
 > AsH
3
 > SbH
3
 > BiH
3
 
(Basic character, Bond angle & Thermal Stability) 
  NH
3 
< PH
3 
< AsH
3 
< SbH
3 
< BiH
3
 
(Reducing Character) PH
3
< AsH
3
< NH
3
< SbH
3
< BiH
3
 (Boiling point)
? Oxides of Nitrogen: Nitrogen having ability to form p
p
 – p
p
 multiple bonds
can form oxides in all oxidation states from +1 to +5 i.e. N
2
O, NO,N
2
O
3
,
NO
2
,N
2
O
4
 & N
2
O
5
? Dinitrogen (N
2
): Much less reactive due to high bond enthalpy of N =N.
Prepared by heating (NH
4
)
2
Cr
2
O
7
 or a solution of NH
4
Cl + NaNO
2
.
? Ammonia (NH
3
): Pungent & irritating smell gas. It is prepared on commer-
cial scale by Haber's process. NH
3
 acts as Lewis base /Ligand / complexing
agent due to the presence of electron pair on N atom.
? Nitric acid (HNO
3
): It is very powerfull oxidizing agent because it readi-
ly gives nascent oxygen both in concentrated or dilute form. Concentrated
HNO
3
 oxidizes non-metals to their oxoacids and metals to their nitrates.
? Allotropes of Phosphorous: White (Most reactive due to angular strain),
Red & Black phosphorous.
? Phosphine (PH
3
): Poisonous gas with rotten fish smell, it is prepared by
heating white phosphorous with concentrated. NaOH in inert atmosphere of
CO
2
. Phosphine can also be prepared by dropping H
2
O or HCI on Ca
3
P
2
.
? Phosphorous trichloride (PCl
3
): Colourless liquid, fumes in moisture due
to the formation of HCI.
? Phosphorous pentachloride (PCl
5
): In gaseous state it is covalent (trigonal
bipyramid) but in solid state it is ionic i.e. [PCl
4
]
+
[PCl
6
]
–
.
? Oxoacids of Phosphorous:
  (i)  Hypophosphorous acid (H
3
PO
2
): Monobasic, reducing
(ii) Phosphorous acid (H
3
PO
3
): Dibasic/reducing
(iii) Phosphoric acid (H
3
PO
4
): Tribasic, Non-reducing
(iv) Hypophosphoric acid (H
4
P
2
O
6
): Tetrabasic, non-reducing a          
(v) Pyrophosphoric acid (H
4
P
2
O
7
): Tetrabasic, non-reducing