11C11

​

The p-Block Elements

Group 13-18

ns²np^1-6

General Electronic Configuration:

(Except He)

The p-Block Elements

Group 13

Group 14

11C11.1

​

Boron Family

11C11.1 Boron Family

Learning Objectives

Introduction to Boron Family

Trends in General Properties of Group 13 Elements

Properties of Group 13 Elements

Anomalous Behaviour of Boron

11C11.1

​

CV 1

​

Introduction to Boron Family

Introduction to Boron Family

• B, Al, Ga, In, Tl and Nh
• ns²np¹
• Boron is a fairly rare element.

• Borax occurs in Puga Valley (Ladakh) and Sambhar Lake (Rajasthan).
• Al is the most abundant metal and the 3^rd most abundant element in the earth’s crust.

Orthoboric Acid

Borax

Kernite

Electronic Configurations of Group-13 Elements

Radioactive

Poor screening of d-subshell

Inert Pair Effect

ConcepTest

​

Ready for Challenge

Pause the video

Time duration : 2 minutes

The elements B, Al, Ga, In and Tl are placed in the same group of the periodic table. Give reason.

Q.

The elements B, Al, Ga, In and Tl are placed in the same group of the periodic table. Give reason.

Q.

Sol.

11C11.1

​

CV 2

​

Trends in General Properties of Group 13 Elements

Trends in Atomic Size

Trends in Ionisation Enthalpy

• Trend:

In < Al < Ga < Tl < B

• Trend:

Al < Ga < In < Tl < B

Trends in Electronegativity

11C11.1

​

CV 3

​

Properties of Group 13 Elements-I

• Boron is non-metallic, extremely hard and black coloured solid.
• Due to very strong crystalline lattice, boron has unusually high melting point.
• Rest of the members are soft metals with low melting point and high electrical conductivity.
• Gallium has low melting point (303K) but high boiling point (2676 K).
• Density of the elements increases down the group.

Physical Properties

Oxidation State and Chemical Reactivity

• Small size and high I.E. mainly forms covalent bond.

• Most electropositive and shows O.S. + 3.

• Electropositive and shows O.S. + 3.

• Shows O.S. +3 and +1.

• Mainly shows O.S. +1 due to poor screening by 4f and 5d subshell electrons (Inert Pair Effect).

Relative stability of +1 O.S. progressively increases down the group:

Al < Ga < In < Tl

• +3 oxidation state is highly oxidising in character.
• The compounds in +1 oxidation state are more ionic than those in +3 oxidation state.

Oxidation State and Chemical Reactivity

• B and Al form trivalent covalent compounds which are Electron Deficient.

`

Planar

Borane-Ammonia Adduct

Tetrahedral

Oxidation State and Chemical Reactivity

• AlCl₃ achieves stability by forming a dimer.

Oxidation State and Chemical Reactivity

• AlCl₃ achieves stability by forming a dimer.

ConcepTest

​

Ready for Challenge

Q.

Pause the video

Time duration : 2 minutes

Q.

Sol.

Complete Octet

6 electrons in valence shell of Al

11C11.1

​

CV 4

​

Properties of Group 13 Elements-II

Reaction with Air

Acidic

Amphoteric

Basic

Reaction with Acids and Alkalies

Sodiumtetrahydroxyaluminate(III)

Reaction with Halogens

Due to similar size the extent of overlapping is high

Less electron deficiency

Due to difference in size the extent of overlapping is poor

High electron deficiency

ConcepTest

​

Ready for Challenge

Pause the video

Time duration : 2 minutes

Why Al does not react with concentrated nitric acid?

Q.

Q.

Sol.

Al

Why Al does not react with concentrated nitric acid?

11C11.1

​

CV 5

​

Anomalous Behaviour of Boron

Anomalous Behaviour of Boron

• Small Size
• High Electronegativity
• Absence of d-orbital

Some dissimilarities with rest members of the group

Diagonal Relationship with Si

Dissimilarities with Al

Diagonal Relationship with Si

Summary

Acidic

Amphoteric

Basic

Summary

Group 13 (E)

Air

Steam

Acid

Halogens

11C11.1 Boron Family

Reference Questions:

NCERT Exercise Questions : 11.1, 11.2, 11.3, 11.4, 11.7, 11.8, 11.14, 11.15

Workbook Questions : 1, 2, 3, 4, 12, 13, 19

11C11.2

​

Some Important Compounds of Boron

11C11.2 Some Important Compounds of Boron

Learning Objectives

Borax

Orthoboric Acid

Diborane

Uses of Group 13 Elements

11C11.2

​

CV 1

​

Borax

Borax

• Borax can also be prepared from Boric acid:

• Also known as Tincal or Suhaga (contains 45% Borax).

Properties of Borax

• Borax is know to exist in three forms:

Prismatic form

Octahedral form

(Jeweller’s Borax)

Borax Glass

Properties of Borax

• Basic in nature:

Strong Base

Weak Acid

• Aqueous solution of Borax acts as a Buffer.

• Action of Heat:

Sodium metaborate

Boric anhydride

Borax Bead (Glassy Mass)

• Borax bead test is used to identify Transition Metals in the laboratory.

Borax Bead Test

Oxidising Flame

Reducing Flame

• Mixture of Metal Salt and Borax Bead is heated in Bunsen burner.
• Metal metaborates are formed which are coloured in nature.

Cobalt metaborate

Blue

Bunsen Burner

Borax Bead Test

ConcepTest

​

Ready for Challenge

Pause the video

Time duration : 2 minutes

What are the hybridisation of boron atoms in borax ?

Q.

O

O

B

O

O

O

B

What are the hybridisation of boron atoms in borax ?

Q.

Sol.

11C11.2

​

CV 2

​

Orthoboric Acid

Orthoboric Acid

Borax

Orhtoboric Acid

Colemanite

Orhtoboric Acid

Properties of Orthoboric Acid

• Monobasic acid.

​

• Action of Heat:

Metaboric Acid

Tetraboric Acid

Boric Anhydride

11C11.2

​

PSV 1

Starting from boric acid how would you prepare?

1. Boric anhydride
2. Boron trichloride
3. Boron hydride

Q.

Sol.

1. Boric anhydride

2. Boron trichloride

3. Boron hydride

11C11.2

​

PSV 2

Q.

Sol.

X (Borax)

Strong Base

X (Borax)

Y (Glassy Bead)

X (Borax)

Z (Boric Acid- White Crystal)

11C11.2

​

CV 3

​

Diborane

Diborane

Diborane

Preparation of Diborane

3. Silent Electric Discharge:

Properties of Diborane

• Colourless.
• Highly Toxic.
• Disagreeable odour and causes headache.
• Boiling Point 180 K.
• Action of Heat:

• Combustion:

Properties of Diborane

• Lewis Acid:

Borane Adduct

Borane Adduct

Borane Adduct

Borazine

Borazine

(Inorganic Benzene)

Properties of Diborane

ConcepTest

​

Ready for Challenge

Pause the video

Time duration : 2 minutes

Q.

Q.

Tetrahedral

Sol.

Tetrahedral

11C11.2

​

CV 4

​

Uses of Group 13 Elements

Uses of Group 13 Elements

Refractory Material

Boron as:

Bulletproof Jacket

Aeroplane Components

• Boron-10 (₁₀B) isotope has high ability to absorb neutrons, hence metal borides are used in nuclear industry as protective shields and control rods.

Uses of Group 13 Elements

Borax and Orthoboric Acid as:

Glass Wool

Heat Resistant Glass

Fibre Glass

Aluminium as:

Uses of Group 13 Elements

Wire

Utensils

Pipes and Tubes

Foil

Summary

Reference Questions:

NCERT Exercise Questions : 11.5, 11.6, 11.19, 11.20, 11.31, 11.33, 11.34, 11.35

Workbook Questions : 16

11C11.2 Some Important Compounds of Boron

11C11.3

​

Carbon Family

11C11.3 Carbon Family

Learning Objectives

Introduction to Carbon Family

Trends in General Properties of Group 14 Elements

Properties of Group 14 Elements

Anomalous Behaviour of Carbon

11C11.3

​

CV 1

​

Introduction to Carbon Family

• C, Si, Ge, Sn, Pb and Fl
• Carbon is the 17^th most abundant element by mass in the earth’s crust.

Coal

Graphite

Diamond

Carbon Family

• Two stable isotopes: ₁₂C and ₁₃C.
• Radioactive isotope: ₁₄C with half-life 5770 years and used for carbon dating.

• Silicon is the 2^nd most abundant element by mass (27.7 %) in the earth’s crust.

Carbon Family

Silica Sand

Silicates

Electronic Configurations of Group-14 Elements

Radioactive

Inert Pair Effect

11C11.3

​

CV 2

​

Trends in General Properties of Group 14 Elements

Trends in Atomic Size

• Si to Pb a small increase in radius
• Poor screening of d & f-subshell

• Considerable increase in covalent radius from C to Si

• Trend:

C < Si < Ge < Sn < Pb

Trends in Ionisation Enthalpy

• Trend:

Sn < Pb < Ge < Si < C

• The EN values for elements from Si to Sn are almost the same.

Trends in Electronegativity

11C11.3

​

CV 3

​

Properties of Group 14 Elements-I

Physical Properties

C

Si

Ge

Sn

Pb

Non-Metal

Metalloid

Metal

• All members of group 14 are solids.

• M.P. and B.P. of group 14 elements are much higher than those of corresponding elements of group 13.

Oxidation State and Chemical Reactivity

• High I.E. mainly forms covalent bond in + 4 O.S.

• Higher members show O.S. +2 due to poor screening by 4f and 5d subshell electrons (Inert Pair Effect).

Less Stable

Less Stable

More Stable

More Stable

Reducing Agent

Oxidising Agent

Oxidation State and Chemical Reactivity

11C11.3

​

PSV 1

Q.

Due availability of vacant d-orbitals in Si, back bond is formed between Si and N

Sol.

11C11.3

​

CV 4

​

Properties of Group 14 Elements-II

Reaction with Oxygen

Monoxide

Dioxide

Neutral

Acidic

Amphoteric

Acidic

Amphoteric

Reaction with Halogens

Tetrahedral

Hydrolysis of Halides

• Except Carbon halides, other halides are easily hydrolysed.

Silicic Acid

Reaction with Water

ConcepTest

​

Ready for Challenge

Q.

Pause the video

Time duration : 2 minutes

Q.

Sol.

11C11.3

​

CV 5

​

Anomalous Behaviour of Carbon

Anomalous Behaviour of Boron

• Small Size
• High Electronegativity
• Absence of d-orbital

Some dissimilarities with rest members of the group

Catenation

• Tendency to link with one another through covalent bonds to form chains and rings.

Anomalous Behaviour of Carbon

ConcepTest

​

Ready for Challenge

Bond energy is highest for:

Pause the video

Time duration : 2 minutes

Q.

Bond energy is highest for:

Q.

Sol.

Summary

Neutral

Acidic

Amphoteric

Acidic

Amphoteric

Summary

Group 14 (E)

Except C

Except C & Si

Except C & Si

11C11.3 Carbon Family

Reference Questions:

NCERT Exercise Questions : 11.10, 11.13, 11.23, 11.24, 11.26, 11.29, 11.37

Workbook Questions : 5, 6, 7, 9, 14, 15, 20

11C11.4

​

Some Important Compounds of Carbon and Silicon

11C11.4 Some Important Compounds of Carbon and Silicon

Learning Objectives

Allotropes of Carbon

Oxides of Carbon

Silica and Silicones

Silicates and Zeolites

11C11.4

​

CV 1

​

Allotropes of Carbon

Allotropes of Carbon

Graphite

Diamond

Fullerenes

Graphite

142 pm

335 pm

Diamond

Fullerenes

• The remaining electron at each carbon is delocalised in molecular orbitals, which in turn give aromatic character to molecule.

Coal

• Crude form of carbon.

Peat

55-60%

Lignite

60-68%

Bituminous

70-88%

Anthracite

90-95%

• In India, the common variety of coal is Bituminous.

11C11.4

​

CV 2

​

Oxides of Carbon

Carbon Monoxide

Water Gas or Synthesis Gas

Properties of Carbon Monoxide

Carbon Dioxide

Properties of Carbon Dioxide

Milky white ppt.

Properties of Carbon Dioxide

11C11.4

​

PSV 1

What is producer gas?

Q.

Sol.

Producer Gas

• Used primarily as an industrial fuel for iron and steel manufacturing.

ConcepTest

​

Ready for Challenge

Q.

Pause the video

Time duration : 2 minutes

Q.

Sol.

Milky white ppt.

Water Soluble

Hence the correct option is d) formation of water soluble calcium bicarbonate.

11C11.4

​

CV 3

​

Silica and Silicones

Silica

Quartz

Cristobalite

Tridymite

• Occurs in several crystallographic forms:

Silica

Produces internal charge under high mechanical stress

Silicones

Dialkyldichlorosilane

Dialkylsilandiol

Silicone

n

• Water repelling in nature.
• High thermal stability.
• Resistant to oxidation and chemical reagents.
• Used as sealant, greases, electrical insulators and for water proofing of fabrics.
• Due to biocompatibility it is used in surgical and cosmetic implants.

Silicones

ConcepTest

​

Ready for Challenge

Pause the video

Time duration : 2 minutes

Q.

When Silica is treated with sodium carbonate, then which of the following gas is liberated ?

When Silica is treated with sodium carbonate, then which of the following gas is liberated ?

Q.

Sol.

ConcepTest

​

Ready for Challenge

Pause the video

Time duration : 2 minutes

Q.

Sol.

Q.

11C11.4

​

CV 4

​

Silicates and Zeolites

Silicates

Examples:

Orthosilicate

Silicates

Pyrosilicate:

Examples:

Silicates

Cyclic or Ring Silicates:

Examples:

Silicates

Chain Silicates:

Examples:

Silicates

Two Dimensional Sheet Silicates:

Examples:

Silicates

Three Dimensional Silicates:

Examples:

Quartz, Tridymite, Fledspars, Zeolites

Zeolites

Summary

Allotropes of Carbon

Graphite

Diamond

Fullerenes

• Silicones are organosilicon polymers.

Summary

Silicates

Orthosilicates

Pyrosilicates

Cyclic Silicates

Chain Silicates

2-D Sheet Silicates

• Zeolites are 3-D Aluminosilicates

Reference Questions:

NCERT Exercise Questions : 11.17, 11.18, 11.21, 11.25, 11.32, 11.36, 11.38

Workbook Questions : 8, 10, 17

11C11.4 Some Important Compounds of Carbon and Silicon