CBSE Class 11 Chemistry The P Block Elements Notes Set C

Download CBSE Class 11 Chemistry The P Block Elements Notes Set C in PDF format. All Revision notes for Class 11 Chemistry have been designed as per the latest syllabus and updated chapters given in your textbook for Chemistry in Standard 11. Our teachers have designed these concept notes for the benefit of Grade 11 students. You should use these chapter wise notes for revision on daily basis. These study notes can also be used for learning each chapter and its important and difficult topics or revision just before your exams to help you get better scores in upcoming examinations, You can also use Printable notes for Class 11 Chemistry for faster revision of difficult topics and get higher rank. After reading these notes also refer to MCQ questions for Class 11 Chemistry given our website

Revision Notes for Class 11 Chemistry P Block Elements

Class 11 Chemistry students should refer to the following concepts and notes for P Block Elements in standard 11. These exam notes for Grade 11 Chemistry will be very useful for upcoming class tests and examinations and help you to score good marks

P Block Elements Notes Class 11 Chemistry



p-block elements: last electron enters outermost p-orbital

6 groups (Gp 13-18)

General electronic configuration: ns2np6

Inert pair effect: Reluctance of the s-electrons of the valence shell to take part in bonding. Due to poor or ineffective shielding of the ns2 electrons, by the intervening d- and/or f-electrons

Inert pair effect increases down a group

Oxidation states: Elements down the group show lower oxidation states (2 units less) than highest group oxidation state

1st element of the group differs from rest, due to

small size

large (charge/radius) ratio

high ionization enthalpy

high electronegativity

unavailability of d-orbitals in valence shell

ability to form pπ-pπ bond to itself or to other second row elements

Group-13 Elements (Boron family)

√ Electronic configuration: ns2np1

√ Atomic radius increases down the group, but atomic radius of Ga is less than Al. This is due to poor shielding effect of the d-orbitals

 Inert pair effect is more pronounced in Tl

√ Oxidation state: B and Al show state of +3 only

• In and Tl show states of both +1 and +3

•The stability of +3 oxidation state decreases while that of +1 oxidation state increases as we move down the group

• For Tl, +1 oxidation state is more stable than +3 (redox potential data)

Tl3+ (aq) + 2e- → Tl+ (aq) E° = +1.25 V

• Stability of +1 oxidation state follows the trend: Al< Ga < In < Tl

√ Melting point of Boron is very high due to strong crystalline lattice

√ Halides: All the elements of group 13 (except Tl which forms thallous monohalides) form trihalides of the general formula MX3 where X = F, Cl, Br and I.

•All boron trihalides, i.e. BF3, BCl3, BBr3 and BI3 and aluminium trihalides i.e. AlCl3, AlBr3 and AlI3 (AlF3 being ionic) are covalent compounds.

• Boron trihalides exist as only monomers, aluminium trihalides exist as dimmers

class_9_chemistry_concept_p-block element

√ Nature of MX3: have only six electrons in the valence shell, electron-deficient

• have strong tendency to accept a pair of electrons to acquire the nearest inert gas configuration

• behave as Lewis acids

• on hydrolysis, trichlorides form tetrahedral species [M(OH)4]-

√ Reaction with oxygen: Forms oxides with formula E2O3.

• B2O3 is acidic and reacts with basic oxides to form metal borates

• Al2O3 forms a thin layer over aluminium surface and prevents further oxidation

Reaction with acids and alkalies: Aluminium shows amphoteric behaviour with acids and alkalies.

• Al dissolves in dilute HCl: 2Al + 6HCl → 2 Al3+ + 6 Cl- + 3H2

• Al reacts with alkali: 2Al + 2NaOH + 6H2O → 2Na[Al(OH)4]- + 3H2

• With conc. HNO3, forms a passive and protective oxide layer

√ Borax: (Na2B4O7. 10 H2O), It contains the tetranuclear units [B4O5 (OH)4]2- so, the correct formula is Na2[B4O5 (OH)4].8 H2O

• dissolves in water to form an alkaline solution

Na2B4O7 + 7 H2O → 2NaOH + 4 H3BO3

•On heating it loses water and swells up, turns into transparent liquid which solidifies into glass like bead. Used in borax-bead test

Na2B4O7. 10 H2O (heat) → Na2B4O7 (heat) →2NaBO2 + B2O3

√ Orthoboric acid (H3BO3): prepared by acidifying aqueous solution of borax 

Na2B4O7 + 2HCl + 5 H2O → 2NaCl + 4 B(OH)3

• Layered structure with planar BO3 atoms joined by H-bonds

• Weak, monobasic, aprotonic lewis acid B(OH)3 + 2HOH → [B(OH)4]- + H3O+

• On heating, B(OH)3 forms metaboric acid (HBO2) on further heating forms boric oxide (B2O3)

√ Diborane (B2H6): prepared by treating BF3 with LiAlH4

• Catches fire spontaneously in air, forms B2O3

• Readily hydrolysed to give boric acid

• Undergoes cleavage reactions with Lewis bases to give adducts B2H6 + 2 NMe3 → 2 BH3.NMe3

• Further heating of B2H6.2 NH3, gives Borazine (inorganic benzene) B3N3H6


3 B2H6 + 6 NH3 → 3[BH2(NH3)2]+[BH4]- heat 2 B3N3H6 + 12 H2

• Structure: 4 terminal H-atoms and 2 B-atoms lie in one plane (regular 2 centre-two e- bond) with 2 bridging H-atoms above and below this plane (3 centre-two e- banana bond)

class_9_chemistry_concept_p-block element_2

√ Uses of B and Al: Boron fibres are used in bullet-proof vest and light composite material for aircraft. absorb neutrons in nuclear reactors, heat resistant glasses, glasswool, antiseptic (orthoboric acid)

Al forms alloys, in packing , utensils and construction

Group-14 Elements (Carbon family)

√ Electronic configuration: ns2np2

√ Atomic radius increases down the group, large increase from C to Si, small increase

afterwards, due to presence of completely filled d- and f-orbitals

√ Physical properties: C is non-metal, Si and Ge are metalloid and Sn and Pb are metals 

√ Inert pair effect is more pronounced in Sn and Pb

√ Oxidation state: Generally state of +2 and +4

  • +4 state is shown by all elements. The stability of +4 oxidation state decreases while that of +2 oxidation state increases as we move down the group due to inert pair effect
  • The stability of +2 state increases in the sequence Si<Ge< Sn < Pb.
  • Compounds with +4 oxidation state are covalent in nature and are electron-precise molecules

√Covalency: Compounds having elements in oxidation state of +4 are covalent while with oxidation of +2 are ionic

  • On going down the group, the tendency to form covalent compounds decreases
  • Covalency of carbon is four as only s and p orbitals are present. Covalency is expanded in other elements as d-orbitals are present

√Catenation: Property of self-linking of atoms of an element through covalent bonds to form straight or branched chains and rings of different sizes is called catenation.

  • Depends on the strength of the element-element bond
  • The C-C bond strength is highest so, carbon show maximum tendency of catenation.
  • On moving down the group, the size increases and electronegativity decreases. So, the tendency for catenation have the order C > > > Si > Ge ≈ Sn > > Pb
  • Pb do not show any tendency for catenation

√pπ-pπ and pπ-dπ multiple bonding: Carbon has a unique ability to form pπ-pπ multiple bonds with itself (e.g. C=C, C≡C) and with other elements especially nitrogen and oxygen (C=O, C≡N).

  • Other elements have negligible tendency to form multiple bonds as size of atomic orbitals increases

√Reaction with oxygen: Two types of oxides : (i) monoxides and (ii) dioxide

  • Monoxide (MO): i.e. CO, SiO, GeO, SnO and PbO. SiO is stable at high temperature only
  • CO is neutral, GeO is acidic and SnO and PbO are amphoteric
  • Dioxides (MO2): i.e. CO2, SiO2, GeO2, SnO2 and PbO2.
  • CO2, SiO2 and GeO2 are acidic and SnO2 and PbO2 are amphoteric

√Reaction with water: Sn decomposes water to form SnO2 and H2

  • Pb not affected by water, as protective oxide film is present

√Reaction with halogen: Two types of halides: (i) dihalide and (ii) tetrahalide

  • Dihalide (MX2): Stability of these dihalides increases as we move down the group from C to Pb. So, SnCl2 and PbCl2 are quite stable
  • Generally ionic in nature and behave as reducing agent
  • Tetrahalides (MX4): Covalent compounds except SnF4 and PbF4, tetrahedral structure.
  • Stability of these decreases as we move from C to Pb, i.e. CCl4 > SiCl4 > GeCl4 > SnCl4 > PbCl4
  • Except CCl4, other tetrachlorides are hydrolysed by water as the central atom can accommodate lone pair of electrons from oxygen in d-orbital

√Allotropes of carbon: Two types: crystalline (diamond, graphite and fullerenes) and amorphous (coal, charcoal and coke)

  • Diamond: Each C is sp3 hybridised, linked to 4 other C atoms, forms 3- D, rigid, tetrahedron structure. Hardest substance due to extensive covalent bonding
  • Graphite: Each C is sp2 hybridised, forms planar hexagonal rings which forms layered structure held by Van der Waal’s forces. This leads to soft and slippery nature. One electron on each C-atom is delocalised in π-bond. This conducts electricity.
  • Fullerenes: Only pure form of carbon, cage-like molecules formed by heating of graphite in electric arc in presence of inert gases. E.g. Buckminsterfullerene with 20 six-membered rings and 12 five- membered rings. Aromatic with sp2 hybridised carbon atoms

√Carbon-monoxide (CO): Powerful reducing agent, so used in extraction of metals

  • On commercial scale, prepared by passage of steam over hot coke. Mixture of CO and H2 is water gas or synthesis gas.
  • Mixture of CO and N2 is producer gas
  • :C≡O: have one σ and two π bonds. Due to lone pair of e-, acts as donor in metal carbonyls.
  • Highly poisonous as forms stable complex with haemoglobin

√Carbon-dioxide (CO2): Monomeric, linear molecule with sp hybridisation, pπ-pπ bonding and exists as a gas

  • Forms H2CO3 (weak dibasic acid) with water
  • Helps in photosynthesis, causes green-house effect and global warming
  • Dry ice (solid CO2) as refrigerant

√Silicon dioxide (SiO2): Covalent, 3-D network having each Si atom covalently bonded to oxygen in a tetrahedral manner 

  • Generally non-reactive due to high bond enthalpy of Si-O bond
  • Used as piezoelectric material in form of quartz

√ Silicones: Synthetic organosilicon compounds with repeating R2SiO units held by Si- O-Si linkage

  • Prepared by hydrolysis of alkyl or aryl substituted silicon chlorides (RnSiCl(4-n))

 CBSE Class 9 Chemistry-P-Block Elements

  • Water repellent, heat resistant, chemically inert, resistant to oxidation and attack by organic acids, good electrical insulators and biocompatible
  • Used for making sealant, greases, water-proofing, insulators and surgical and cosmetic implants 

√Silicates: SiO44- having Si atom bonded to 4 Oxygen atoms in tetrahedron fashion

  • -ve charge is neutralised by +vely charged metal ions
  • E.g. glass, cement etc.

√Zeolites: Aluminosilicates having a negative charge

  • Used as catalyst in cracking of hydrocarbons and isomerisation
  • E.g. ZSM-5

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