mastering organic chemistry and inorganic

Mastering Organic Chemistry (Class XII)

Focussing on NCERT questions: The NCERT Part II comprises of organic chemistry and contributes to 28 marks in the examination.

An analysis of previous years question papers depicts that many questions are asked as it is from the NCERT textbooks.

The table given below shows the question numbers of the questions in the NCERT book which

have been asked in the examination. Note that, many questions are being asked repeatedly.

Units Marks 2012 2011 2010 2009 2008 2007 2006

Haloalkanes

and Haloarenes 4

Example 10.2

(vi) Table 10.1 Example

10.7

Example

10.6, 10.17

Ex 10.2

(i)10.9 (i),

10.14 (vii)

- -

Alcohols,

Phenols and

Ethers

4

Exercise 11.5,

11.15 11.18 (ii),

11.31 (iv)

11.20 (ii,

iv), 11.18 (i,

iii)

11.3 (v)

11.3 (ii),

11.21 (ii,

ii, vi)

11.22 -

Aldehydes,

Ketones and

Carboxylic

Acids

6

Example 12.5

(i, iv),Exercise

12.10,Exercise

12.12,

Exercise 12.13

(i, vi)

12.13 (i,

iv), 12.16

(ii, iv),

12.17 (i,

ii)

Fig 12.2,

12.11, 12.13

(iii, vii),

12.12 (i, ii)

12.16 (ii),

12.19, 12.17

(iv)

12.12 (ii),

12.17 (i, x,

xi), 12.16

(ii, iii)

Table

12.1,

12.13 (i)

12.16 (ii),

12.13 (vii)

Amines 4

Exercise 13.7

(i and iii),

Exercise 13.11

(ii, v)

13.4 (ii)

Table 13.1,

13.4 (i,ii, iii-

a, iv)

Ex 13.4,

13.7 (iii, iv)

13.3 (I, iii,

v) 13.12 13.2 (v)

Biomolecules 4 Exercise 14.12 14.12,

14.13 14.17, 14.22

14.12 (i),

table 14.3

14.12 (i,

iii), 14.10 14.12 (ii)

14.15,

table14.3

Polymers 3 -

15.2 15.11 15.12 15.17 15.12,

15.16 15.12, 15.15

Chemistry in

Everyday Life 3

Exercise 16.10

16.15 16.21 (i)

16.15,

16.17, 16.21

(i)

16.12,

16.22 16.15 -

So, mark these questions in the NCERT book and go through all the NCERT solutions

thoroughly. For this you can also refer to the NCERT solutions section on meritnation.com

IUPAC Nomenclature questions: A conclusion from previous years papers is that, 90% of the questions related to nomenclature of organic compounds usually come from the

tables of common and IUPAC names or in-text examples present in NCERT book. Below

is a summarized chart of all the tables and in-text examples meant for nomenclature.

Haloalkanes and Haloarenes Table 10.1, example 10.1 and example 10.2

Alcohols, Phenols and Ethers Table 11.1, 11.2, example 11.1 and in-text question

11.3

Aldehydes, ketones and carboxylic acids Table 12.1 and intext questions 12.1, Table 12.3

and in-text question 12.6

Amines Table 13.1

Note: Do not leave even a single compound from the tables and in-text examples.

Name reactions: Important name reactions which have been asked previously are

Sandmeyer reaction, Williamson synthesis, Riemer-Tiemann reaction, Kolbes reaction, Aldol Condensation, Cannizzaro Reaction, Clemmensen Reduction reaction, Hoffmann

Bromamide reaction, Coupling reaction. So,we advise you to revise these reactions.

Distinction test: The distinction tests are usually asked between:

Aliphatic and aromatic compounds

Compounds having two different functional groups

Compounds having same functional group but different arrangement of atoms (e.g., 1,

2, 3)

Steps for attempting these questions

Step - I: See how many marks are allotted to the question. Remember, 1 mark is for 1 test.

Step II: Write the structural formulae of both the compounds.

Step III: See where the two structures differ in. Step IV: Recall the reactions which you have studied.

Step V: Apply those reactions in the compounds keeping in mind the skeletal structure they differ in.

Conversions: Conversion based questions are surely going to come in exams. Remember

there can be multiple steps to reach the final product but the shortest and feasible steps

have to be written in the answer-sheet.

Please note CBSE has yet not asked any conversion which consist of more than 3-steps.

Steps for attempting these questions Step - I: Read the question very carefully.

Step - II: Write the starting compound on the left hand side and the final compound on the right

hand side.

Step III: See where do the two structure differ in. (They mostly differ either in functional groups, number of carbon atoms or both)

Step IV: Recall the reactions which you have studied. Step V: Apply those reactions in initial compound so as to reach to the final compound.

Expected areas from where questions can come in 2012

Unit Expected areas from where questions can be asked in 2013

examination

Haloalkanes and

Haloarenes

IUPAC Nomenclature, SN1 and SN2 reaction (Question: Which

compound undergoes faster reaction?), DDT, Iodoform

Alcohols, Phenols and

Ethers

IUPAC Nomenclature, Conversions, Alcohols - Boiling points

and solubilities, Phenols-Acidic properties, Difference in the

boiling points of ethers and alcohols, Williamson reaction,

Reimer-Tiemann reaction

Aldehydes, Ketones and

CarboxylicAcids

IUPAC Nomenclature, Nucleophilic addition on carbonyl carbon,

Aldol Condensation, Cannizzaro reaction, Clemmensen reduction

reaction, Acidity of carboxylic acids (Question: Arrange the

following compounds in increasing/ decreasing order of their

acidic trends.), Distinction tests, Conversions

Amines

IUPAC Nomenclature, Basicities of amines (Question: Arrange

the following amines in increasing/ decreasing order of their

basic strengths.), Hoffmann Bromamide reaction, Coupling

reaction, Aniline -Insoluble in water and does not undergo Friedel

Crafts reaction

Biomolecules

Glucose open chain and cyclic structure (Question: Why was the

open chain structure of glucose unable to explain its properties?),

Proteins-Primary, secondary, tertiary and quarternery structures,

Vitamins - Sources and deficiency disease - table 4.3, nucleosides

and nucleotides

Polymers Elastomer, thermoplastic and thermosetting polymer, Rubber,

Nylon 6, nylon 6,6, teflon, bakelite, Buna-N

Chemistry in Everyday Life

Detergents, Food preservatives, Enzymes, Antifertility drugs,

Analgesics, Artificial sweetening agents, biodegradable and non-

biodegradable detergents

To help all you students in this last stage of preparation, we are providing Conversion Schemes

, Distinction Tests, Name Reaction List and Name Reaction in Detail.

Follow these simple but smart ways and give your 100 % in the examination.

Best of Luck!

Team Meritnation

10 comments March 9th, 2013

Coordination Compounds (Chemistry Class XII)

Some important terms:

Coordination Compounds Complex compounds in which the transition metal atoms are bound to a number of anions or neutral molecules

Coordination Entity- Constitutes a central metal atom or ion bonded to a fixed number

of ions or molecules. Example: [CoCl3(NH3)3] is a coordination entity

Central Atom or Ion- The atom or ion to which a fixed number of ions/groups are

bound in a definite geometrical arrangement around it in a coordination entity

Ligands- Ions or molecules bound to the central metal atom or ion in a coordination

entity

Coordination Number- Number of ligand-donor atoms bonded directly to the metal

Coordination Sphere- The central atom or ion and the ligands attached to it are enclosed

in square brackets, which are collectively known as the coordination spheres.

Coordination Polyhedron- The spatial arrangement of the ligand atoms which are

directly attached to the central atom or ion

Oxidation Number of Central Atom- The charge an atom would carry if all the ligands

are removed along with the electron pairs that are shared with the central atom

Homoleptic complexes: Complexes in which the metal is bound to only one kind of

donor group. Example: [Co(NH3)6]3+

Heteroleptic complexes: Complexes in which the metal is bound to more than one kind

of donor groups. For example: [Co(NH3)4Cl2]+

Theories related to coordination compounds:

Werners theory: In coordination compounds, there are two types of linkages (valences) primary and secondary. The primary valences are ionisable, and are satisfied by negative ions. The secondary valences are non-ionisable, and are satisfied by negative

ions or neutral molecules. The secondary valence is equal to the coordination number of a

metal, and remains fixed for a metal. Different coordination numbers have characteristic

spatial arrangement of ions or groups bound by the secondary linkages.

Valence bond theory: The metal atom or ion under the influence of ligands can use its

(n1)d, ns, np or ns, np, nd orbitals for hybridisation, to yield a set of equivalent orbitals of definite geometry such as octahedral, tetrahedral, square planar, and so on. These

hybridised orbitals are allowed to overlap with ligand orbitals that can donate electron

pairs for bonding.

Crystal-field theory: An electrostatic model which considers the metalligand bond to be ionic, and arises purely from the electrostatic interaction between the metal ion and the

ligands. Ligands are treated as point charges in the case of anions, or dipoles in the case

of neutral molecules. The five d-orbitals in an isolated gaseous metal atom/ ion are

degenerate (i.e., have the same energy). Due to the negative fields of the ligands (either

anions or the negative ends of dipolar molecules), the degeneracy of the d-orbitals is

lifted, resulting in the splitting of the d-orbitals.

Coordination compounds:

Features Coordination compounds

Formula writing Central atom is listed first.

The ligands are then listed in the alphabetical order.

Polydentate ligands are also listed in the alphabetical order.

The formula of the entire coordination entity is enclosed in square

brackets.

Ligand abbreviations and formulas for polyatomic ligands are

enclosed in parentheses.

For the charged coordination entity, the charge is indicated outside the

square brackets, as a right superscript, with the number before the

sign.

The charge of the cation(s) is balanced by the charge of the anion(s).

Nomenclature The cation is named first in both positively and negatively charged

coordination entities.

The ligands are named in alphabetical order before the name of the

central atom/ion.

Names of the anionic ligands end in o and those of neutral and cation ligands are the same.

To indicate the number of the individual ligands, the prefixes mono, di, tri, etc., are used. If these prefixes are present in the names of ligands, then the terms bis, tris, tetrakis, etc., are used.

Oxidation state of the metal is indicated by a Roman numeral in

parentheses.

If the complex ion is cation, then the metal is named as the element.

If the complex ion is anion, then the metal is named with ate ending.

The neutral complex molecule is named as the complex cation.

Isomerism Stereoisomerism

1. Geometrical- Due to different possible geometrical arrangement of ligands

2. Optical- Due to chirality.

Structural isomerism

1. Linkage- Only with ambidentate ligand 2. Coordination- Interchange of ligands between cationic and anionic

entities of different metal ions present in the complex

Ionization- The counter ion in the complex salt is itself a potential

ligand and can displace a ligand, which can then become the counter

ion

Solvate- Water is involved as a solvent

Magnetic properties Complexes with unpaired electron(s) in the orbitals are paramagnetic.

Complexes with no unpaired electron(s) in the orbitals (i.e., all the

electrons are paired) are diamagnetic.

Colour The colour of the coordination compounds is attributed to dd transition of

electrons. In the absence of ligand, crystal-field splitting does not occur;

hence, the substance is colourless.

Stability The stability of a complex in a solution refers to the degree of association

between the two species involved in the state of equilibrium. Stability can be

expressed quantitatively in terms of stability constant or formation constant.

Questions that were asked previously:

Q. Name the following coordination entities and describe their structure: (2012 Set 3)

(i) [Fe(CN)6]4-

(ii) [Cr(NH3)4Cl2]+

(iii) [Ni(CN)4]2-

(Atomic numbers: Fe-26, Cr-24, Ni-28)

Q. Write the name, stereochemistry and magnetic behavior of the following: (2011 Set 1)

(Atomic number: Mn-25, Co-27, Ni-28)

(i) K4[Mn(CN)6]

(ii) [Co(NH3)5Cl]Cl2

(iii) K2[Ni(CN)4]

Q. Name the following coordination compounds according to the IUPAC system of

nomenclature: (2010 Set 3)

(i) [Co(NH3)4(H2O)Cl]Cl2

(ii) [CrCl2(en)2]

Best of luck,

Team Meritnation!


d- and f-Block Elements (Chemistry Class XII)

d-Block elements:

General outer electronic configuration: (n -1)d1-10

ns1-2

Generally known as: transition elements/ transition metals

S.

No.

Properties Trends Reason

1 Melting and

boiling point

First transition series are lower than

those of the heavier transition

elements.

Occurrence of stronger metallic

bonding (M-M bonding) in heavier

metals

2 Atomic and ionic

sizes

The atomic sizes of the elements of

the first transition series are smaller

than those of the corresponding

heavier elements.

Increase in nuclear charge and

number of electrons.

The atomic sizes of the elements in

the third transition series are

virtually the same as those of the

corresponding members in the

second transition series.

Lanthanoid contraction

3 Ionisation

Enthalpies

The first ionisation enthalpies of the

third transition series are higher

than those of the first and second

transition series.

Poor shielding effect of 4f electrons

in the third transition series

4 Oxidation states They show variable oxidation

states.

Participation of ns and (n-1)d

electrons in bonding

5 Chemical

reactivity

Many of the transition metals are

electropositive while few are noble.

Presence of empty d-orbitals (as

they can accept electrons)

6 Magnetic

properties

Some metals are paramagnetic

while some are diamagnetic. It

depends on number of electrons.

Magnetic moment increases with

increase in number of electrons

7 Formation of

Coloured Ions

All metals form coloured

compounds.

d-d transition

8 Formation of

Complex

Compounds

Transition metals form a large

number of complex compounds

Comparatively smaller size of metal

ions, high ionic charges and

availability of d-orbitals for bond

formation

9 Catalytic

Properties

Transition metals and their

compounds are known for their

catalytic activity

They can lend electrons or

withdraw electrons from the

reagent, depending on the nature of

the reaction

10 Alloy Formation Alloys are readily formed by these

metals

Similar radii

11 Formation of

Interstitial

Compounds

They form interstitial compounds

with hydrogen.

Hydrogen occupies interstitial sites

in the metal lattice without

changing the type of the lattice

f-Block elements:

General outer electronic configuration: 4f1-14

6s2

Generally known as: inner transition elements


Atomic and ionic

radii

There is a gradual decrease in

atomic and ionic radii of

Lanthanoids.

Lanthanoid contraction

Oxidation states The lanthanoids exhibit mainly +3

oxidation state.

Actinoid: These are the radioactive elements.


Atomic and ionic

radii

There is a gradual decrease in atomic

and ionic radii of actinoids .

Due to actinoid contraction

Oxidation states There is a gradual decrease in atomic

and ionic radii of actinoids. Exhibit

mainly +3 oxidation state.

5f, 6d, and 7s subshells are of

comparable energies.

Ionisation enthalpy Lower ionisation enthalpies 5f electrons are less effectively

shielded than 4f electrons.

Magnetic property Paramagnetic Presence of unpaired electrons.

Lanthanoid Contraction: The steady decrease in the atomic and ionic radii of the transition

metals as the atomic number increases is known as lanthanoid contraction. This is because of

filling of 4f orbitals before the 5d orbitals. This contraction in size is quite regular.

Actinoid Contraction: The gradual decrease in the ionic radii with the increase in atomic no. is

called actinoid contraction. It is due to the imperfect shielding of one 5f electron by the other in

the same subshell.

Topics/ Questions that were asked previously

Variable oxidation states of transition elements (2007, 2008)

Atomic size of transition metals (2012)

Q. There is hardly any increase in atomic size with increasing atomic number in a series of

transition metals? (2012 Set 3)

Formation of coloured ions by transition metal ions (2007, 2010)

Lanthanoid contraction (2007, 2008, 2009)

Oxidation states of actinoids (2009, 2011, 2012 Set 3)

Q. Actinides exhibit a much larger number of oxidation states than the lanthanoids? (2012 Set 3)

Q. With the same d-orbital configuration (d4), Cr

2+ is a reducing agent while Mn

3+ is an

oxidizing agent? (2012 Set 3)

NCERT questions which have been asked previously

Page Question Number Year

211 Example 8.1 2010

220 Example 8.7 2010

220 Intext question 8.6 2010

232 Intext question 8.10 2009, 2008

234 Exercise-8.7 2007

- 8.11 (ii) 2008

- 8.11 (iii) 2007, 2010

- 8.11 (iv) 2008

- 8.21 (i) 2009, 2012

Best of luck,

Team Meritnation!


p-Block Elements (Class XII Chemistry)

Inert pair effect: Inertness of s subshell electrons (i.e. ns2) towards bond formation. As we

move down the group, the lower oxidation state gets stabilised.

Q. Which of the two is more stable? SbCl5 or SbCl3

Q. Why is Bi (V) a stronger oxidant than Sb (V)? (2009 set 1)

Q. The stability of + 5 oxidation state decreases down the group in group 15 of the periodic

table. (2010 Set 3)

Q. Tendency to form pentahalides decreases down the group in group 15 of the periodic

table (2010 Set 3)

Disproportionation: Element in a particular oxidation state undergoes self-oxidation and self-

reduction.

Q. Can HNO3 and H3PO4 undergo disproportionation reaction?

Q. Does hydrolysis of XeF6 lead to disproportionation reaction?

Non-metallic hydrides-Bond dissociation enthalpy and basicity of hydrides decreases down the

group, Reducing character of hydrides increases down the group, Smaller size and inavailability

of d-orbitals affect basic strength

Q. Ammonia is a stronger base than phosphine. (2008 Set 1)

Q. The acidic strength decreases in the order HCl > H2S > PH3 (2010 Set 3)

Q. Which is the stronger acid in aqueous solution? HF or HCl

Q. Ammonia has higher boiling point than phosphine. Explain

Q. Bond angle in phosphine is lesser than ammonia. Explain

Q. H2O is liquid but H2S is gas. Explain

Q. Oxygen is a gas but sulphur is a solid? ( 2012 Set 3)

Q. All the bonds in SF4 are not equivivalent. (2012 Set 3)

Colour of halogen compounds-Halogen absorbs radiations in visible region which excites

electrons to higher energy region, so the amount of energy required for excitation is different for

each halogen.

Q. The halogens are coloured, why? (2012 Set 3)

Non-metallic halides-Hexa halides of elements are stable owing to sterically protected six halide

atoms, Covalent character-Polarising power: Charge/ radius ionic character is opposite of

covalent character

Q. NF3 is an exothermic compound but NCl3 is endothermic compound. (2012 Set 3)

Q. Why are pentahalides more covalent than trihalides?

Q. SF6 is kinetically an inert substance. (2011 Set 1)

Q. Solid phosphorus pentachloride behaves as an ionic compound. (2010 Set 3)

Q. SF4 is easily hydrolysed whereas SF6 is not easily hydrolysed. (2009 Set 1)

Catenation: This self-linking property is due to higher bond strength

Q. Sulphur has greater tendency for catenation than oxygen. (2011 Set 3, 2012 Set 3)

Q. Catenation tendency is weaker in nitrogen than phosphorus. Explain (2012 Set 3)

Q. The tendency of catenation decreases down the group. Explain

Interhalogen compounds: Two or more different halogen atoms reacting with each other to

form compounds.

Q. Interhalogen compounds are strong oxidising agents. (2007, Set 1)

Q. In general interhalogen compounds are more recative than halogens. Why?

Q. Why ICl is more reactive than I2? (NCERT, Intext 7.31, 2012 Set 3)

Q. ClF3 molecule has a T-shaped structure and not a trigonal planar one. (2010, Set 3)

Structures of Oxoacids: phosphorus (2007), sulphur (2007),

Structures of Fluoride: sulphur (2008), xenon (2008, 2009), bromine (2009)

Interhalogen compounds (2007)

Basicity of group 15 elements (2008, 2009)

1. Structures of PCl5, H2SO3, H2SO4, H2S2O8, H2S2O7, HOCl, HClO2, HClO3, HClO4, N2O5, XeOF4

2. Complete the following reaction: o P4 + NaOH + H2O o P4 + SO2Cl2 o POCl3 + H2O o KMnO4 + HCl o NaOH + Cl2 o Cu + HNO3 (dil) o XeF4 + O2F2

3. Conceptual questions:

NF3 is an exothermic compound whereas NCl3 is not.

NH3 is a stronger base than PH3. Why?

Arrange the following in order of the indicated property:

o F2, Cl2, Br2, I2 in increasing order of bond dissociation enthalpy

o HF, HCl, HBr, HI in increasing order of acidic strength

o NH3, PH3, AsH3, SbH3, BiH3 in increasing order of basic strength

What are interhalogen compounds?

mastering organic chemistry and inorganic

Documents