Inorganic Chemistry for the JEE Mains and Advanced

937 Pages·2014·12.361 MB·English

by  K. Rama Rao

Inorganic Chemistry
for the JEE
(Mains and Advanced)
K. Rama Rao
Delhi (cid:31) Chennai
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Copyright © 2013 Dorling Kindersley (India) Pvt. Ltd.
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eISBN 9789332529465

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Contents
Preface v
Chapter 1. Structure of Atom 1.1–1.82
Chapter 2. Periodic Classification 2.1–2.48
Chapter 3. Chemical Bonding 3.1–3.104
Chapter 4. Hydrogen and its Compounds 4.1–4.44
s-BLoCK ELEmEntS
Chapter 5. Group-ia (1): Alkali metals 5.1–5.46
Chapter 6. Group-iia (2): Alkaline Earth metals 6.1–6.38
p-BLoCK ELEmEntS
Chapter 7. Group-iii a (13) Boron Family 7.1–7.56
Chapter 8. Group-iv (a) (14) Carbon Family 8.1–8.56
Chapter 9. Group va (15) nitrogen Family 9.1–9.78
Chapter 10. Group via (16) oxygen Family 10.1–10.54
Chapter 11. Group viia (17) Halogens 11.1–11.52
Chapter 12. Group 18 noble Gases 12.1–12.20
Chapter 13. the d- and f- Block Elements 13.1–13.38
Chapter 14. Coordination Compounds 14.1–14.80
Chapter 15. metallurgy 15.1–15.82
Chapter 16. Qualitative Analysis 16.1–16.42
appendices
hydration, hydrolysis and solubility a.1
strength of acids a.7
atomic Weights a.10
electron affinities a.11
Ionization Energies a.12
Units and Conversion Factors a.15
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Preface
Inorganic Chemistry is an outcome of several years of teaching chemistry to the students preparing for different competitive
examinations. When the thought of bringing out this book came to my mind, three pertinent questions required consideration.
• First, is there really a need to bring out yet another book on the subject ‘inorganic chemistry’ when there are already so
many standard books available in the market?
• Second, how this book would tackle the limitations in the presentation of the subject in case of preparation of different
competitive examinations after the completion of Class XII?
• Third, what must be the right order or sequence of topics so that the preparation will be easier for the students?
I believe that the answer to the first question lies in the rich content offered by this book. While dealing with various topics
of inorganic chemistry, one needs to refer to different books for clarifications on various topics. Naturally, an absence of a one-
stop solution to all the problems is felt by the students. This justifies the need to bring out a book which can serve as a single
source of reference on inorganic chemistry and make learning simpler and facilitate problem-solving.
An analysis of the questions asked in various competitive examinations conducted over the last few years was done. It
was seen that the knowledge required to answer the questions is much more than what is offered at the Class XII level. In fact,
a deeper study of the concepts is needed to attempt these questions. This book goes a little deeper into the concepts/topics
included at the Class XII level. This answers the second question mentioned above. Moreover, this analysis also fulfills the
need to study the difficulty level of questions, types of questions and important topics etc., as the sole purpose of this book is to
equip the student with sufficient knowledge to solve multiple-choice questions pertaining to inorganic chemistry. As far as the
third question is concerned, my own personal experience in teaching the subject in a student-friendly manner has been helpful
in planning the sequence in which the topics should be dealt with.
Earlier, the study of inorganic chemistry was thought to be a very complex and elongated process; one requiring the need
to study and remember all the properties and uses of various elements and their compounds thoroughly. But with the passage of
time, the requirements of teachers and students necessitated the need to deal with each topic in a logical manner. For instance,
there has been a steady infiltration of physical chemistry into inorganic chemistry and it has resulted in the subject being made
rigorous and more comprehensive for studying as compared to the past scenario. As such, it is a futile attempt if one writes a
book on inorganic chemistry without laying stress on structural and energy considerations which are the two kingpins upon
which a satisfactory development of the subject rests. The Class XII syllabus tends to reflect this trend. For this purpose,
concepts such as enthalpy, entropy, free energy changes, equilibrium and equilibrium constant, acid base etc., are explicitly
touched upon wherever necessary. In explaining the stability and solubility of inorganic compounds such as carbonates, sul-
phates, halides, oxides, hydroxides, etc., the concept of thermodynamics is aptly used. Similarly, an attempt has been made
to explain the trend in solubility of inorganic compounds based on the acid base theory and thermodynamic data. Mainly, the
focus is on explaining the different aspects with a logical approach so that students may retain a steady interest in the subject.
The book goes beyond the immediate needs of the existing Class XII syllabus and fulfills all the requirements of a prepara-
tory tool required to attempt questions asked in various competitive examinations. I hope that not only students would benefit
from this book but teachers would also find it as a valuable resource for referring to the explanations of various concepts in a
simple and detailed manner.
I am grateful to all those who directly or indirectly encouraged me to author this book. I am also very grateful to the staff of
Pearson Education, especially Rajesh Shetty, Bhupesh Sharma and Vamanan Namboodiri, for their continuous encouragement
and hard work in bringing out this book in this fascinating manner.
Good Luck!
K. Rama Rao
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1
r
e
t
p
a
h
C
Structure of Atom
T
he universe is a concourse of atoms.
Marcus Aurelius
1.1 iNTRODUCTiON
John Dalton was born in England in 1766. His
The introduction of atomic theory by John Dalton early in the
family was poor, and his formal education stopped
nineteenth century marks the beginning of modern era in
when he was eleven years old. He became a school
the research initiatives in the field of Chemistry. The virtue
teacher. He was colour blind. His appearance and
of Dalton’s theory was not that it was new or original, for
manners were awkward, he spoke with difficulty in
theories of atoms are older than the science of chemistry,
public. As an experiment he was clumsy and slow.
but that it represented the first attempt to place the cor-
He had few, if any outward marks of genius.
puscular concept of matter upon a quantitative basis.
In 1808, Dalton published his celebrated New
The theory of the atomic constitution of matter dates back at
Systems of Chemical Philosophy in a series of publica-
least 2,500 years to the scholars of ancient Greece and early
tions, in which he developed his conception of atoms as
Indian philosophers who were of the view that atoms are
the fundamental building blocks of all matter. It ranks
fundamental building blocks of matter. According to them,
among two greatest of all monuments to human intel-
the continued subdivision of matter would ultimately yield
ligence. No scientific discovery in history has had a
atoms which would not be further divisible. The word
more profund affect on the development of knowledge.
‘atom’ has been derived from the Greek word ‘a-tomio’
Dalton died in 1844. His stature as one of the
which means ‘uncuttable’ or non-divisible. Thus, we
greatest scientists of all time continues to grow.
might say that as far as atomic theory is concerned, Dalton
added nothing new. He simply displayed a unique ability to
crystallize and correlate the nebulous notions of the atomic
Thus, to Dalton, the atoms were solid, hard, impene-
constitution prevalent during the early nineteenth century
trable particles as well as separate, unalterable individuals.
into a few simple quantitative concepts.
Dalton’s ideas of the structure of matter were born out of
considerable amount of subsequent experimental evidence
1.2 ATOmiC TheORy as to the relative masses of substances entering into chemi-
cal combination. Among the experimental results and rela-
The essentials of Dalton’s atomic theory may be summa-
tionship supporting this atomic theory were Gay-Lussac’s
rized in the following postulates:
law of combination of gases by volume, Dalton’s law of
1. All matter is composed of very small particles called atoms.
multiple proportions, Avagadro’s hypothesis that equal vol-
2. Atoms are indestructible. They cannot be subdivided,
umes of gases under the same conditions contain the same
created or destroyed.
number of molecules, Faraday’s laws relating to electrolysis
3. Atoms of the same element are similar to one another
and Berzelius painstaking determination of atomic weights.
and equal in weight.
4. Atoms of different elements have different properties
modern Atomic Theory
and different weights.
5. Chemical combination results from the union of atoms Dalton’s atomic theory assumed that the atoms of elements
in simple numerical proportions. were indivisible and that no particles smaller than atoms
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1.2 Structure of Atom
exist. As a result of brilliant era in experimental physics To vacuum
which began towards the end of the nineteenth century Gas at low pressure pump
extended into the 1930s paved the way for the present
modern atomic theory. These refinements established that Cathode Anode
atoms can be divisible into sub-atomic particles, i.e., elec- − +
trons, protons and neutrons—a concept very different from
that of Dalton. The major problems before the scientists at
that time were
(i) How the sub-atomic particles are arranged within the
atom and why the atoms are stable?
(ii) Why the atoms of one element differ from the atoms High voltage
of another elements in their physical and chemical
Fig 1.1 Cathode ray discharge tube
properties?
(iii) How and why the different atoms combine to form
molecules?
(iv) What is the origin and nature of the characteristics of the charge necessary to deposit one atom of a 1-valent
electromagnetic radiation absorbed or emitted by atoms? element by Stoney in 1891. In 1879, Crookes discov-
ered that when a high voltage is applied to a gas at low
pressure streams of particles, which could communicate
1.3 SUb-ATOmiC PARTiCleS momentum, moved from the cathode to the anode. It did
not seem to matter what gas was used and there was
We know that the atom is composed of three basic sub-atomic
strong evidence to suppose that the particles were com-
particles namely the electron, the proton and the neutron. The
mon to all elements in a very high vacuum they could not
characteristics of these particles are given in Table 1.1.
be detected. The cathode ray discharge tube is shown
It is now known that many more sub-atomic particles
in Fig 1.1.
exist, e.g., the positron, the neutrino, the meson, the hyperon
The properties of the cathode rays are given below:
etc, but in chemistry only those listed in Table 1.1 generally
need to be considered. The discovery of these particles and (i) When a solid metal object is placed in a discharge
the way in which the structure of atom was worked out are tube in their path, a sharp shadow is cast on the end
discussed in this chapter. of the discharge tube, showing that they travel in
straight lines.
(ii) They can be deflected by magnetic and electric fields,
1.3.1 Discovery of electron
the direction of deflection showing that they are neg-
The term ‘electron’ was given to the smallest particle atively charged.
that could carry a negative charge equal in magnitude to (iii) A freely moving paddle wheel, placed in their path, is
set in motion showing that they possess momentum,
i.e., particle nature.
Table 1.1 The three main sub-atomic particles
(iv) They cause many substances to fluoresce, e.g., the
Particle Symbol Mass Charge familiar zinc sulphide coated television tube.
(v) They can penetrate thin sheets of metal.
Electron e 1/1837 of – 4.8 × 10−10 esu
H-atom or 9.109 × or –1.602 × 10−19 J.J. Thomson (1897) extended these experiments and
10−28 g coulombs (–1 unit) determined the velocity of these particles and their charge/
or 9.1×10−31 kg mass ratio as follows.
Proton p 1.008 amu or + 4.8 × 10−10 esu The particles from the cathode were made to pass
1.672 × 10−24 g or + 1.602 × 10−19 through a slit in the anode and then through a second slit.
or 1.672×10−27 kg coulombs (+ 1 unit) They then passed between two aluminium plates spaced
(1 unit) about 5 cm apart and eventually fell onto the end of the
Neutron n 1.0086 amu or No charge tube, producing a well-defined spot. The position of the
1.675 × 10−24 g spot was noted and the magnetic field was then switched
or 1.675 × 10−27 kg on, causing the electron beam to move in a circular arc
(1 unit) while under the influence of this field (Fig 1.2).
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Structure of Atom 1.3
Spot of light
when top plate is
positive
+
Gas at low pressure
Anode (+)
Spot of light
when plate is
not charged
Cathode
(cid:11)(cid:178)(cid:12) Deflecting
plates
(cid:178)
Fluorescent
screen
Fig 1.2 Thomson’s apparatus for determining e/m for the electron
Thomson proposed that the amount of deviation of the Millikan Oil Drop Method
particles from their path in the presence of electrical and
To vacuum pump
magnetic field depends on M
(i) Greater the magnitude of the charge on the particle, −
greater is the interaction with the electric and mag- VVv B
Oil sprayer
netic fields, and thus greater is the deflection. + A
(ii) Lighter the particle, greater the deflection
Oil
(iii) The deflection of electrons from its original path globules
increase in the voltage across the electrodes, or the W1 E W2
strength of the magnetic field. x – Rays
Light
E
By careful and quantitative determination of the mag- 1
netic and electric fields on the motion of the cathode rays,
Thomson was able to determine the value of charge to mass
ratio as Fig 1.3 Millikan’s apparatus for determining the value of
the electronic charge
e
=1.758820×1011C kg−1 (1.1)
m
e
e 1.6022×10−19 C
m is the mass of the electron in kg and e is the m = = (1.2)
e e e/m 1.758820×1011C kg−1
magnitude of the charge on the electron in Coulomb. e
= 9.1094 × 10−31 kg (1.3)
1.3.2 Charge on the electron
Small droplets of oil from an atomiser are blown into a
Thomson’s experiments show electrons to be negatively still thermostated airspace between parallel plates, and the
charged particles. Evidence that electrons were discrete rate of fall of one of these droplets under gravity is observed,
particles was obtained by Millikan by his well known oil from which its weight can be calculated. The airspace is
drop experiment during the years 1910−14. By a series of now ionized with an X-ray beam, enabling the droplets to
very careful experiments Millikan was able to determine pick up charge by collision with the ionized air molecules.
the value − electronic charge, and the mass. Millikan By applying a potential of several thousand volts across the
found the charge on the electron to be −1.6 × 10−19 C. parallel metal plates, the oil droplet can either be speeded
The present-day accepted value for the charge on the elec- up or made to rise, depending upon the direction of the elec-
tron is 1.602 × 10−19 C. When this value for ‘e’ is com- tric field. Since, the speed of the droplet can be related to its
pared with the most modern value of e/m, the mass of the weight, the magnitude of the electric field, and the charge it
electron can be calculated. picks up, the value of the charge can be determined.
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1.4 Structure of Atom
1.3.3 Discovery of Proton 9Be+ 2He→12C +1n
4 4 6 0
If the conduction of electricity, through gases is due to
Where the superscript refers to the atomic mass and
particles, which are similar to those involved during
the subscript refers to the atomic number (the number of
electrolysis, it was to be expected that positive as well as
protons in the nucleus). Notice that a new element, carbon,
negative ones should be involved, and that they would be
emerges from this reaction.
drawn to the cathode. By using a discharge tube contain-
ing a perforated cathode, Goldstein (1886) had observed
the formation of rays (shown to the right of the cathode in 1.4 ATOmiC mODelS
Fig 1.4).
The discovery that atoms contained electrons caused some
J.J. Thomson (1910) measured their charge/mass ratio
consternation. Left to themselves, atoms were known to be
from which he was able to deduce that the particles were
electrically neutral. So, the negative charge of the electrons
positive ions, formed by the loss of electrons from the
had to be balanced by an equal amount of positive charge.
residual gas in the discharge tube. The proton is the small-
The puzzle was to work out how the two types of charges
est positively charged particle equal in magnitude to that
were arranged. To explain this, different atomic models
on the electron and is formed from the hydrogen atom by
were proposed. Two models proposed by J.J. Thomson and
the loss of an electron.
Earnest Rutherford are discussed here though they cannot
H → H+ + e− explain about the stability of atoms.
Unlike cathode rays, the characteristics of posi-
tively charged particles depend upon the nature of the 1.4.1 Thomson model of Atom
gas present in the cathode ray tube. These are positively
charged ions. The charge to mass ratio of these parti-
cles is found to be dependent upon the gas from which “A theory is a tool not a creed.” J.J. Thomson
these originate. Some of the positively charged particles Sir Joseph John Thomson 1856–1940
carry a multiple of the fundamental unit of electrical Thomson’s researches on discharge of electricity
charge. The behaviour of these particles in the magnetic through gases led to the discovery of the electron and
or electric field is opposite to that observed for electron isotopes.
or cathode rays.
In 1898, Sir J.J. Thomson proposed that the electrons
1.3.4 Discovery of Neutron
are embedded in a ball of positive charge (Fig 1.5). This
The neutron proved to be a very elusive particles to track model of the atom was given the name plum pudding or
down and its existence, predicted by Rutherford in 1920, raisin pudding or watermelon. According to this model
was first noticed by Chadwick in 1932. Chadwick was we can assume that just like the seeds of a watermelon are
bombarding the element beryllium with α-particles and embedded within the reddish juicy material, the electrons
noticed a particle of great penetrating power which was are embedded in a ball of positive charge. It is important
unaffected by magnetic and electric fields. It was found to to note that in Thomson’s model, the mass of the atom is
have approximately the same mass as the proton (hydrogen
ion). The reaction is represented as
Perforated cathode
_
+ H e H+
H _ H+
_e Positive rays
H e
H+
Anode
Fig 1.5 The Thomson model of atom. The positive
– charge was imagined as being spread over the entire atom
Fig 1.4 and the electrons were put in this background
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