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M Prakash Institute Std IX- 2Yrs Chemistry

L1 Scope of Chemistry
Chemistry is a branch of Physical science that mainly studies
1. The structure and behavior of atoms (elements)
2. The composition and properties of compounds
3. The reactions between substances and the energy exchange
4. The laws of chemical combination.
Chemistry is the science of atoms, involving an understanding of
why they possess certain characteristic qualities and why these
qualities dictate the behavior of atoms when they come together.
All properties of material substances are the inevitable result of
the kind of atoms and the manner in which they are attached and
assembled. All chemical change involves a rearrangement of atoms.
According to Linus Pauling, Chemistry is the science of substances,
their properties, their structure and their transformations. All ob-
jects in this universe are composed of matter. Most of these objects
are visible (solids and liquids) but some are invisible. The matter
ofwhich a physical body is formed is known as a ‘substance’. Iron,
sand, stone, glass, water, copper,plastics, etc. are all different types
of substances. Today we know more than two million substances.
Chemistry is termed as material science because it is concerned
with all material substances such as air, water, rocks, minerals,
plants, animals including human being, the earth, and other plan-
ets.
Chemistry in day to day life:
Chemistry is a subject which touches almost every aspect of our
life, our culture and our environment. It has changed our civiliza-
tion to a great extent. The present day chemistry has provided
man with more comforts for a healthier and happier life. A large
number of materials, which we use these days, were unknown at the
beginning of twentieth century. Polymers, synthetic fibres, chemi-
cal fertilizers, drugs, cosmetics,fuels, glass, ceramics and paints,etc.
have revolutionized living standards.
Two gifts of Modern Chemistry are Glass and Plastics.
Plastics: These include polythene (used for packaging, household
articles), PVC (Poly vinyl chloride) (used for making pipes, tubes,
etc.),bakelite, etc.
Glass: It is made from Silica, Sodium carbonate and other con-
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stituents. Mainly used for glassware, laboratory apparatus, optical

glass (for lenses,prisms,etc.), glass wool (for fireproof clothing,) etc.
The twentieth century is regarded as an active era of chemistry.

Branches of Chemistry
Inorganic Chemistry:
A major branch of Chemistry that studies all substances except
hydrocarbons and their derivatives. Regarding the importance of
inorganic chemistry.
An American inorganic chemist, R.T. Sanderson has written:“ In-
organic chemistry (is) the only discipline within Chemistry that
examines specifically the differences among all the different kinds
of atoms”.
It covers a broad range of subjects, among which are atomic struc-
ture, crystallography, chemical bonding, coordination compounds,
acid-base reactions, ceramics, and the various subdivisions of elec-
trochemistry (electrolysis, battery science, corrosion, semi conduc-
tion, etc.).
Some inorganic compounds used in our day to day life are:
(i) Water(H2 O): As much as 70 percent of an adult human’s body
weight is water. Water is also a universal solvent. Many compounds
such as common salt, sugar are soluble in it.
(ii) Common Salt(NaCl): It is one of the components of table salt.
Iodized common salt is essential for human body.
Can you tell, how exactly is iodized salt important to human body?
(iii) Gases: Gases such as oxygen (O2 ⇒ required for breathing),
nitrogen (N2 ⇒ required for cooling purposes in metal processing in-
dustry), carbon dioxide (CO2 ⇒ used in fire extinguisher), chlorine
(Cl2 ⇒ used as a disinfectant sue to its bacteria killing property)
etc. are present in more or less quantity in atmosphere.
Can you tell, what is the % composition of the gases in atmosphere?
(iv) Limestone and marble (CaCO3 ): Useful in construction, man-
ufacture of glass, cement, to produce CO2 gas in laboratories, etc.
(v) Gypsum (Hydrated Calcium Sulphate, CaSO4 .2H2 O): Used to
neutralise soil, prepare plaster of paris (CaSO4 .1/2H2 O).
(v) Blue vitriol (CuSO4 .5H2 O): Useful in electroplating, as a fungi-
cide,etc.
(vii) Sand (SiO2 ): Useful in the manufacture of glass and cement.
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Organic Chemistry:
‘Organic’ substances were initially thought to be the substances
naturally present in living organisms only (e.g.cellulose, fats, car-
bohydrates,etc.), hence the word. Today we have a lot of organic
compounds prepared in laboratories.
This is a major branch of chemistry which studies all compounds of
carbon except such compounds as the carbon monoxide (CO), car-
bon dioxide (CO2 ); metallic cyanides (e.g., Potassium Cyanide⇒KCN),
metal carbonates (e.g. calcium carbonate ⇒ CaCO3 , Magnesium
Carbonate ⇒ MgCO3 ), metal bicarbonates (e.g. Sodium bicarbonate⇒
NaHCO3 , Potassium bicarbonate⇒KHCO3 ), carbonyls complexes
(e.g. Carbonyl sulfide⇒ COS) etc.
The total number of organic compounds is indeterminate, but some
6,000,000 have been identified and named. Also everyday new com-
pounds get added due to continuous research.
Petroleum and coal are two wonder organic substances. The Petroleum
products include: plastics, synthetic rubber, explosives, synthetic
fibres, perfumery, varnishes, dyes, liquid fuels, home gas, alcohol,
paraffin, lubricants, aspahlt, etc.
The products from Coal(carbon) are : Coal → Coke → Calcium
carbide → Acetylene → Acetic acid, plastics;
Coal → Coal pitch → tar, aniline,dyes, benzene, naphthalene;
Coal → Coal pitch → toluene → saccharin
Coal→ home gas, phenol, plastics,etc.
Important areas of organic chemistry include polymerization, hy-
drogenation, isomerization, fermentation, photochemistry, and stere-
ochemistry.
There is no sharp dividing line between organic and inorganic chem-
istry, for the two often tend to overlap. For example, chemical
bonding applies to both disciplines, electrochemistry and acid-base
reactions have their organic counterparts, catalysts and coordina-
tion compounds may be either organic or inorganic.
Analytical Chemistry
Analytical Chemistry is the subdivision of Chemistry concerned
with identification of materials (qualitative analysis) and with de-
termination of the percentage composition of mixtures or the con-
stituents of a pure compound (quantitative analysis). The gravi-
metric and volumetric (or “wet”) methods (precipitation, titration
etc) are used in laboratories.
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However, faster and more accurate techniques (collectively called

instrumental) have been developed in the last few decades. Among
these are:
(i) Infrared, ultraviolet, and x-ray spectroscopy( where the pres-
ence and amount of a metallic element is indicated by lines in it’s
emission or absorption spectrum),
(ii) Colorimetry, by which the percentage of a substance in solution
is determined by the intensity of it’s colour;
(iii) Chromatography of various types, by which the components of
a liquid or gaseous mixture are determined by passing it through a
column of porous material or on thin layers of finely divided solids.
New and highly sophisticated techniques have been introduced in
recent years, in many cases replacing traditional methods.
Physical Chemistry
Application of the concepts and laws of physics to chemical phe-
nomena in order to describe in quantitative (mathematical) terms
a vast amount of qualitative (observational) information is done in
this branch of Chemistry. The most important concepts of physical
chemistry include
(i) The study of atomic and molecular structure,
(ii) The study of the subatomic fundamental particles of matter,
(iii) Application of thermodynamics to heats of formation of com-
pounds and the heats of chemical reaction,
(iv) The theory of rate processes and chemical equilibria,
(v) Chemical bonding and surface chemistry,
(vi) Electrochemistry .
Although physical chemistry is closely related to both inorganic and
organic chemistry, it is considered a separate discipline.
Nuclear Chemistry:
It is the division of Chemistry dealing with changes in or transfor-
mations of the atomic nucleus. It includes spontaneous and induced
radioactivity, the fission or splitting of nuclei, and their fusion, or
union; also the properties and behavior of the reaction products
and their separation and analysis. The reactions involving nuclei
are usually accompanied by large energy changes, far greater than
those of chemical reactions; that are carried out in nuclear reactors
for electric power production and manufacture of radioactive iso-
topes for medical use.
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Biochemistry:
Originally a subdivision of chemistry but now an independent sci-
ence, biochemistry includes all aspects of chemistry that apply to
living organisms. Thus, photochemistry is directly involved with
photosynthesis and physical chemistry with osmosis- the phenom-
ena that underlie all plant and animal life.
Other important chemical mechanisms that apply directly to living
organisms are nucleic acid and protein constitution and behavior,
which is known to control the mechanism of genetics; colloid chem-
istry, which deals in part with the nature of cell walls, muscles,
collagen, etc; acid-base relations, involved in the pH of body fluids;
and such nutritional components as amino acids, fats, carbohy-
drates, minerals, lipids and vitamins, all of which are essential to
life.
The chemical organization and reproductive behavior of microor-
ganisms (bacteria and viruses) and a large part of agricultural chem-
istry are also included in biochemistry. Particularly active areas of
biochemistry are nucleic acids, cell surfaces (membranes), enzymol-
ogy, peptide hormones, molecular biology, and recombinant DNA.

Green chemistry:
Green chemistry, also called sustainable chemistry, is an area of
chemistry and chemical engineering focused on the designing of
products and processes that minimize the use and generation of
hazardous substances. The overarching goals of green chemistry,
namely, more resource-efficient and inherently safer design of molecules,
materials, products, and processes, can be pursued in a wide range
of contexts.
In 1998, Paul Anastas (who is considered as “father of Green Chem-
istry”) and John C. Warner published a set of principles to guide
the practice of green chemistry. Later on, American Chemical So-
ciety modified them and they are:
1. Inherent Rather Than Circumstantial - Designers need to strive
to ensure that all materials and energy inputs and outputs are as
inherently nonhazardous as possible.
2. Prevention Instead of Treatment - It is better to prevent waste
than to treat or clean up waste after it is formed.
3. Design for Separation - Separation and purification operations
should be designed to minimize energy consumption and materials
use.
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4. Maximize Efficiency - Products, processes, and systems should

be designed to maximize mass, energy, space, and time efficiency.
5. Output-Pulled Versus Input-Pushed - Products, processes, and
systems should be ”output pulled” rather than ”input pushed”
through the use of energy and materials.
6. Conserve Complexity - Embedded entropy and complexity must
be viewed as an investment when making design choices on recycle,
reuse, or beneficial disposition.
7. Durability Rather Than Immortality - Targeted durability, not
immortality, should be a design goal.
8. Meet Need, Minimize Excess - Design for unnecessary capacity
or capability (e.g., ”one size fits all”) solutions should be considered
a design flaw.
9. Minimize Material Diversity - Material diversity in multicom-
ponent products should be minimized to promote disassembly and
value retention.
10. Integrate Material and Energy Flows - Design of products, pro-
cesses, and systems must include integration and interconnectivity
with available energy and materials flows.
11. Design for Commercial ”Afterlife” - Products, processes, and
systems should be designed for performance in a commercial ”af-
terlife.”
12. Renewable Rather Than Depleting - Material and energy in-
puts should be renewable rather than depleting.

Assignment

Q 1. Match the columns:

. A B
1.Organic Chemistry a. Concepts and laws of physics
2. Inorganic Chemistry b. Transformations in nucleus
3. Physical Chemistry c. Carbon compounds
4. Analytical Chemistry d. Living organisms
5. Nuclear Chemistry e. Identification of materials.
6. Biochemistry f. All substances except
. hydrocarbons
Q.2. Define :
(i) Substance (ii) Colorimetry (iii) Chromatography
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Q 3. Give the chemical names of the following :

(i) Limestone (ii) Gypsum (iii) Blue vitriol (iv) Vinegar
Q 4. State the uses of
(i) Glass wool (ii) Gypsum (iii) Calcium carbide
Q.5. What are the twelve principles of green chemistry?

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Reading Material:
(Make sure that you’ve read this before atteding the next lecture.)

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From ancient times philosophers and scientists have always won-

dered what is matter composed of. Many theories were proposed
from time to time.
1. Early atomic theories:
1. a) Greeks: Leucippus (450 BC), Democritus (400 BC), Lu-
cretius (50 BC).
i) Lucretius, described atomism in his De Rerum Natura. He ob-
served that any material is subject to irreversible decay. Through
time, even hard rocks are slowly worn down by drops of water.
Things have the tendency to get mixed up: mix water with soil
and you get mud, that will usually not un-mix by itself. Wood
decays. However, we see in nature and technology that there are
mechanisms to recreate ‘pure’ materials like water, air, metals. The
seed of an oak will grow out into an oak tree, made of similar wood
as historical oak trees, the wood of which has already decayed. The
conclusion is that many properties of materials must derive from
something inside, that will itself never decay, something that stores
for eternity the same inherent, indivisible properties. The basic
question is: why has everything in the world not yet decayed, and
how can exactly the same materials, plants, animals be recreated
again and again?.
Here came the idea of some fundamental particles. ‘tomio’ in greek
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means divisible. Thus ‘atomio’ means something indivisible. Hence

such fundamental particles was called items. These classical ‘atoms’
are nearer to our modern concept of ‘molecule’ than to the atoms
of modern science. The other big point of classical atomism is that
there must be a lot of open space between these ‘atoms’: the void.
Lucretius gives reasonable arguments that the void is absolutely
necessary to explain how gasses and fluids can change shape, flow,
while metals can be molded, without changing the basic material
properties
ii) Atoms are small, indestructible with lot of space between them.
iii) Atoms of different elements differ in size and shape.
iv) Metal atoms are strong with hooks to lock them, liquid atoms
are smooth and slippery, salt atoms are sharp and slash at out
tongue, atoms of air are light and whirling about
1. b) Indian Scene: Kanad (600 BC? or 200 BC?)
i) Many believe it was Kanada who originated the idea that para-
manu (atom) was an indestructible particle of matter. An inter-
esting story states that this theory occurred to him while he was
walking with food in his hand. As he nibbled at the food in his
hand, throwing away the small particles, it occurred to him that
he could not divide the food into further parts and thus the idea of
a matter which cannot be divided further came into existence. He
called that indivisible matter anu, i.e. atom.
ii) Followers of Kanada, considered the atom to be indestructible,
and hence eternal. They believed atoms to be minute objects in-
visible to the naked eye which come into being and vanish in an
instant. Vaiseshikas further held that atoms of same substance com-
bined with each other to produce dvyanuka (biatomic molecules)
and tryanuka (triatomic molecules). Kanada also put forward the
idea that atoms could be combined in various ways to produce
chemical changes in presence of other factors such as heat. He gave
blackening of earthen pot and ripening of fruit as examples of this
phenomenon.
iii) This Indian conception of the atom was developed indepen-
dently and possibly prior (depending on which dates one accepts
for the life of Kanada) to the development of the idea in the Greco-
Roman world. Indian theories about the atom are greatly abstract
and enmeshed in philosophy as they were based on logic and not on
personal experience or experimentation. Thus the Indian theories
lacked an empirical base.