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Unit 1Some Basic Concepts of Chemistry
Chemistry is the science of molecules and their
transformations. It is the science not so much of the one
hundred elements but of the infinite variety of molecules
After studying this unit, you will be that may be built from them.
able to
• appreciate the contribution of India Roald Hoffmann
in the development of chemistry
understand the role of chemistry
in different spheres of life; Science can be viewed as a continuing human effort to
• explain the characteristics of three systematise knowledge for describing and understanding
states of matter; nature. You have learnt in your previous classes that we
• classify different substances come across diverse substances present in nature and
into elements, compounds and changes in them in daily life. Curd formation from milk,
mixtures;
formation of vinegar from sugarcane juice on keeping
• use scientific notations and for prolonged time and rusting of iron are some of the
determine significant figures;
examples of changes which we come across many times.
• differentiate between precision and
For the sake of convenience, science is sub-divided into
accuracy;
various disciplines: chemistry, physics, biology, geology,
• define SI base units and convert
etc. The branch of science that studies the preparation,
physical quantities from one
system of units to another; properties, structure and reactions of material substances
• explain various laws of chemical
is called chemistry.
combination; Development of chemistry
• appreciate significance of atomic Chemistry, as we understand it today, is not a very old
mass, average atomic mass,
discipline. Chemistry was not studied for its own sake, rather
molecular mass and formula mass;
it came up as a result of search for two interesting things:
• describe the terms – mole and
molar mass;
i. Philosopher’s stone (Paras) which would convert
all baser metals e.g., iron and copper into gold.
• calculate the mass per cent of
component elements constituting
ii. ‘Elexir of life’ which would grant immortality.
a compound; People in ancient India, already had the knowledge of
• determine empirical formula and many scientific phenomenon much before the advent of
molecular formula for a compound modern science. They applied that knowledge in various
from the given experimental data; walks of life. Chemistry developed mainly in the form
and of Alchemy and Iatrochemistry during 1300-1600 CE.
• perform the stoichiometric Modern chemistry took shape in the 18th century Europe,
calculations. after a few centuries of alchemical traditions which were
introduced in Europe by the Arabs.
Rationalised 2023-24
Unit 1.indd 1 9/9/2022
, 2 chemistry
Other cultures – especially the Chinese be shown to agree with modern scientific
and the Indian – had their own alchemical findings. Copper utensils, iron, gold, silver
traditions. These included much knowledge of ornaments and terracotta discs and painted
chemical processes and techniques. grey pottery have been found in many
In ancient India, chemistry was called archaeological sites in north India. Sushruta
Rasayan Shastra, Rastantra, Ras Kriya or Samhita explains the importance of Alkalies.
Rasvidya. It included metallurgy, medicine, The Charaka Samhita mentions ancient
manufacture of cosmetics, glass, dyes, etc. indians who knew how to prepare sulphuric
Systematic excavations at Mohenjodaro in acid, nitric acid and oxides of copper, tin and
Sindh and Harappa in Punjab prove that the zinc; the sulphates of copper, zinc and iron
story of development of chemistry in India
and the carbonates of lead and iron.
is very old. Archaeological findings show
that baked bricks were used in construction Rasopanishada describes the preparation
work. It shows the mass production of of gunpowder mixture. Tamil texts also
pottery, which can be regarded as the earliest describe the preparation of fireworks using
chemical process, in which materials were sulphur, charcoal, saltpetre (i.e., potassium
mixed, moulded and subjected to heat by nitrate), mercury, camphor, etc.
using fire to achieve desirable qualities. Nagarjuna was a great Indian scientist. He
Remains of glazed pottery have been found in was a reputed chemist, an alchemist and a
Mohenjodaro. Gypsum cement has been used metallurgist. His work Rasratnakar deals with
in the construction work. It contains lime, the formulation of mercury compounds. He
sand and traces of CaCO3. Harappans made has also discussed methods for the extraction
faience, a sort of glass which was used in of metals, like gold, silver, tin and copper. A
ornaments. They melted and forged a variety book, Rsarnavam, appeared around 800 CE.
of objects from metals, such as lead, silver,
It discusses the uses of various furnaces,
gold and copper. They improved the hardness
ovens and crucibles for different purposes. It
of copper for making artefacts by using tin
describes methods by which metals could be
and arsenic. A number of glass objects were
found in Maski in South India (1000–900 identified by flame colour.
BCE), and Hastinapur and Taxila in North Chakrapani discovered mercury sulphide.
India (1000–200 BCE). Glass and glazes were The credit for inventing soap also goes to him.
coloured by addition of colouring agents like He used mustard oil and some alkalies as
metal oxides. ingredients for making soap. Indians began
Copper metallurgy in India dates back to making soaps in the 18th century CE. Oil of
the beginning of chalcolithic cultures in the Eranda and seeds of Mahua plant and calcium
subcontinent. There are much archeological carbonate were used for making soap.
evidences to support the view that technologies The paintings found on the walls of Ajanta
for extraction of copper and iron were and Ellora, which look fresh even after ages,
developed indigenously. testify to a high level of science achieved in
According to Rigveda, tanning of leather ancient India. Varähmihir’s Brihat Samhita is
and dying of cotton were practised during a sort of encyclopaedia, which was composed
1000–400 BCE. The golden gloss of the in the sixth century CE. It informs about the
black polished ware of northen India could preparation of glutinous material to be applied
not be replicated and is still a chemical on walls and roofs of houses and temples. It
mystery. These wares indicate the mastery was prepared entirely from extracts of various
with which kiln temperatures could be plants, fruits, seeds and barks, which were
controlled. Kautilya’s Arthashastra describes concentrated by boiling, and then, treated
the production of salt from sea. with various resins. It will be interesting to
A vast number of statements and material test such materials scientifically and assess
described in the ancient Vedic literature can them for use.
Rationalised 2023-24
Unit 1.indd 2 9/9/2022
, Some Basic Concepts of Chemistry 3
A number of classical texts, like forces cause interaction between them. He
Atharvaveda (1000 BCE) mention some conceptualised this theory around 2500 years
dye stuff, the material used were turmeric, before John Dalton (1766-1844).
madder, sunflower, orpiment, cochineal and Charaka Samhita is the oldest Ayurvedic
lac. Some other substances having tinting epic of India. It describes the treatment of
property were kamplcica, pattanga and jatuka. diseases. The concept of reduction of particle
Varähmihir’s Brihat Samhita gives size of metals is clearly discussed in Charaka
references to perfumes and cosmetics. Samhita. Extreme reduction of particle size is
Recipes for hair dying were made from plants, termed as nanotechnology. Charaka Samhita
like indigo and minerals like iron power, describes the use of bhasma of metals in the
black iron or steel and acidic extracts of sour treatment of ailments. Now-a-days, it has
rice gruel. Gandhayukli describes recipes been proved that bhasmas have nanoparticles
for making scents, mouth perfumes, bath of metals.
powders, incense and talcum power. After the decline of alchemy, Iatrochemistry
Paper was known to India in the 17th reached a steady state, but it too declined due
century as account of Chinese traveller I-tsing to the introduction and practise of western
describes. Excavations at Taxila indicate that medicinal system in the 20th century. During
ink was used in India from the fourth century. this period of stagnation, pharmaceutical
Colours of ink were made from chalk, red lead industry based on Ayurveda continued to
and minimum. exist, but it too declined gradually. It took
It seems that the process of fermentation about 100-150 years for Indians to learn
was well-known to Indians. Vedas and and adopt new techniques. During this time,
Kautilya’s Arthashastra mention about foreign products poured in. As a result,
many types of liquors. Charaka Samhita also indigenous traditional techniques gradually
mentions ingredients, such as barks of plants, declined. Modern science appeared in Indian
stem, flowers, leaves, woods, cereals, fruits scene in the later part of the nineteenth
and sugarcane for making Asavas. century. By the mid-nineteenth century,
European scientists started coming to India
The concept that matter is ultimately
and modern chemistry started growing.
made of indivisible building blocks, appeared
in India a few centuries BCE as a part of From the above discussion, you have learnt
philosophical speculations. Acharya Kanda, that chemistry deals with the composition,
born in 600 BCE, originally known by the structure, properties and interection of matter
name Kashyap, was the first proponent and is of much use to human beings in daily
of the ‘atomic theory’. He formulated the life. These aspects can be best described and
theory of very small indivisible particles, understood in terms of basic constituents of
which he named ‘Paramãnu’ (comparable matter that are atoms and molecules. That
to atoms). He authored the text Vaiseshika is why, chemistry is also called the science of
Sutras. According to him, all substances are atoms and molecules. Can we see, weigh and
aggregated form of smaller units called atoms perceive these entities (atoms and molecules)?
(Paramãnu), which are eternal, indestructible, Is it possible to count the number of atoms
spherical, suprasensible and in motion in and molecules in a given mass of matter and
the original state. He explained that this have a quantitative relationship between the
individual entity cannot be sensed through mass and the number of these particles?
any human organ. Kanda added that there We will get the answer of some of these
are varieties of atoms that are as different as questions in this Unit. We will further describe
the different classes of substances. He said how physical properties of matter can be
these (Paramãnu) could form pairs or triplets, quantitatively described using numerical
among other combinations and unseen values with suitable units.
Rationalised 2023-24
Unit 1.indd 3 9/9/2022
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