ARTICLE
AN INTRODUCTION TO THE HISTORY OF CHEMISTRY
N. R. DAS*
The word chemistry originated from the term, chemi or kima, the name of Egypt in Egyptian. The
time period for the history of chemistry covers from ancient history of chemistry to the present. In
earliest civilizations, fire was accepted as a mystical force and the controlled use fire in their
familiar regular practices like cooking, lighting, making of earthen and glass wares, medicines,
wines, metallurgy, armours, etc. eventually resulted in the development of various branches of
chemistry in the later period. The basic chemical hypothesis was first propounded by Aristotle with
his theory of four fundamental elements, fire, earth, water and air, from which everything was
formed as a combination. In medieval alchemy around 300 B. C., the arts of alchemy being
intermingled with magic and occultism proliferated into natural science with the goal of transmuting
cheap metals into precious gold with ‘Philosopher’s Stone’ and of chemical concoction, ‘The Elixir
of Life’, for a longer and cured life. In seventeenth century, Robert Boyle was the first to make a
clear differentiation between alchemy and scientific experimental approach towards matter initiating
the trend of the history of modern chemistry. The pioneering contributions of Antoine Lavoisier
and Jons Berzelius established the subject of chemistry on proper experimental and theoretical
footings of chemical science. In the later period, with important discoveries and rapid advancement
in research and technologies, in general, the subject of chemistry has been expanded into different
broad groups as well as in cross-disciplinary and specialized fields of chemical science depending
on the type and kind of matter being investigated. Chemistry is now a major branch of physical
science.
Introduction
I
n early civilizations, thinkers were those who always
search for the logic regarding the existence of the
surrounding materials and tried to identify the basic
elements comprising the natural substances. The ancient
Greek, Indian, Mayan, Chinese and other philosophies
attempted to postulate appropriate hypothesis for the
existence of the natural materials in solid, liquid or gaseous
phases having different characteristic properties of density,
colour, smell, etc. as well as their changing behaviours in
the prevailing environmental conditions.
In the history of chemistry as early as around 300 B.
C., the regular skilful practices involving various techniques
*
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Former Professor, Saha Institute of Nuclear Physics, 1/AF, Bidhan
Nagar, Kolkata - 700 064, e-mail : [email protected]
of chemistry, medicine, metallurgy, astronomy, philosophy,
astrology and mysticism, as parts of normal behaviour in
different regions of the world, were known as Alchemy.
An alchemist was later designated as a ‘chemist’ and in
describing the activities of the chemists, the suffix ‘-ry’
was added to the word chemist, to assign the subject as
‘chemistry’.
The etymology or the origin of the word chemistry is
much disputed as the science of chemistry has been around
since the prehistoric times. The visions on the composition
and properties of matter were to some extent shared by
both alchemy and chemistry and a blend of these was
presented earlier by the term chymistry. Robert Boyle in
1661 was the first to use the term chymistry to specify the
subject dealing with the material principles of mixed
bodies. According to Christopher Glaser (1663), chymistry
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meant to acquire scientific knowledge of dissolving a
substance, to draw from it another substance of different
composition and to exalt it to a higher perfection. In 1730,
Georg Ernst Stahl was perhaps the first to use the word
chemistry to describe the technique of resolving mixed,
aggregate or compound materials into their principles and
of composing these materials from those principles. JeanBaptiste Dumas in 1837 referred chemistry to deal with
the science concerning the laws and the effects of molecular
forces.
In retrospect, with new discoveries and development
of theories in chemical science, the definition of chemistry
has gradually been modified over the period. For example,
Linus Pauling in 1947 suggested that the chemistry is to
deal with the science of substances involving their structure,
properties and the reactions that change them into other
substances. More recently in 1998, the definition of
chemistry has been broadly modified to mean the study of
matter and the changes it undergoes, as phrased by
Professor Raymond Chang. The subject of chemistry has
now become a major branch of physical science primarily
concerned with atoms, molecules and their interactions and
transformations involving the structure, composition and
properties of matter. With rapid advancement of science,
the subject of chemistry, in the later period, has become
intertwined with the modern topic like thermodynamics,
nuclear science and many other fields of advanced research,
particularly, in occupying an intermediate position between
physics and biology.
In this article, the time span for the History of
Chemistry representing from the ancient period to the
present is chronologically classified into four broad
categories such as Ancient Period of the History of
Chemistry, Medieval Alchemy, Early Chemistry of 17th and
18th Centuries, and Chemistry of 19th Century to the
Present.
Ancient Period of History
The earliest evidence of using metal by humans as free
‘native’ gold has been manifested from the fact that small
amounts of natural gold have been found in Spanish caves
of the late Paleolithic period of around 40,000 B. C. In
ancient Egypt, as early as in 2900 B.C., gold was
considered as precious metal and the metals like silver,
copper, tin which can also be sometimes found native were
used in metal working in the prevailing cultures. Egyptian
weapons made from meteoric iron in about 3000 B.C. were
known as ‘Daggers from Heaven’.
In early societies, the fire that was generally utilized
to transform one substance into another producing heat and
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light was accepted simply as a mystical force. Early
evidence of extractive metallurgy dated fifth and sixth
millennium B. C. involving lead and copper was found in
different archaeological sites in Siberia and of the third
millennium B. C. in Portugal, Spain and United Kingdom.
The controlled use of fire in various aspects of cooking
and habitat lighting; making of glass and earthen wares
like pottery, bricks, glazes; fermentation of beers and wines;
preparation of medicines, soaps, perfumes; extraction of
chemicals from plants; etc. eventually formed the basis for
development of different branches of chemistry in the later
period of around 1000 B. C.
The application of fire for extraction and purification
of metals from ores, production of alloys like bronze,
making of armors and weapons for the armies from superior
alloys, etc. resulted in the initiation of the field of
metallurgy which helped in the development of early human
culture. In the Bronze Age around 3500 B.C., significant
progress in alchemy involving metallurgy was achieved in
ancient India. The Iron Age began with the development
of the method for extraction of metal iron from its ores by
Hittites in about 1200 B.C. Wide varieties of evidences of
early civilizations in different regions of the world
particularly in ancient and medieval kingdoms and empires
of the Middle East, Iran, Egypt, Anatolia (Turkey), Greeks,
Romans, Europe, China, India, Japan, amongst others, have
indicated the cultural developments in this age period. The
new prehistoric discoveries are continuous and ongoing.
The early theory of atomism has been traced back to
ancient Greece and ancient India. The Greek philosophers,
Democritus and Epicurus, around 440 B.C, proclaimed that
the simplest unit of matter is the atom and all matter is
composed of these indivisible and indestructible atoms. The
proclamation was found to be corroborated with the views
of the Indian philosopher, Kanada, the founder of the
Vaisheshika philosophy, around the same time period. In
380 B. C, the Greek thinker, Polybus postulated that the
human body is composed of four humours, the four fluids
of the body, believed to determine the physical and mental
qualities of human. Epicurus around 300 B.C. suggested a
universe of indestructible atoms in which man himself has
the capability of achieving a balanced life.
In early civilizations, the familiar practices of arts or
the skilled techniques were followed without any basic
knowledge or a systematic concept. In 300 B.C., a chemical
hypothesis was first propounded by Aristotle in Greece with
the theory of four fundamental elements, fire (hot and dry),
water (cold and moist), air (hot and moist) and earth (cold
and dry), as presented in Figure 1, in which everything
was considered to be formed as a combination of these
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elements. Empedocles also hinted a hypothesis about the
theory of fundamental elements earlier in 420 B. C. The
Roman poet and philosopher Lucretius in 50 B. C. wrote
‘De Rerum Natura (The Nature of Things)’ which
described the principles of atomism; the nature of mind
and soul; cause of sensation and thought; the development
of the world and explanations for a variety of celestial and
terrestrial phenomena.
Fire
Water
Air
Earth
Figure 1. Symbol of basic alchemy
Medieval Alchemy
The word alchemy was derived from the
Arabic synonym, al-kîmîâ which might have been originated
from the word Chemi or Kimi, the ancient name of Egypt
in Egyptian. In the Hellenistic world, (related to Greek
culture from 323 B. C. to 31 B.C.), the art of alchemy
being intermingled with magic and occultism proliferated
first into the study of natural substances with the ultimate
goal of transmuting common cheap metals into attractive
gold or silver with ‘Philosopher’s Stone’ and inventing a
chemical concoction, ‘The Elixir of Life’, that would enable
people to live longer and cure all ailments. In alchemy,
known metals were considered in conjunction with heavenly
bodies.
The advent of alchemy was greatly influenced by the
Aristotle’s theory of four fundamental elements along with
two more alchemical elements, namely, sulfur, as ‘the stone
which burns’ symbolizing the properties of flammability
or combustion, and mercury, characterizing the properties
of volatility and stability, and in addition, salt indicated
the solidity. According to Swiss alchemist Paracelsus, the
four element theory of Aristotle appeared in bodies as three
fundamental metallic principles, the ‘tria prima’ of the
alchemists.
In medieval alchemy during 300 B. C. to 300 A.D.,
the Persian alchemist, Jabir bin Hayyan, as ‘the father of
chemistry’, led the foundations of a systematic scientific
approach towards the development of experimental
chemical research in the Arab World. Attempts were made
for classification of the alchemical processes and for
development of different experimental apparatus. In ancient
India, the chemical excellence in various aspects of
scientific developments was highly acclaimed and was far
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ahead of many of the existing civilizations during the
period. In ninth century, the inventions of laboratory
apparatus like alembic (apparatus for distilling), crucible,
retort, furnace; chemical analysis of substances; distinction
between acids and alkalis; manufacture of drugs; etc. were
achieved in chemistry.
Alchemy made extensive contribution to the evolution
of chemistry in Greco-Roman Egypt, India and the Arab
world and the Western alchemists, in general, became
influenced by the scientific experimental framework
developed in these regions, as the discipline migrated to
Renaissance Europe in twelfth century. In Europe,
Paracelsus (1493–1541) refuted the four element theory of
Aristotle and introduced a hybrid of alchemy and science
called as iatrochemistry. In 1556, Georg Agricola, known
as the ‘father of metallurgy’, through his presentation of
the processes for mining of metal ores and refining of
metals by smelting in ‘De re metallica’, tried to remove
the mysticism associated with the subject. Several chemists
contradicted the theories of alchemy and hinted for the
version of the conservation of mass suggesting that a
material body is capable of changing but can’t disappear.
A fraudulent side of alchemy was exposed, especially
in manufacturing of counterfeit gold from cheap substances,
in ‘Canon’s Yeoman’s Tale’ of Geoffrey Chaucer. In 1317,
the Avignon Pope John XXII ordered the alchemists to
leave France for the misdeeds. In England in 1403 the act
of ‘multiplication of metals’ was declared punishable by
death. In spite of such extreme measures, some group of
alchemists still sought to discover the ‘philosopher’s stone’
and ‘the elixir of life’, which, however, never happened
within the time period.
In alchemy, the alchemists although were not so
successful in elucidating the nature of matter or its
transformation, but have set the trend of modern chemistry.
Since the beginning of the fourteenth century, the alchemists
in general became more conscious about the reproducibility
of the scientific methods and experiments and felt the need
of specific vocabulary for systematic naming of the new
compounds and the invented terminologies. During the
period, along with popular exotic alchemy, the spiritual
alchemy was also flourished and realigned to its Platonic,
Hermetic and Gnostic roots and the symbolic quest for the
philosopher’s stone still continued to be the domain of
several respected scientists and intellectuals until the early
eighteenth century. Some of the early renowned modern
alchemists include Jan Baptist van Helmont, Robert Boyle
and Isaac Newton.
SCIENCE AND CULTURE, NOVEMBER-DECEMBER, 2016
Early Chemistry of 17th and 18th Centuries
Roger Francis Bacon in 1605 in his book, ‘The
Proficiency and Advancement of Learning’, presented an
outline of the scientific methods developed during the
period. Michal Sedziwoj in his alchemical treatise, ‘A New
Light of Alchemy’, in the same year, indicted the presence
of the ‘food of life’ in the air, later identified as oxygen.
Jean Beguin described the first-ever chemical equation in
his book, ‘Tyrocinium Chymicum’, in 1615. Rene Descartes
in 1637 presented a detailed description of the existing
scientific methods in his publication, ‘Discours de la
method’. A group of chemists, namely, Robert Boyle,
Robert Hooke and John Mayow, at Oxford being
encouraged by the new concept of the empirical
methods propounded by Bacon and others, began to reshape
the old alchemical traditions into an organized scientific
discipline of chemistry.
Robert Boyle (1627–1691) made a clear
differentiation between the activities of alchemy and the
scientific experimental approach towards matter initiating
the beginning of the history of modern chemistry. He
believed that the developed scientific methods denied the
limitation of chemical elements to only the four classical
elements of Aristotle and put forward a mechanistic
alternative of atoms and chemical reactions that could be
the subject of rigorous experiment. He suggested that all
theories must be experimentally proved before being
accepted as true. His work was involved with some of the
modern ideas of atoms, molecules and chemical reactions.
He favored the word corpuscle as finest division of matter
over atom. The book, ‘The Sceptical Chymist’, in which
he proposed the hypothesis that every phenomenon is the
result of collisions of particles in motion acted as a
landmark publication in the field of chemistry. He is
however best known for his Boyle’s Law introduced in
1662 describing the relationship between the pressure and
volume of a gas under different experimental conditions.
Robert Boyle for his pioneering contributions in chemical
science is regarded as the Founding Father of Modern
Chemistry.
During the period, it became evident that ‘air’ is
comprised of different gases. Jan Baptist van Helmont
coined the word ‘gas’ from the Greek word chaos in
naming some insubstantial substances present in the ‘air’
and is remembered today as the founder of pneumatic
chemistry. In 1754, Helmont along with Joseph Black
discovered carbon dioxide, called as ‘fixed air’. Helmont
in his work, Ortus medicinae, in 1648 proposed an early
version of the Law of conservation of mass. Black in 1758
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formulated the concept of latent heat to explain the thermochemistry of phase changes.
In 1702, German chemist Georg Stahl assigned the
name ‘phlogiston’ to the substance believed to be released
in the process of burning. J. J. Beecher proposed that in
the process of burning of a substance, phlogiston is added
to the flame of the burning object from air, in some cases,
producing a product. The English chemist Henry
Cavendish in 1766 discovered the colorless and odorless
gas, hydrogen, as ‘inflammable air’ which burns and can
form an explosive mixture with air. In 1774, the English
chemist Joseph Priestley isolated pure oxygen as
‘dephlogisticated air’, the existence of which was indicated
earlier in 1773 by the Swedish chemist Carl Wilhelm
Scheele as ‘fire air’. Cavendish suggested that oxygen is a
part of air that combines with substances as they burn.
Priestley is also credited for the discovery of soda water
and several other ‘airs’ (gases).
In eighteenth century, the French chemist AntoineLaurent de Lavoisier through his pioneering research and
development in chemistry established the subject on proper
theoretical footings. He proposed that air is composed of
two parts, namely, oxygen (Greek for acid-former) which
combines with metals to form calxes (powdery substance)
and the azote (Greek for no life). Lavoisier in his
‘Considérations Générales sur la Nature des Acides (1778)’
indicated that the ‘air’ responsible for combustion, was the
source of acidity and all acids contained oxygen. He also
demonstrated that the ‘inflammable air’ (hydrogen)
combined with the ‘dephlogisticated air’ (oxygen) to
produce a dew appeared to be water. Mikhail Lomonosov
in Russia anticipated the kinetic theory of gases during the
period.
Lavoisier with Pierre-Simon Laplace in 1782-83
introduced a technique for determination of the heat
involved in various chemical changes using an icecalorimeter leading to the foundation of thermo-chemistry.
In 1787, Lavoisier and Claude Louis Berthollet in their
‘Methods of Chemical Nomenclature’ described a new
system of chemical nomenclature for the chemical
compounds such as sulfuric acid, sulfates and sulfites still
in use today. Lavoisier in his publication, ‘Traite
Elementaire de Chimie (Elementary Treatise of Chemistry,
1789)’, which is considered as the first modern chemical
text book, presented a new theory as ‘Lavoisier’s Law’
elucidating the principle of conservation of mass. He
believed in the theory of radicals which functions as a
single group in a chemical reaction. He also indicated that
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diamond is a crystalline form of carbon. Lavoisier
introduced the use of chemical balance in the laboratory.
Lavoisier through his fundamental scientific
contributions towards systematic chemical experimentations
and their quantitative way of presentation brought about a
revolution in chemical science. He observed, “I have
tried...to arrive at the truth by linking up facts; to suppress
as much as possible the use of reasoning, which is often
an unreliable instrument which deceives us, in order to
follow as much as possible the torch of observation and
of experiment.” Lavoisier is celebrated as the ‘father of
modern chemistry’ and a chemical analogue of Isaac
Newton in physics.
During the period, the elements, cobalt, nickel and
tungsten, were respectively identified by the Swedish
chemist Georg Brandt in 1735, Axel Fredrik Cronstedt in
1751 and Lose and Fausto Elhuyar in 1783. Axel Fredrik
Cronstedt is considered as one of the founders of modern
mineralogy. Louis Claude Cadet de Gassicourt synthesized
the first organometallic compound, namely, cacodyl oxide in
1757. Berthelot in 1785 produced the strong chlorine
oxidant, potassium chlorate (KClO3), as Berthelot’s salt and
also determined the elemental composition of ammonia.
He also introduced the theory of chemical equilibrium.
The Italian physicist Alessandro Volta in 1784 while
investigating ‘animal electricity’ discovered by Luigi
Galvani utilizing frog leg as a detector devised an
electrochemical cell that derived electrical energy from
spontaneous redox reaction taking place within the cell.
Volta thus developed the electrochemical theory of chemical
combinations and became the founder of electrochemistry.
Michael Faraday through his studies on electro-deposition
of metals associated with quantities of chemical elements
during electrolysis, made a major contribution to
electrochemistry and provided important clues in elucidating
the atomic nature of matter.
Chemistry of 19th Century to the Present
In 1801-1802, the French chemist Joseph Louis GayLussac in his ‘Charles’s Law’ proposed that equal volumes
of all gases expand equally with the same increase in
temperature. Later in 1808, Gay-Lussac deduced ‘GayLussac’s Law’ or the ‘Law of Combining Volumes’
suggesting that gases at constant temperature and pressure
combine in simple numerical proportions by volume and
the resulting product or products bear a simple proportion
by volume to the volumes of the reactants. Gay-Lussac
along with Louis Jacques Thenard identified the element
boron through decomposition of boric acid.
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The English chemist John Dalton in 1803 described
the relationship between the components in a mixture of
gases and the relative pressure each contributes to that of
the overall mixture as Dalton’s law of partial pressures.
Dalton in his ‘New System of Chemical Philosophy (18081827)’ outlined the modern views on the atomic theory
and suggested that all matters are composed of small
indivisible ‘atoms’ and different atoms have different
atomic weights and also stressed that the chemical elements
combine in integral ratios which is known as ‘Dalton’s Law
of multiple proportions’. French chemist Joseph
Proust in1804 proposed the ‘Law of definite proportions’
which states that elements always combine in small and
whole number ratios to form compounds. The two laws,
the ‘Law of multiple proportions’ and the ‘Law of definite
proportions’, form the basis of the development of
stoichiometry, the term introduced by J. Benjamin Richter.
The English chemist Jons Jacob Berzelius in his
publication, ‘Lärbok i Kemien’, in 1808 introduced the
classical system of chemical symbols and notation. The
elements were abbreviated by one or two letters, for
example, O for oxygen, Fe for iron, etc. and the elemental
proportions in a compound were noted by numbers, the
same basic system used today. However, in presenting the
formula of a compound, Berzelius used a superscript
number, e.g., H2O, instead of the subscript used today, e.g.,
H 2 O. He also developed the theory of chemical
combination suggesting that reactions occur with stable
groups of atoms called radicals. His work on precise
determination of elementary constituents of large numbers
of compounds provided evidence in favor of Dalton’s
atomic theory that inorganic chemical compounds are
composed of atoms combined in whole number amounts.
Berzelius discovered the elements, silicon, selenium,
thorium and cerium, and the elements, lithium and
vanadium, were identified by his associates. He tried to
compile a table of the known elements on the basis of
their relative atomic weights in 1828. He believed that salts
are compounds of an acid and a base, and also indicated
that the anions in acids would be attracted to a positive
electrode (the anode) and the cations in bases to a negative
electrode (the cathode). He introduced the chemical terms,
catalysis, polymer, isomer and allotrope, although the
original definitions sometimes differ from modern usage.
Friedrich Wohler and the German chemist Justus von Liebig
in 1825 confirmed the concept of isomerism suggesting
that it is caused by differing in arrangements of the atoms
within a molecular structure. Berzelius for his original
contributions in science of chemistry is known as the father
of modern chemistry along with Lavoisier and Boyle.
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The English chemist Humphrey Davy, as one of the
pioneers in the field of electrolysis, discovered nine new
elements including the alkali metals, sodium and potassium,
and the alkaline earth metals, magnesium, strontium and
barium. In 1810, he renamed the ‘dephlogisticated marine
acid’, discovered earlier by Carl Wilhelm Scheele in 1774,
as the element, chlorine. Scheele also gave a hint for the
formation of aqua regia and identified nitrous oxide known
as laughing gas simply by inhaling. The French chemist
Bernard Courtois discovered the element iodine in 1811.
In 1815, Davy invented the Davy lamp, which allowed the
miners to work safely in the coal mines in presence of
flammable gases like methane but did not patent it for the
benefit of the workers.
The Italian physicist Amedeo Avogadro in his
‘Avogadro’s law’ in 1811 postulated that under control
conditions of temperature and pressure, equal volumes of
gases contain equal number of molecules. He also suggested
that simple gases are compound molecules of two or more
atoms and not of solitary atoms. In 1850s, several chemists
like Alexander Williamson in England, Charles Gerhardt
and Charles-Adolphe Wurtz in France and August Kekule in
Germany, advocated for reformation of theoretical
chemistry to make it consistent with Avogadro hypothesis.
Stanislao Cannizzaro constructed a systematic theoretical
structural concept that fit almost all of the available
empirical evidences and suggested that most of the
elementary gases are diatomic, some are monatomic and a
few are more complex. He also proposed a relation among
equivalent weight, atomic weight and molecular weight on
the basis of Avogadro’s hypothesis. Johann Josef
Loschmidt in 1865 predicted the exact number of molecules
in a mole, later named as Avogadro’s number.
The synthesis of the organic compounds, urea, by
Friedrich Wöhler in 1828 and acetic acid by Hermann
Kolbe in 1847 completely from inorganic sources, helped
in making an essential distinction between organic and
inorganic substances in chemistry. In 1827, William
Prout classified bio-molecules into their modern groupings
of carbohydrates, proteins and lipids. Wöhler and Justus
von Liebig explained functional groups and radicals in
relation to organic chemistry in 1832. By the end of the
century, hundreds of organic compounds like synthetic dyes,
drugs, etc. have been synthesized. Liebig, in addition to
his work in organic chemistry, also made major
contributions to agricultural and biological chemistry. The
German chemist Liebig for his contributions involving the
discovery of nitrogen as an essential plant nutrient and
formulation of the ‘Law of the Minimum’ dealing with the
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effect of individual nutrients on crops, is considered as the
‘father of fertilizer industry’.
Germain Hess in his law of conservation of energy,
known as ‘Hess’s law’, in 1840 established that the
energy change in a chemical process depends on the states
of the starting and product materials only and not on the
specific reaction pathway between the two states. In 1864,
Cato Maximilian Guldberg and Peter Waage proposed the
‘Law of mass action’. Louis Pasteur in 1849 suggested that
the racemic form of tartaric acid is a mixture of the
levorotatory and dextrorotatory forms, thus identifying the
nature of optical rotation which led to the initiation of the
field of stereochemistry. In 1873, Jacobus Henricus van’t
Hoff and Joseph Ahille Le Bel independently developed
the model for chemical bonding and studied optical
activity in chiral compounds. The concept of the
‘asymmetrical carbon atom’ provided an explanation for
the occurrence of numerous isomers.
William Thomson, better known as Lord Kelvin, in
1848 introduced the concept of absolute zero, the
temperature at which all molecular motion ceases. In 1852,
August Beer, on the basis of the work of Pierre Bouger
and Johann Heinrich, proposed the ‘Beer’s law’ which
explains the relationship between the composition of a
mixture and the amount of light it absorbs leading to the
development of the important analytical technique of
spectrophotometry. The technique of spectroscopy was
effectively utilized by Robert Bunsen and Gustav
Kirchhoff (1859-60) to discover the elements, caesium and
rubidium, and the British chemist Crookes to identify
thallium in some seleniferous deposits in 1861.
Benjamin Silliman Jr. in 1855 developed the methods
of petroleum cracking initiating research in the field of
modern petrochemical industry. The refinement of
petroleum extracted from earth provided a host of liquid
fuels such as gasoline, diesel, solvents, lubricants, waxes
and many other common materials of the modern world,
such as synthetic fibers, plastics, paints, detergents,
pharmaceuticals, adhesives and ammonia as fertilizer. The
preparation of the dye, mauveine or Perkin’s mauve, by
Sir William Henry Perkin in 1856 and that of indigo dye
by Adolf von Baeyer from coal tar in 1865, formed the
milestone for the synthesis of dyes in industrial organic
chemistry. Similarly, in 1862, Alexander Parks synthesized
a new synthetic polymer, Parkesine, leading to the
foundation of the modern plastics industry. One of the first
commercially available plastics, Bakelite, was invented by
Leo Baekeland during the period.
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The German chemist August Kekule von Stradonitz
in his book, Lehrbuch der organischen Chemie (Textbook
of Organic Chemistry), in 1859 indicated that tetravalent
carbon atoms can link together to form a ‘carbon chain’ or
a ‘carbon skeleton’, to which other atoms like hydrogen,
oxygen, nitrogen and chlorine can be attached. In 1865,
Kekulé established the cyclic structure of benzene as a six
carbon ring with alternate single and double bonds and
described the nature of the aromatic compounds based on
benzene molecule. The Swedish chemist Alfred Nobel
prepared an explosive compound, nitroglycerin,
incorporated in a safer inert absorbent like kieselguhr
(diatomaceous earth) and patented as dynamite in 1867.
Nobel later developed a more powerful explosive than
dynamite, a transparent jelly-like substance, Gelignite or
blasting gelatin, in 1876.
In nineteenth century, several scientists in facilitating
their studies in science felt the need to classify and
systematically arrange the elements already discovered
during the period. In 1815, William Prout was the first to
propose for arrangement of the elements in order of their
atomic weights as the atomic weights of the known
elements were found to be the exact multiples of the atomic
weight of hydrogen. Johann Wolfgang Dobereiner in 1817
tried to draw a relation between the atomic weights and
the properties of the elements through his concept of ‘triad’.
Berzelius in 1828 compiled a table of relative atomic
weights of 43 known elements setting the weight of oxygen
exactly equal to 100. In 1862, Beguyer de Chancourtois
tried to arrange the elements in the order of their ascending
atomic weights in a telluric helix form, a three-dimensional
version of the periodic table. John A. R. Newlands in 196365 devised the ‘law of octaves’ which was further modified
by Luther Myer of Germany to organize the elements in a
periodic table in 1864.
The Russian chemist Dmitri Mendeleev made a
breakthrough in devising a systematic periodic classification
of the 66 known chemical elements in the ascending order
of their atomic weights in the modern form of the Periodic
Table. The periodic table published in his Principles of
Chemistry in 1869, displayed a recurring pattern or
periodicity of properties within groups of the known
elements. In the later version of his periodic table published
in 1871, he confidently predicted the positions and the
likely properties of three yet-to-be-discovered elements,
designated as eka-boron (Eb), eka-aluminum (Ea) and ekasilicon (Es). The predictions for the yet-to-be discovered
elements were proved to be the properties of the elements,
scandium, gallium and germanium, respectively discovered
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later and each of which filled the assigned position in the
periodic table.
In 1894, Scottish chemist William Ramsay and Lord
Rayleigh discovered the monatomic and chemically inert
gaseous element argon in air. In the following year, Ramsay
identified another inert gaseous element from cleveite
mineral and named it as helium, the presence of which
was indicated earlier in the solar spectrum. Ramsay and
the British chemist Morris W. Travers in 1898 isolated three
more inert gaseous elements, neon, krypton and xenon,
from air. The discovery of the inert gases, later called as
noble gases, resulted in completion of the basic structure
of the periodic table. In designing the periodic table, the
great visionary, Dmitri Mendeleev, as an icon in science
embodied the most fundamental principles lying at the core
of the subject of chemistry.
Antonius Van den Broek in 1911 suggested that the
elements would be more properly organized in the periodic
table if the elements were arranged on the basis of their
positive nuclear charges rather than that of their atomic
weights. In 1913, Henry Moseley following the work of
Broek introduced the concept of atomic number and
proposed that the properties of the elements are periodic
functions of their atomic numbers and not atomic weights
as indicated by Mendeleev and others. Presently, to
identify the periodic trends, the chemical elements are
arranged in groups or columns and periods or rows
primarily based on the increasing orders of their atomic
numbers in the periodic table. With wide acceptance, the
periodic law and the table have now become the basic
framework for a great part of chemical science.
American physicist J. Willard Gibbs in his study on
thermodynamic, introduced the concept of chemical
potential or the ‘fuel’ that makes chemical reactions to take
place. In Gibbs’ phase rule, he included almost all the
variables like temperature, pressure, energy, volume and
entropy generally involved in a chemical reaction. In
1884, van’t Hoff proposed a general thermo-dynamical
relationship between the heat of conversion and the
displacement of equilibrium as a result of temperature
variation in chemical kinetics. The concept of this mobile
equilibrium was subsequently modified by Henry Louis Le
Chatelier in 1885 through the ‘van’t Hoff-Le Chatelier
principle’ or simply ‘Le Chatelier’s principle’. The
application of thermodynamics to chemistry by Gibbs and
others was instrumental in transforming physical
chemistry into an important branch of deductive science in
chemistry.
SCIENCE AND CULTURE, NOVEMBER-DECEMBER, 2016
Hermann Emil Fischer (1884-86) studied the
chemistry of glucose and related sugar and also synthesized
and proposed the structure of purine, a key structure in
different bio-molecules. Alfred Werner through his work
on the octahedral structure of cobalt complexes established
the field of co-ordination chemistry in 1893.
In the last decade of the nineteenth century, several
landmark discoveries on the sub-atomic particles and the
atomic structure encouraged the scientists in initiating a
new field of research in Nuclear Science. J. J. Thomson in
1897 discovered the negatively charged particle, electron,
the first particle to be recognized as a constituent of all
atoms using the cathode ray tube. Eugene Goldstein in 1886
and Wilhelm Wien in 1898 predicted the existence of the
positively charged particle as canal rays or positive rays
(streams of positive ions) with a charge equal and opposite
to the negatively charged electron and Rutherford in 1920
suggested the name, proton, for this positively charged
particle. The electrically neutral nuclear particle, neutron,
was however, discovered later by James Chadwick in 1932.
Studies on canal rays by Wien in 1898 led to
the development of the important analytical technique of
mass spectrometry.
During the period, Wilhelm Conrad Roentgen while
working on the effect of cathode rays on barium
platinocyanide, discovered X-rays in 1895. Similarly, in
1896, Henri Becquerel in his studies on fluorescence with
potassium uranyl sulfate observed that the salt emits a
fluorescent light with or without the aid of sunlight and he
termed it as ‘Becquerel Rays’ or ‘Uranic Rays”. Thus, the
phenomenon of radioactivity was discovered and the term
‘radioactivity’ was first used by Polish-born Marie
Sk³odowska Curie. Marie Curie along with her husband,
French physicist Pierre Curie in 1898 discovered two new
radioactive elements, radium and polonium, in pitchblende
mineral through their nuclear properties of radioactivity.
Earnest Rutherford in 1906 developed an atomic
model, known as ‘Rutherford model’, which was later
modified by Danish physicist Niels Bohr and Henry
Moseley. In 1911, Rutherford while studying the
characteristic properties of radioactivity, discovered three
types of radiations, namely, alpha particles (α, positively
charged), beta particles (β, negatively charged) and gamma
rays (γ, neutral electromagnetic radiation) and also
demonstrated that atoms of one radioactive element would
spontaneously turn into atoms of another element with
emission of radiation. Bohr in 1913 introduced the concept
of quantum mechanics to atomic structure through his ‘Bohr
model’. He also postulated that electromagnetic radiation
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is absorbed or emitted when an electron moves from one
orbit to another producing a characteristic emission
spectrum for the element. Frederick Soddy introduced the
concept of isotopes in 1913 and also discovered the element
protactinium in 1917.
Rutherford in 1919 reported the discovery of
artificially induced nuclear transmutation, the dream of the
earlier alchemists, through a nuclear reaction between
nitrogen atoms and alpha particles producing oxygen atoms
and protons, represented as 14N(α, p)17O. During the period,
different advanced nuclear devices like the cyclotron
conceived by E. O, Lawrence in 1929 and the electrostatic
accelerator built by Cockcroft and Walton in 1932 for
accelerating nuclear particles as projectiles to cause nuclear
transmutation were invented. Irene Curie-Joliot and her
husband Frederic Joliot in 1934 demonstrated that
radioactive elements could be created artificially in the
laboratory. The German scientist Otto Hahn along with his
coworkers in 1939 discovered the neutron induced nuclear
fission resulting in release of a large amount of nuclear
energy. In USA, the Manhattan Project was in process at
the University of Chicago and the very first nuclear fission
reactor was developed under the leadership of Enrico Fermi
in 1940. The important discoveries and outstanding
achievements in nuclear science since the last decade of
the nineteenth century, in general, resulted in the
development of a new branch of chemistry in chemical
science, namely, nuclear chemistry.
In the beginning of the twentieth century, the
American scientists Linus Pauling and Gilbert N Lewis
established the electronic theory of chemical bonds and
molecular orbital, known as ‘valence bond theory’. In 1902,
Lewis suggested that the chemical bonds are formed
through the transference of electrons in the outermost
‘valence’ shell of the atom, to give each atom a complete
set of eight outer electrons (an ‘octet’). In the article ‘The
Atom of the Molecule’ in 1916, he indicated that a chemical
bond is formed by a pair of electrons shared by two atoms
and also introduced the ‘electron dot diagrams’ to symbolize
the electronic structures of atoms and molecules, now
known as ‘Lewis structures’. Subsequently, American
chemist Irving Langmuir in1919 introduced the term
covalent bond. In 1920s, the Lewis’s model of the electronpair bond was effectively applied by the British chemists
Arthur Lapworth, Robert Robinson, Thomas Lowry and
Christopher Ingold in organic chemistry and the American
chemist Maurice Huggins and the British chemist Nevil
Sidgwick in coordination chemistry. In 1912, Peter
Debye developed the concept of molecular dipole to
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describe asymmetric charge distribution in some molecules.
In 1923, Lewis and M. Randall published ‘Thermodynamics
and the Free Energy of Chemical Substances’, the first
modern treatise on chemical thermodynamics.
Lewis developed the electron pair theory of acids and
bases in which an acid as any atom or molecule with an
incomplete octet is capable of accepting electrons from
another atom and a base is, of course, an electron donor.
In 1909, S. P. L. Sorensen developed the concept of pH in
measuring acidity. Svante Arrhenius in his acid-base theory
stated that an acid is a substance that produces hydronium
ion when it is dissolved in water and a base is one that
produces hydroxide ion in water. Acidity based on
Brønsted–Lowry definition was expressed as the acid
dissociation constant (Ka) which measures the relative
ability of a substance to act as an acid.
The important analytical technique, chromatography,
was invented by Mikhail Tsvet in 1903. The development
of the Haber or Haber-Bosch process by Fritz Haber and
Carl Bosch in 1905 for preparation of ammonia through
combination of nitrogen and hydrogen has become an
important landmark in industrial chemistry with deep
consequences in agricultural production of fertilizers and
munitions. Haber has been considered as the ‘father of
chemical warfare’ for his work on deploying chlorine and
other poisonous gases during World War I. In 1912,
William Henry Bragg and William Lawrence
Bragg proposed ‘Bragg’s law’ and developed the technique
of X-ray crystallography, effectively utilized as a tool in
elucidating the crystal structure of substances.
In 1924, the French quantum physicist Louis de
Broglie introduced the theory of electron waves based on
‘wave-particle duality’ in which he proposed that particles
can behave like waves and waves (radiation) can behave
like particles. In 1926, Austrian physicist Erwin
Schrödinger on the basis of the wave-particle duality theory
introduced a wave equation, known as the Schrodinger
equation. Austrian-born physicist Wolfgang Pauli in 1925
through his ‘Pauli Exclusion Principle’ which states that
no two electrons around a single nucleus in an atom can
occupy the same quantum state simultaneously, made major
contributions to the development of the quantum mechanics
and quantum field theory. German physicist Werner
Heisenberg in formulating quantum mechanics in terms of
matrices introduced his ‘uncertainty principle’ regarding the
status of an electron in an atom in 1927. Studies on the
application of quantum mechanics to the diatomic
hydrogen molecule and the phenomenon of the chemical
bond by Walter Heitler and Fritz London in 1927 are often
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considered as the milestones in the history of quantum
chemistry.
In 1953, the heuristic approach of James Watson and
Francis Crick in deducing the double helical structure of
DNA capable of explaining by the knowledge of chemistry
and the X-ray diffraction patterns, led to an explosion of
research in the field of biochemistry. The development of
the method of polymerase chain reaction (PCR) by Kary
Mullis in 1983 for in-vitro amplification of DNA in the
laboratory has made possible the study of sequence of DNA
of organisms culminating in the growth of the human
genome project. Miller-Urey demonstrated that the basic
constituents of proteins and amino acids could themselves
be built up from simpler molecules in a simulation of
primordial processes on earth and this was perhaps the first
attempt by chemists to study hypothetical processes of the
origin of life in the laboratory under controlled conditions.
Harold Kroto, Robert Curl and Richard Smalley in
1985 discovered fullerenes, a class of large carbon
molecules, superficially resembling the geodesic dome. The
carbon nanotube, a cylindrical type of fullerene, invented
through electron microscopy by Sumio Lijima in 1991, is
being used as an important component in the field of
nanotechnology. In 1970, John Pople developed the
Gaussian program suitably applied to computational
chemistry. Eric Cornell and Carl Wieman in 1995 produced
the first Bose-Einstein condensate, a substance that displays
quantum mechanical properties on the macroscopic scale.
In mid-twentieth century, chemical investigations on
the quality and purity of the intrinsic semiconductor
materials like single crystals of silicon and germanium and
their chemical compositions when doped with other
elements, made possible the production of the solid state
transistors and other precise electronic devices, especially
computers in the later stage of its scientific advancements.
Since 1950s, several important discoveries in nuclear
science have resulted in the synthesis of the heavy and
super-heavy elements beyond uranium with sufficient
stability enabling to study their properties in conformity
with periodic law of the periodic table. American nuclear
chemist G. T. Seaborg along with others is best known for
the discovery and isolation of the trans-uranium elements.
The chemical element, Seaborgium (element 106), was
named in his honor during his life time like that of the
chemical element, Einsteinium (element 99), named to
honor Albert Einstein. Currently, several groups of nuclear
scientists have been engaged in successful synthesis of the
super-heavy elements in different advanced nuclear research
laboratories in USA, USSR, France and Germany and the
SCIENCE AND CULTURE, NOVEMBER-DECEMBER, 2016
latest evidence of their endeavor is the production and
characterization of the super-heavy element, Z-117, through
the nuclear reaction, 249Bk(48Ca, 3-4n)293,294Z-117, in GSI,
Germany, also reported earlier by a Group of Russian
scientists in 2010.
In the earlier period, the chemists in general were
very much reluctant in the application of mathematics in
chemistry. Auguste Comte in 1830 made the comment,
“Every attempt to employ mathematical methods in the
study of chemical questions must be considered profoundly
irrational and contrary to the spirit of chemistry”. However,
in the later part of the nineteenth century, the conception
has gradually been changed, for example, August
Kekule wrote “I rather expect that we shall someday find
a mathematico-mechanical explanation for what we now
call atoms which will render an account of their
properties’’. With rapid progress and outstanding
development in chemical research, the activities of
chemistry have now become intermingled with almost all
major branches of science resulting in extensive
advancement of science in general.
Disciplines of Chemistry
In practice, the subject of chemistry is now
traditionally grouped into several major sub-disciplines
based on the type or kind of matter being investigated,
although there are several cross-disciplinary and more
specialized fields in chemical science. Some of the major
sub-disciplines of chemistry are – Analytical chemistry
(deals with chemical composition and structure of sample
materials), Biochemistry (deals with substances of biological
organisms), Inorganic chemistry (deals with inorganic
matters), Nuclear chemistry (deals with sub-atomic nuclear
particles and transmutations), Organic chemistry (deals with
carbon based matters), Physical chemistry (deals with the
chemical processes involving physical concepts such as
thermodynamics, quantum mechanics, etc.) and others.
In addition, many more specialized fields such as
Agro-chemistry, Atmospheric chemistry, Chemical biology,
Cosmo-chemistry, Electrochemistry, Environmental
chemistry, Geo-chemistry, Green chemistry, Marine
chemistry, Material science, Nanotechnology, Natural
product chemistry, Petro-chemistry, Pharmacology, Photochemistry, Polymer chemistry and many others, have been
emerged in recent years with rapid advancement in
chemical sciences.
Conclusion
Studies in chemistry, in early civilizations, were
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primarily confined to simple observations on the natural
materials under the environmental conditions of
temperature, pressure and exposition to natural solar
radiations on Earth. Gradually, the rational reasoning on
the existences of the surrounding matters in different phases
started with the acceptance of the fundamental concepts
and laws time to time introduced in the development of
modern chemistry. In the beginning, however, the matters
within the atomic nuclei or the nuclear phenomenon were
disregarded. With the advancement of science, the subject
of chemistry has been re-defined as the science of matter
dealing with the composition and structural properties of
substances and their transformations under different
conditions, both natural and artificial.
Discovery of radioactivity, the sub-atomic particles
and studies on the atomic structure in the later period of
modern chemistry encouraged the scientists to rethink about
the characteristic properties of matter. Studies on matters
in their atomic, molecular or aggregate scale, including the
effects of interactions (bombardment) of fundamental
particles like proton, neutron or heavy ions with matter
are now formally recognized as essential subjects of
investigation in chemistry. Presently, the advanced areas
of chemical science like quantum chemistry, nuclear
chemistry and many others have been extensively developed
and formally accepted as important sub-fields of study in
chemistry. Nevertheless, the field of chemistry is very broad
and is sometimes considered as the central science as it
bridges many other major branches of science and hence
the claim that chemistry is everywhere is found to be true
and justified.
Appendix
Scientists engaged in studies in chemical science are
generally designated as chemists and the subject involved
is known as chemistry. Some essential concepts of study
in chemistry are atom, element, molecule, compound, ion,
bonding, energy, etc. Matter can exist in several phases
and can be studied in isolation or in combination. The most
familiar phases are solid, liquid and gaseous and the less
familiar phases include plasmas, Bose-Einstein condensates
and fermionic condensates, and paramagnetic and
ferromagnetic phases of magnetic materials.
According to the International Union of Pure and
Applied Chemistry (IUPAC) gold book, a chemical reaction
is ‘a process that results in the inter-conversion of chemical
species’. A chemical reaction can be depicted symbolically
through chemical equation. The number of atoms on the
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left and the right sides of a chemical reaction for chemical
transformation is equal but when unequal, the
transformation by definition is not chemical, but rather a
nuclear reaction or a radioactive decay process. The
standard nomenclature of a chemical compound is set by
the IUPAC. The Chemical Abstracts Service has devised a
method to index chemical substances. In the initiative of
the IUPAC and of the United Nations Educational,
Scientific, and Cultural Organization (UNESCO), the year
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2011 was declared by the United Nations as the
International Year of Chemistry.
The present article is primarily based on the (i)
History of Chemistry, Wikipedia, the free encyclopedia and
(ii) Chemistry, Wikipedia, the free encyclopedia, retrieved
on 23. 09. 2015. To have detailed information, further
readings of the cited Wikipedia along with the referred
references and other relevant communications are
needed.
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