What is Chemistry: Definition, Branch, History

Chemistry is a branch or part of physical science which deals with the study of properties of matter. By matter, we mean substances we can see, feel, touch, taste, and smell.

Chemistry is concerned with the physical and chemical properties of the matter, its chemical composition (i.e. structure), the physical and chemical changes it undergoes and the energy changes that associated with these substances.

In this universe, all objects are made up of matter. Most of these objects are visible in the form of solids and liquids, but some exist in invisible forms such as gases.

Chemistry is a material science that concern with all material substances such as water, air, rocks, minerals, plants, animals, human, and the earth on which we all live, and other planets. So, we can say that chemistry is the study of all about matter or stuff in the world.

Definition of Chemistry by Famous Scientist

A famous scientist of the twentieth century, Linus Pauling defined the chemistry. He said that

Linus Pauling was one of the greatest chemists of the 20th century and won a two-time Nobel Prize. He defined chemistry as the study of materials, their internal structures, and how they transform during reactions.

Importance of Chemistry in Our Daily Life

Chemistry is a very interesting and fun subject. In our daily life, it touches almost every aspect of our lives, culture, and environment. It has changed our civilization and culture to a great extent. In the present day, chemistry has provided more comforts to making a human’s life healthier and happier.

It provides major contributions to agricultural, biochemistry, environmental science, medicinal chemistry, metallurgy, and many other fields. These days we are using numerous materials that were unknown at the turn of the century.

A few decades back, our clothes and footwears were exclusively made up of natural origin, such as vegetable fibers, wool, hair, and skin of animals. Now the synthetic fibers made in chemical factories have largely replaced them.

Modern chemistry has provided human several new things, such as metal alloys, fertilizers, plastics, fuels, building materials, energy sources, drugs, etc.

Examples of Modern Chemistry

From the time we get up in the morning until we go to bed at night, chemistry touches every part of our lives. What we eat, what we wear, how we get around, and even the cool electronic devices we cannot live without – chemistry has contributed in some way to the making of each of these things.

Below are several key areas where chemistry plays an important role in our daily life.

1. Clothing

• Many of the fibers that compose the materials for our clothes are naturally occurring. Silk and cotton are examples of natural fibers.
• Silk is produced by the silkworm, and cotton is grown as a plant. However, several chemical processes are used to treat silk thread so that it is shrink-resistant and will repel water.
• Chemical dyes are frequently used to color various fabrics.
• Cleaning requires special soaps or chemicals used to dry-clean materials.
• Cotton will grow better if the boll weevil (an insect that kills the plant) is eliminated with the use of specific insecticides.
• Ironing of cotton is made easier by the use of chemicals that produce a permanent press in the material.
• Nylon, orlon, polyester, and several other polymers are man-made fabrics. Many of these materials are made from hydrocarbons found in petroleum products.
• Synthetic polymers are also used in shoes, rainwear, and camping items.
• Synthetic fabrics tend to be lighter than natural ones and can be treated to make them water-resistant and more durable.

2. Transportation

• Earlier, car bodies were made of sheet metal, which could be repaired by hammering after collisions.
• Modern vehicles use plastic parts, which are:
  • Easier to manufacture,
  • Lighter in weight, and
  • More fuel-efficient.
• Many of the engine components are now made of special metal alloys to increase the lifetime of the engine and to make it more efficient.
• Gasoline and oils are complex chemical mixtures formulated to:
  • Burn efficiently,
  • Produce energy effectively, and
  • Reduce air pollution.
• The refining of gasoline is a sophisticated chemical process that improves engine performance.

3. Farming and Gardening

• The most important requirements for crop growth are water, nutrient-rich soil, and protection from predators such as insects. Chemistry has played a major role in all three of these areas.
• Water purification uses chemical and physical processes to remove salt and harmful contaminants that could pollute the soil.
• Through chemical analysis of soil, farmers can see what nutrients the soil is lacking so these nutrients can be added.
• Fertilizers and weed killers enrich soil and protect plants from nutrient competition.
• Pesticides and insecticides prevent insects from damaging crops.
• These agricultural chemicals help increase crop yield and food quality.

4. Health Care

Chemistry plays a vital role in medicine and health:

• New drugs are developed through chemical analysis and the synthesis of new compounds.
• Practically all the drugs that you might see advertised on television are designed and created by chemists.
• Clinical laboratory tests for high cholesterol, or diabetes use a wide variety of analytical chemical techniques and instruments.
• Chemistry also plays a major role in the preparation and use of surgical materials such as stitches, artificial skin, and sterile materials.
• Laboratory tests that at one time were only available in hospitals can now be found in your local drug store because of developments in chemistry. For example, you can test your blood glucose using a simple portable device that runs a chemical test on a blood sample.
• Chemistry is also used to produce insulin and the disposable syringes used to administer the drug.

From the above points, it is clear that chemistry influences nearly every aspect of modern life — from the clothes we wear and the food we grow to the vehicles we drive and the medicines we use. It is truly the science of everyday living.

Branches of Chemistry

During the last few decades, the enlargement of chemistry has been enormous. The extent of chemistry has become wide and complex. Chemistry has traditionally classified into various branches for convenience and a better understanding of the subject.

The five main branches of chemistry are as follows:

• Organic chemistry
• Inorganic chemistry
• Physical chemistry
• Analytical chemistry
• Biochemistry

Some of the specialized branches of chemistry are:

• Medicinal chemistry
• Soil and agriculture chemistry
• Geochemistry
• Industrial chemistry
• Nuclear chemistry
• Structural chemistry
• Polymer chemistry
• Limnochemistry
• Phytochemistry

Let’s discuss in brief about each branch of chemistry.

Organic Chemistry

Organic chemistry is basically concerned with the study of compounds of carbon except carbonates, bicarbonates, cyanides, isocyanides, oxides of carbon, and carbides.

The main focus of organic chemistry is on the study of hydrocarbons (carbon and hydrogen) and their derivatives. Organic chemistry is important for our life studies and all life-related chemical reactions.

Scientists have discovered approximately 7 million different organic compounds present, while there are only 1.5 million known inorganic compounds. This large number of organic compounds originates from the unique property of carbon.

Inorganic Chemistry

This branch of chemistry actually deals with the study of all known elements and their compounds except organic compounds. It is concerned with the substances gained from minerals, air, sea, and soil.

Physical Chemistry

This branch of chemistry mainly deals with the physical properties and constitution of matter, the laws of chemical combination and theories governing reactions. In physical chemistry, we understand the effect of temperature, pressure, light, concentration, etc., on reactions.

Analytical Chemistry

This branch is concerned with various methods of analysis of chemical substances, both qualitative and quantitative. It involves both chemical and physical methods of analysis.

Biochemistry

Biochemistry branch mainly deals with the studies of the substances related to living organisms and life processes.

Other Specialized Branch of Chemistry

Apart from the main branches like organic, inorganic, physical, analytical, and biochemistry, there are several specialized branches of chemistry that focus on specific areas of study. These branches explore unique aspects of matter, reactions, and applications in industries, research, and everyday life. They are explained below in brief.

Medicinal Chemistry

This branch is concerned with the application of chemical substances for the prevention and cure of various diseases in living beings.

Soil and Agriculture Chemistry

This branch of chemistry is concerned with the analysis and treatment of soils to increase its fertility for the better yields of crops. It mainly deals with the chemicals used as fertilizers, insecticides, germicides, herbicides, etc.

Geochemistry

This branch is concerned with the study of natural substances like ores and minerals, coal, petroleum, etc.

Industrial Chemistry

This branch includes the study of chemical processes for the production of useful chemicals on a large scale at relatively low costs.

Nuclear Chemistry

This is the most recent branch that deal with the study of nuclear reactions, the creation of radioactive isotopes and their applications in several fields.

Structural Chemistry

This specialized branch is concerned with various techniques used to clarify the structure of chemical substances. It mainly studies the properties of substances in terms of their structure.

Polymer Chemistry

This specialized branch concerned with the study of chemical substances of very high molecular masses of the order of 100,000 or higher, known as natural or artificial polymers. It is gaining a lot of popularity as the use of rubber, plastics, synthetic fibers, silicones, etc., is on the increase these days.

Limnchemistry

This specialized branch is concerned with the study of chemistry involved in the river water or water reservoirs.

Phytochemistry

This subbranch deals with the study of chemistry of plants.

Thus, we can say that there is no other branch of science that has so wide scope as chemistry.

Brief History of Chemistry

It is difficult to tell the exact date when the science of chemistry came into existence. However, its growth must have gone side by side with the development of civilization. Broadly, we can divide the history of chemistry under five periods of its development. They are as:

• Ancient period up to 350 A.D.
• Alchemical period (350-1500)
• Latrochemistry period (1500 – 1650)
• Phlogiston period (1650 – 1774)
• Modern period (1743 – 1793)

(i) Ancient Period up to 350 A.D.:

In ancient times, people had known many chemical operations such as souring of milk, conversion of sweet juices into wines, the conversion of wines into vinegar, etc.

Around 3000 BC, many countries like India, China, Egypt and Greece had known about techniques of making glass, pottery, pigments, dyes, perfumes and extraction of metals, especially gold and silver.

Around 400 BC, the beginning of chemistry as a branch of science could probably set when the theory was proposed that everything is made up of four elements: earth, air, fire and water.

Alexandrian wrote the first book of chemistry in Egypt around 300 A.D. The word chemistry meant the Egyptian art.

(ii) Alchemical Period (350-1500):

During this span, scientists (called alchemists) well tried to discover two things: an elixir of life which could make man forever young and a philosopher’s stone which could transform base metals like copper, iron, zinc, etc., into gold. But alchemists failed in their attempts because no elixir of life and philosopher’s stone actually existed on the earth.

However, we are indebted to them for designing new types of equipment. They discovered new chemical operations such as distillation, sublimation, extraction of gold by the amalgamation process and preparation of caustic alkalies from ashes of plants.

What is the philosopher’s stone?

The philosopher’s stone (believed by medieval alchemists) is the name of a substance that had the power to transform base metals into gold or silver. According to some, it had the power of prolonging life and of curing all injuries and diseases. The pursuit of this magical philosopher’s stone by alchemists led to the discovery of various chemical substances. However, the philosopher’s stone has later on proved fictional.

(iii) Latrochemistry Period (1500 – 1650):

During this era, chemists given their attention towards medico-chemical problems. They believed that the primary aim of chemistry was to develop medicines and not to make gold from base metals.

During this period, scientists started the study of gases and they undertook quantitative experiments for the first time. A modern chemist named Robert Boyle (1627-1691) found that when a metal is heated in air, its mass increases. He also constituted the relationship between volume and pressure of a gas.

(iv) Phlogiston Period (1650-1774):

A german chemist and physicist Georg Ernst Stahl proposed the phlogiston theory in the early 1700s. In this theory, he held that the materials, such as coal, or wood are burned, they given off combustible material substance called “phlogiston”. Phlogiston is the name of substance given off during the process of combustion.

This theory hang on for approximately 100 years and was a center of much controversy. During the end of the eighteenth century, scientists, especially by Joseph Black, Henry Cavendish, Joseph Priestley, and Carl Scheele, had done much work with gases. Priestley was a very conservative scientist that he still believed in phlogiston theory even after his discovery of oxygen.

(v) Modern Period:

The history of chemistry in its modern period is often considered, having begun with British scientist Robert Boyle (1627 – 1691). We know him for the best of his discovery of Boyle’s law (volume of gas is inversely proportional to its pressure at constant temperature). He was a pioneer in using scientific methods and experiments. He also worked to remove the mystique of alchemists from chemistry to make it a pure science.

A French chemist Antoine Laurent de Lavoisier (1743-1793) is regarded as “the father of modern chemistry“. He described the exact explanation of combustion by suggesting that oxygen is an essential component for combustion. This concept was responsible for great extent in overthrowing of the phlogiston theory.

Among his other contributions, he established the modern terminology for chemical substances and performed the first experiment in quantitative organic analysis. In 1789, He discovered or established the law of conservation of mass in chemical reaction.

During the first decade of the nineteenth century, John Dalton, a British chemist who proposed the basic theory of modern chemistry. He proposed his first theory in 1803, states that each element is made up of its own kind of atoms and atoms of different elements differ in their masses. He also determined the relative masses of atoms of various elements.

In the history of modern chemistry, Swedish chemist Jons Jakob Berzelius (1779 – 1848) had also given the individually important role. He devised the modern chemical symbols, determined atomic weights, contributed to the atomic theory, and invented several new elements.

He explained the preparation, purification, and analysis of two thousand chemical compounds and then determined atomic weights for forty elements. Berzelius also simplified the chemical symbol by introducing a notation – letters with numbers that completely replaced the pictorial symbols and that we are still using today.

Laws Discovered by Famous Chemists

A new era had risen. The other most famous and important chemists of this period that discovered many laws are as follows:

• Richter – Law of reciprocal proportions (1794)
• Proust – Law of definite proportions (1799)
• Gay-Lussac – Law of combining volumes of gases (1808)
• Avogadro – Avogadro hypothesis (1811)
• Faraday – Laws of electrolysis (1833)
• Thomas Graham – Law of gaseous diffusion (1861)
• Mendeleev – Periodic law and periodic table (1869)
• Arrhenius – Theory of ionization (1887)
• Henri Becquerel – Discovery of radioactivity (1896)
• Madam Curie – Discovered radium and polonium (1898)

The twentieth century is considered as an active time of modern chemistry. During this era, modern chemistry has made various contributions to human knowledge and civilization.

Now, we are living in a world of synthetic materials. Modern chemistry of today is actually helping us in solving major problems of our present day civilization such as food and diseases, depletion of sources of energy, depletion of natural sources, population explosion, and environmental pollution.

FAQs on Chemistry