What is chemistry

It is the branch of science that deals with the study of structure, composition, reactions, properties and applications or uses of matter. It mainly focuses on the atom, ions, molecules and the elements and compounds formed by them. Besides this, the interaction between matter and energy is also studied in chemistry. The father of chemistry is Lavoisier. The basic definition of chemistry is the study of matter and its properties.

Chemistry is a part of our daily life. Chemical reactions are happening continuously around us and in our body. The food we eat goes through chemical reactions to produce energy, movement of muscles while walking, running, etc., also involve chemical reactions. Let us see some of the examples in our daily lives that involve chemistry, such as;

• Photosynthesis: It a process by which plants produce their food. It is a chemical reaction in which water and carbon dioxide in the presence of sunlight react to form glucose and oxygen.
• Soaps and detergents: They are produced by using a chemical process called saponification and they remove dirt through a chemical process called emulsification.
• Sunscreen: The sunscreens and lotions that we apply to our body as protection from harmful UV rays are also based on chemistry.

Chemistry is divided into five main branches that include organic chemistry, inorganic chemistry, physical chemistry, analytical chemistry and biochemistry.

1) Organic chemistry

This branch deals with the study of organic compounds; the compounds made of carbon and hydrogen or in which carbon atoms are bonded with hydrogen such as carbonic compounds. It mainly focuses on the structure and chemical composition of organic compounds including their physical and chemical properties and the chemical reactions, which they undergo.

The research and development in organic chemistry have made lots of contributions to human life such as production of the drugs, vaccines, polymers and other useful products. Besides this, synthetic organic chemistry, an important part of organic chemistry, deals with the construction of particular chemical compounds from simple compounds for practical purposes.

Organic chemistry is very diverse due to the special property of the carbon element, which is known as carbon catenation. It allows an element to form bonds with the same type of atoms. This property of carbon allows it to form stable bonds with other carbon atoms and thus to form complex and stable molecules. The father of organic chemistry is Friedrich Wohler.

Applications of organic chemistry:

• Fuels like petrol, gasoline, natural gas, and charcoal, wood are organic compounds.
• The fabrics which are used to make clothes, such as nylon, rayon and polyester, is also made of organic compounds.
• The production of soaps, perfumes, shampoos, nail polish remover, dyes, candles also involves organic chemistry.
• The polymers like polyethylene, cellulose, PVC, nylon are organic molecules.
• The production of cosmetic products to address skin problems and improve beauty also make use of organic chemistry.

So, most of the products that we use involve organic chemistry such as furniture, vehicle, food, sugars, computers, etc. Besides this, every living thing in this world is organic. Even, inorganic substances like rocks, air, water, and metals usually contain organic matter.

2) Inorganic Chemistry

This branch deals with the study of elements and their compounds other than hydrocarbons. For example, the study of carbon but not compounds in which carbon is bonded with hydrogen (compounds other than organic compounds). We can say that it is opposite to that of organic chemistry where we study compounds containing carbon atoms bonded to hydrogen atoms. The father of inorganic chemistry is Alfred Werner.

In inorganic chemistry, we study the behaviour, properties, and physical and chemical characteristics of inorganic compounds. The inorganic compounds include crystal structures, minerals, metals, catalysts and most elements. So, it covers all materials which are not organic or which can be termed as non-living substances. The inorganic compounds that lack carbon-hydrogen bonding include metals, salts, chemical substances, and more. There are around 100000 inorganic compounds on the Earth.

Applications of inorganic chemistry:

Inorganic compounds have numerous uses or applications such as they can be used as catalysts, coatings, catalysts, surfactants, fuels, medicines, and more. For example;

• Ammonia: It is an ideal source of nitrogen when used as fertilizer. It is also a widely used inorganic chemical for the production of fibres, plastics, polyurethanes (chemical-resistant adhesives, coatings, etc.), hydrazine (used in the fuel of rockets and jets) and explosives, etc.
• Chlorine: It is used to produce polyvinyl chloride (used in the production of pipes, furniture, etc.), and to produce agrochemicals (fertilizers, insecticides, water and soil treatment or sterilization) and to produce pharmaceuticals, and more.
• Titanium dioxide: It is an oxide of titanium, which exists naturally. It is used as a white powder pigment in paints, coatings, plastics, cosmetics, etc. Besides this, due to its ultraviolet light resistance properties, it can be used in photocatalysts.

3) Physical Chemistry

It deals with the study of rules and principles of reactions. The father of physical chemistry is Wilhelm Ostwald. It is the study of the behaviour of matter on a molecular and atomic level and how chemical reactions occur. It allows physical chemists to understand the formation of complex structures and to research and develop potential uses of new materials.

It focuses on the physical structure of the chemical compounds or substances and the way they react with other substances. So, it also includes physical changes that occur during chemical reactions.

It also makes use of concepts of physics to analyse the chemical properties of substances and their ability to react. We can say that physical chemistry uses both physics and chemistry to study the physical properties of substances.

Importance or applications of physical chemistry:

• It helps to understand other branches of chemistry. It helps in understanding the changes in entropy that occur during chemical reactions and are necessary for the reactions to proceed further.
• It provides an explanation for the ideas proposed in organic chemistry related to the reacting ability of organic compounds.
• It helps understand the structure and behaviour of transition metal complexes, organometallic compounds, zeolites (play an important role in catalysis), and biological macromolecules like DNA, RNA, proteins, etc.

Some examples of physical chemistry in our daily life:

• In our body, the cells use energy which is released when the chemical Adenosine Triphosphate (ATP) breaks down into Adenosine diphosphate (ADP) and a Phosphate molecule.
• The cars give better mileage with higher octane fuels as the heat of combustion increases in the chemical reaction.
• The Neon lights glow due to the flow of current or electricity. The current causes the excitation of electrons that are located in different energy levels around an atom. So, it also involves physical chemistry.

4) Analytical Chemistry

It involves the study of the separation, identification and quantification of elements and compounds. It may use classical methods and modern methods or instruments. It also analyses the reaction of two compounds that react to form a third compound and the amount of reactants that reacted to form the third compound.

We can say that it involves the following methods:

• Process of separation: The chemical components, which are to be analysed, are isolated from a mixture.
• Identification: The chemical components are identified after separation through qualitative analysis.
• Quantification: The concentration or amount of the components in a sample is determined by using quantitative analysis methods.

Methods used in Analytical Chemistry

The methods, which are used in analytical chemistry, are divided into classical and instrumental methods.

Classical Methods:

There are various classical methods to check the presence or absence of a compound in the given sample or substance such as;

• Acid test for gold in which the test piece is rubbed on a stone, which leaves a visible mark. Nitric acid is applied to the mark, if the mark disappears, the test piece is not gold, if the mark remains, it is gold.
• Kastle-Meyer test, which uses phenolphthalein to detect the presence of haemoglobin in a sample.
• Flame test, which checks the presence of elements in a sample by exposing the sample to a flame. The change in the colour of the flame is observed to identify the elements.
• Gravimetric analysis, which is used to find out the amount of water in a hydrate. The hydrate is heated then the weight of the water lost is calculated.

Instrumental Methods:

• Spectroscopy: In this method, the interaction between electromagnetic radiation and particles of the given sample is measured.
• Electrochemical analysis: The sample is placed in an electrochemical cell. Then the current passed through the sample is measured.
• Calorimeter: It is used to measure the heat of a chemical reaction. In this method, the heat produced when the sample reacts in a chemical reaction is measured.

Analytical chemistry is further divided into two sub-branches, which are as follows;

i) Quantitative analysis: It involves the measurement of absolute or relative quantity or concentration of one or more components present in the given sample.

For example; when the chemists study a solid substance, first they use qualitative methods to identify the compound present in the sample. Then they use the quantitative analysis methods to find out the exact amount of that compound present in the sample. Some examples of quantitative analysis are Gravimetric Analysis and Volumetric analysis.

ii) Qualitative Analysis:

As the name suggests, it involves the determination of the quality of a particular compound irrespective of its quantity. So, in this method, only quality is measured, quantity is not measured. For example, a change in colour occurs or not in a chemical reaction. Various qualitative analysis methods are used in salt analysis to identify the cations or anions of inorganic salts.

Applications of analytical chemistry:

• It is used to determine the shelf life of medicines in pharmaceutical companies.
• It checks the adulterants in the drugs.
• It can check the concentrations of minerals and nutrients in the soil required for the proper growth of plants.
• In chromatography, it is used to classify the blood samples of an individual.
• It can also check the presence of impurities in the food samples.
• It is used in checking the amount of cholesterol and glucose in the blood samples.
• It is also a part of forensic science, clinical analysis and environmental analysis.

5) Bio-chemistry

It deals with the study of chemical processes and changes occurring in living organisms or biological systems. It also studies the structure, composition and chemical reactions of substances or chemicals found in living systems.

It uses chemistry along with biology to better understand the biological processes such as digestion, respiration, excretion, etc., and also studies biomolecules like carbohydrates, lipids, proteins, acids, DNA, RNA, etc. The father of biochemistry is Carl Neuberg. The term 'biochemistry' was also given by him.

Biochemistry is further divided into the following main branches;

• Molecular genetics: It deals with the study of genes. It can be associated with genetic engineering.
• Agricultural biochemistry: It deals with the use of biochemistry to improve agriculture production.
• Molecular biochemistry: This branch studies macromolecules like nucleic acids (DNA, RNA), proteins, enzymes, amino acids, and more.
• Immunochemistry: It is the branch of biochemistry that studies the chemicals and chemical reactions associated with the immune system.
• Clinical biochemistry: It involves the study or measurement of natural or unnatural chemicals found in blood, urine and other fluids found in the human body.

Applications or importance of biochemistry

• It is used to understand the chemical processes that occur during the transformation of food particles into energy.
• It allows in understand the catalytic functions of enzymes.
• It is used to create high yielding varieties of plants such as crops and fruits.
• It is used to produce various drugs, medicines, supplements, etc.
• It is used to identify chemicals found in blood, urine, and other body fluids.
• It is used to modify genes to produce more diseases-resistance species.

Besides the above five branches, there are various other branches of chemistry that were introduced over time, such as industrial chemistry, nuclear chemistry, and more.

• Industrial Chemistry

It is the study of industrial processes, which are used to convert raw material and their derivatives into products that are beneficial for humans. So, this branch of chemistry involves the study of physical and chemical methods and their use in the production of products on a large scale from raw materials. So, it involves the transformation of raw material and their derivatives into beneficial products.

Applications of industrial chemistry:

It is used to produce various beneficial products. For example; nitrogen and hydrogen are used to form ammonia (N₂ + 3H₂ → 2 NH₃), which is used in the fertilizer industry to form ammonium nitrate fertilizer. Similarly, petroleum obtained from the earth's crust is converted to ethylene which is a derivative and is converted to polyethylene.

• Nuclear Chemistry

It focuses on the changes and properties of atomic nucleus whereas traditional chemistry mainly focuses on the electronic structure of atoms. We can say that it studies the effect of changes in the atomic nucleus on the physical and chemical properties of atoms or elements or molecules. Besides this, it also studies the radiations, nuclear reactions and their applications.

Applications of nuclear chemistry

• It offers various applications in medicine, industry, agriculture, research, and more.
• It is used to treat and diagnose diseases. It can provide images from the inside of the human body and can kill tumour cells without affecting the healthy cells.
• It is used to produce electricity by using the heat produced from a nuclear reaction.
• It helps prevent the growth of insects in agricultural fields.
• It is used to sterilize medical equipment, and other items like syringes, heart valves, surgical gloves, etc., in hospitals.
• It helps in the space exploration programs as it can be used to provide electricity to spacecraft through unmanned generators fitted in the spacecraft.
• It can provide the large amount energy required for desalination of water, a process in which salt is removed from saltwater to make it drinkable.