What is Chemistry
Chemistry is that branch of science that studies the composition, properties and interactions of matter. Chemists are interested in knowing how chemical transformations occur.
Antoine Lavoisier is known as the father of chemistry because he listed elements, found oxygen is crucial for combustion, described the properties of matter.
Prafulla Chandra Ray, an Indian chemist, was born Aug. 2, 1861. Ray is often referred to as the father of chemistry in India.
The four important branches of chemistry are the following.
Inorganic Chemistry deals with study of elements and their compounds.
Organic Chemistry is that branch which deals with carbon compounds.
Physical Chemistry is concerned with the explanation of fundamental principles.
Analytical Chemistry is the branch of chemistry which is concerned with qualitative and quantitative analysis of chemical substances.
Chemistry plays an important role in meeting human needs for food, health care products and other materials aimed at improving the quality of life. Many life saving drugs such as cisplatin and taxol, are effective in cancer therapy and AZT (Azidothymidine) used for helping AIDS victims, have been isolated from plant and animal sources or prepared by synthetic methods.
With a better understanding of chemical principles it has now become possible to design and synthesise new materials, develop theories that can solve environmental problems.
One such problem is the management of the Green House gases like methane, carbon dioxide etc. Understanding of bio-chemical processes, use of enzymes for large-scale production of chemicals and synthesis of new exotic materials are some of the intellectual challenges for the future generation of chemists. A developing country like India needs talented and creative chemists for accepting such challenges.
Every substance has unique or characteristic properties. These can be classified in two types, Physical properties and Chemical properties.
Physical properties are those properties which can be measured or observed without changing the composition of the substance. Examples are colour, odour, melting point, boiling point, density etc.
Chemical properties require a change to occur. Then a new substance is formed with a different composition. Thus all properties change including physical properties.
Differences Between Physical and Chemical Change
| Physical Change | Chemical Change |
| When a substance undergoes a physical change, its composition remains the same despite its molecules being rearranged. | When a substance undergoes a chemical change, its molecular composition is changed entirely. Thus, chemical changes involve the formation of new substances. |
| Physical change is a temporary change. | It is a permanent change. |
| A Physical change affects only physical properties i.e. shape, size, odour, physical state, density, volume etc. changed and chemical properties remain unchanged . | A change both physical and chemical properties of the substance including its composition occurs. |
| A physical change involves very little to no absorption of energy. | During a chemical reaction, absorption and evolution of energy take place. |
| Some examples of physical change are freezing of water, melting of wax, boiling of water, etc. | A few examples of chemical change are digestion of food, burning of coal, rusting, etc. |
| Generally, physical changes do not involve the production of energy. | Chemical changes usually involve the production of energy (which can be in the form of heat, light, sound, etc.) |
| In a physical change, no new substance is formed. | A chemical change is always accompanied by one or more new substance(s). |
| Physical change is easily reversible i.e original substance can be recovered. | Chemical changes are irreversible i.e. original substance cannot be recovered. |
Greek Letters & Their Names
| α alpha
β beta γ gamma δ delta ζ zeta η Eta Ө theta Ι iota k kappa λ lambda µ mu υ nu π pi ρ rho σ sigma τ tau Φ phi χ chi ψ psi ω omega |