Basic Concepts of Chemistry

The advancement of science and technology has actually offered us a lot of facilities in everyday life. Imagine the role and importance of petrochemical products, medicines, and drugs, soap, cleaning agents, paper, plastics, paints and pigments, insecticides, pesticides which all are the fruit of the chemistry.

The advancement of the chemical market has actually likewise produced toxic wastes, polluted water, and polluted air around us. On the other hand, chemistry also provides understanding and techniques to improve our health and environment and to explore and to save natural resources.


Chemistry, the science that deals with the properties, composition, and structure of substances, the changes they go through, and the energy that is emancipated or absorbed during these processes.

Branches of Chemistry

Chemistry is divided into the following main branches: physical chemistry, organic chemistry, inorganic chemistry, biochemistry, industrial chemistry, nuclear chemistry, environmental chemistry, and analytical chemistry.

Physical Chemistry

Physical Chemistry is specified as the branch of chemistry that handles the relationship between the composition and physical properties of matter in addition to the changes produced in them.

The properties such as the structure of atoms or formation of molecules, the behavior of gases, liquids, and solids, and the research study of the effect of temperature level or radiation on the matter are studied under this branch.

Organic Chemistry

Organic Chemistry is the study of covalent compounds of carbon and hydrogen (hydrocarbons) and their derivatives. Organic substances are present naturally as well as manufactured in the laboratories. Organic chemistry determines the structure and properties of these naturally occurring in addition to synthesized compounds. The scope of this branch covers petroleum, petrochemicals, and pharmaceutical industries.


Inorganic Chemistry

Inorganic chemistry deals with the study of all elements and their substances except those of carbon and hydrogen (hydrocarbons) and their derivatives. It has a variety of applications in the chemical industry such as glass, cement, ceramics, and metallurgy (extraction of metals from ores).



It is the branch of chemistry in which we study the structure, composition, and chemical reactions of substances present in living organisms. It covers all chemical reactions and processes taking place in living organisms, such as synthesis and metabolic processes of biomolecules like carbohydrates, proteins, and fats.

Biochemistry emerged as a separate discipline when researchers started to study how living things get energy from food or how the fundamental biological modifications take place. Examples of applications of biochemistry are in the fields of medicine, food science, and farming.

Industrial Chemistry

The branch of chemistry that deals with the production of chemical compounds on an industrial scale is called industrial chemistry. It deals with the production of standard chemicals such as oxygen, chlorine, ammonia, caustic soda, nitric acid, and sulphuric acid.

These chemicals supply raw products for lots of other markets such as fertilizers, soap, textiles, agricultural products, paints and paper, and so on.

Nuclear Chemistry

Nuclear Chemistry is the branch of chemistry that deals with the radioactivity, nuclear procedures, and properties. The main purpose of this branch is to deal with atomic energy and its uses in daily life. It also involves the study of the chemical effects resulting from the absorption of radiation within animals, plants, and other products. It has vast applications in medical treatment (radiotherapy), conservation of food and generation of electrical power through atomic power plants, and so on.


Environmental Chemistry

It is the branch of chemistry in which we study parts of the environment and the results of human activities on the environment. Environmental chemistry is related to other branches like biology, geology, ecology, soil, and water. The understanding of chemical processes happening in the environment is required for its improvement and protection against pollution.

Analytical Chemistry

Analytical chemistry is the branch of chemistry that deals with the separation and analysis of a sample to determine its composition. The separation is carried out for qualitative and quantitative analysis. The qualitative analysis provides the identity of a substance (structure of chemical species).

On the other hand, the quantitative analysis identifies the amount of each component present in the sample. For this reason, in this branch, various techniques and instruments utilized for analysis are studied. The scope of this branch covers food, water, ecological and clinical analysis.

Fundamental Terms in Chemistry


Anything that has some mass and occupies some space is called matter. Whatever around you is matter. Matter exists in four states i.e.

  • Solid
  • Liquid
  • Gas
  • Plasma


The atom is the tiniest particle of an element, which can take part in a chemical reaction.


Earlier, it was believed that matter is comprised of simple, indivisible particles. Greek philosophers believed that matter could be divided into smaller and smaller sized particles to reach a standard unit, which might not be more sub-divided. Democritus (460-370 B.C.) called these particles Atomos, derived from the word “Atomos” means indivisible or to not cut. However, the ideas of Greek theorists were not based on speculative proofs.

In the late 17th century, the quantitative research of the composition of pure compounds divulged that a few elements were the components of lots of different compounds. It was likewise investigated how elements combined to form compounds and how compounds could be broken down into their constituent elements.

In 1808, an English school teacher, John Dalton, recognized that the law of conservation of matter and the law of definite proportions could be explained by the presence of atoms. He established an atomic theory; the primary postulate of which is that all matter is made up of atoms of different elements, which differ in their properties.

Examples: He (Helium), N(Nitrogen), Ne (Neon) etc.

Sub-Atomic Particles

The modern studies have clearly revealed that an atom is further composed of subatomic particles like electron, proton, neutron, hydron, neutrino, anti-neutrino, etc. More than 100 such particles are believed to exist in an atom. However, electron, proton, and neutron are regarded as the fundamental particles of atoms.



The electron is a subatomic particle, symbol e ⁻ or β ⁻, whose electrical charge is negative one elementary charge.


A proton is a subatomic particle, symbol p or p ⁺, with a positive electric charge of +1 e elementary charge.


The neutron is a subatomic particle, sign n or n ⁰, which has a neutral charge and a mass somewhat greater than that of a proton.

Protons and neutrons constitute the nuclei of atoms.

Atomic Number

The atomic number or proton number of a chemical element is the number of protons found in the nucleus of every atom of that element. It is represented by the sign ‘Z’.

For instance, all hydrogen atoms have 1 proton, their atomic number is Z= l. All atoms in carbon have 6 protons, their atomic number is Z= 6. Likewise, in oxygen all atoms have 8 protons having atomic number Z= 8, and sulphur having 16 protons reveals atomic number Z = 16.

Atomic Mass

The mass number is the sum of the number of protons and neutrons present in the nucleus of an atom. It is represented by the symbol ‘A’.

Formula: A= Z+ n.


The carbon atom has 6 protons and 6 neutrons, hence its mass number A= 12.


An element is a pure substance that can not be broken down by chemical methods, consisting of atoms which have identical numbers of protons in their atomic nuclei.

Example: Sodium, Copper, etc

Elements occur in nature in a free or combined state. All the naturally occurring components found in nature have different percentages in the earth’s crust, oceans, and atmosphere. Elements might be solids, liquids, or gases. The bulk of the elements exist as solids e.g. zinc, gold, and so on. There are really few components which happen in liquid state e.g. mercury and bromine. A couple of components exist as gases e.g. nitrogen, oxygen, chlorine, and hydrogen.

On the basis of their properties, elements are divided into metals, non-metals, and metalloids. About 80 percent of the elements are metals.