[Chemistry] Importance and Scope of Chemistry


Chemistry is the science of matter.

Anything which has mass and occupies space is matter.

The word “chemistry” is derived from the Arabic word “Al-Kemia” which means the art of transformation.


Chemistry is the branch of science which deals with the study of matter, its composition, structure, properties, behavior, and the interaction of matter in the form of reactions.


  • Chemistry has been practiced subconsciously by humans since the beginning of civilization.
  • The history of chemistry spans from ancient history to the present-day world. Around 1000 BC, civilizations in different parts of the world were using technologies that would eventually become the basis for the evolution of branches of chemistry.
  • Examples include extraction of metals from ores, production of glazes and pottery, fermentation of wine and beer, extraction of chemicals from plants for use as perfumes and medicinal purposes, production of soap from fat, making glass, and production of alloys e.g bronze.
  • Alchemy, which was practiced by the Arabs, served as a protoscience to modern chemistry.
  • Alchemists, by performing experiments and recording the results, set the stage for modern chemistry.
  • Although Alchemy laid the basis for modern chemistry, it however was rendered unsuccessful in explaining the nature of matter and its transformations.
  • The first major contribution to the field of chemistry was made by Jabir-Ibn-Hayyan who is regarded as the father of chemistry
  • Jabir’s works contain the oldest known systematic classification of chemical substances and the oldest known instructions for deriving an inorganic compound from organic substances by chemical means.
  • He also described various processes such as crystallization and distillation and is credited with the use of twenty different now-basic chemical laboratory equipment.
  • The distinction between Chemistry and Alchemy came into play when a clear differentiation was provided by an English Philosopher, Robert Boyle in his book published under the name The Sceptical Chymist (1661).
  • Robert Boyle set the stage for modern chemistry which over the years, through the contribution of various scientists, has become a major discipline in science and almost inseparable from human life.

[Chemistry] Laws of Chemical Combination


  • As we have argued before that chemistry is the science of matter.
  • Matter is always transforming from one state to another state. These transformations occur as a result of interaction among different types of matter.
  • This interaction among various forms of matter is termed as a chemical reaction



A process by which one or more substances (reactants) interact with each other leading to the formation of one or more different substances (products).

  • Chemical reaction occurs by the re-arrangement of constituent atoms and molecules of the reactants.
  • Chemical reaction results in the formation of a product that is chemically different than the reactants.

[Chemistry] Dalton’s Atomic Theory


John Dalton presented the atomic theory which was the first to describe matter as a divisible particle and established that matter is in fact composed of further small particles called atoms.


  • The idea of matter being made up of small particles is very old and almost dates back to the pre-historic civilizations of Greece and India.
  • The term atom is in fact derived from the Greek word “ATOMOS” meaning indivisible and was coined by Greek philosophers Leucippus and Democritus.
  • In the 18th century Laws of conservation of mass and law of definite proportions were coined by Lavoisier and Proust

[Chemistry] Classification of Matter (Element, Atom, Molecule, Compound, Mixture)


Anything which occupies space and has mass is termed as matter. Matter can be broadly classified into pure substances and mixtures.


Pure substances are matter having an invariable chemical composition and distinct properties.

It further consists of

  • elements
  • compounds


Matter consisting of two or more pure substances that retain their individual identities and can be separated by physical methods

Mixtures further consist of

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[Chemistry] Atomic number and Atomic Mass


  • As we know, an atom consists of electron protons and neutrons.
  • The protons and neutrons reside within the nucleus and are collectively called nucleons.
  • The protons carry a positive charge whereas neutrons are electrically negative.
  • The electrons revolve around the nucleus in specific pathways called orbits or shells.
  • The electrons are negatively charged particles.

An atom as a whole is electrically stable with no net charge. This means that the positive charge imparted by the protons is neutralized by the negatively charged electrons. This is only possible when the electrons and protons are equal in number.


The number of protons contained within the nucleus of an atom is called atomic number

  • Atomic number is also known as proton number
  • Atomic number is denoted by the symbol Z.
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[Chemistry] Mole


A mole of a substance is the amount that contains the same number of units (atoms, molecules or ions) as the number of carbon atoms in 12 grams of Carbon-12.


  • We know that atom is an extremely small particle.
  • The mass of an individual atom is a very small quantity and is not feasible for calculation.
  • It is impossible to weight individual atoms or even small groups of atoms directly.
  • Therefore, the concept of mole is used. One mole of a substance is the relative atomic/molecular mass expressed in grams.
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[Chemistry] Isotopes, Isobars , % Composition, Empirical & Molecular Formulae


Isotopes are atoms of the same element having different atomic masses.


  • All atoms of the same element possess identical number of protons. However, they may have different number of neutrons.
  • This phenomenon is termed as isotopy and the atoms of the same element having the same number of protons but different number of neutrons are termed as isotopes.
  • The isotopes of the same element have the same chemical properties due to possession of identical number of electrons.


  • Hydrogen possess three isotopes which are; Protium, Deuterium and tritium.
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[Chemistry] Chemical Reaction


Chemical reaction is a process in which two or more substances interact with each other resulting in the formation of two or more new substances.


A chemical reaction mainly consists of two components

  • Reactants
  • Products


Reactants are the substances present at the start of a chemical reaction.

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[Chemistry] Stoichiometry


Stoichiometry is the branch of chemistry which tells us about the quantitative relationship between reactants and products in a balanced chemical equation.


In order to perform stoichiometric calculations, the following assumptions must be taken into account

  1. All the reactants are completely converted into products
  2. No side reaction occurs


While doing stoichiometric calculations, the following laws are obeyed

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[Chemistry] Dual Nature Of Matter And Light


  • Plank’s quantum theory tells us that light shows a dual character. It behaves both as a material particle and as a wave.
  • This idea was extended to matter in 1924 by Louis De-Broglie.


  • According to De-Broglie, all matter particles in motion have a dual character.
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