A chemical reaction is a noun that primarily refers to the process in which one or more substances (reactants) undergo a transformation to produce new substances (products) with different chemical properties. It can be understood in various contexts:

Reactants and Products: In a chemical reaction, reactant molecules interact and rearrange their chemical bonds to form new molecules with different structures and properties, known as products.

Chemical Bonds: Chemical reactions involve the breaking and formation of chemical bonds between atoms, resulting in the creation of new compounds or molecules.

Exothermic and Endothermic: Chemical reactions may release energy to the surroundings (exothermic) or absorb energy from the surroundings (endothermic), depending on the overall change in bond energies.

Activation Energy: Most chemical reactions require an initial input of energy, known as activation energy, to initiate the reaction and overcome the energy barrier between reactants and products.

Synthesis and Decomposition: Synthesis reactions combine two or more substances to form a single product, while decomposition reactions break down a compound into simpler substances.

Single Replacement and Double Replacement: Single replacement reactions involve the exchange of atoms or ions between reactants, while double replacement reactions involve the exchange of ions between two compounds.

Rate of Reaction: Chemical reactions occur at different rates depending on factors such as temperature, concentration, surface area, and catalysts, which affect the frequency of collisions between reactant particles.

Chemical Equilibrium: In reversible reactions, chemical equilibrium is reached when the rates of the forward and reverse reactions are equal, resulting in a dynamic balance between reactants and products.

In summary, a chemical reaction is a noun that describes the process by which reactants undergo transformations to produce new substances with different chemical properties, involving changes in energy, types of reactions, reaction rates, and chemical equilibrium, with applications in chemistry, industry, and everyday life.

Examples of CHEMICAL REACTION in a sentence

  • A chemical reaction is a process that leads to the transformation of one set of chemical substances into another.
  • In a chemical reaction, bonds between atoms are broken and rearranged, resulting in the formation of new substances with different properties.
  • Chemical reactions are governed by the principles of conservation of mass and energy, meaning that the total mass and energy of the reactants must equal the total mass and energy of the products.
  • Factors such as temperature, pressure, concentration, and catalysts can influence the rate and outcome of a chemical reaction.
  • Common types of chemical reactions include synthesis (combination), decomposition, combustion, single replacement, and double replacement reactions.
  • Understanding chemical reactions is essential for fields such as chemistry, biology, and environmental science, where reactions play a central role in natural processes and human activities.
  • Chemical equations are used to represent chemical reactions, with reactants listed on the left side and products on the right side, separated by an arrow.
  • Studying chemical reactions allows scientists to develop new materials, improve industrial processes, and address environmental challenges.


The term chemical reaction has roots in Greek and Latin, reflecting its scientific origins. Here’s a breakdown of its etymology:

  • Greek Origins:
    • “Chemical”: The word “chemical” is derived from the Greek word “khēmeia” (χημεία), which originally referred to the practice of alchemy, an ancient proto-chemistry discipline.
    • “Reaction”: The word “reaction” comes from the Greek word “rhēxis” (ῥῆξις), meaning “a breaking off” or “a change.”
  • Latin Influence:
    • “Chemical”: The term “chemical” was adopted into Latin as “chemicus,” which retained its association with alchemy and the study of substances and transformations.
    • “Reaction”: The Latin word “reactio” also derives from the Greek “rhēxis” and carries similar meanings related to change or transformation.
  • Modern Usage:
    • Chemical reaction combines these Greek and Latin roots to describe a fundamental concept in chemistry: the transformation of one or more substances into different substances through the breaking and forming of chemical bonds.
    • This term is used universally in the field of chemistry to describe processes such as combustion, oxidation, reduction, synthesis, and decomposition.

Overall, the etymology of chemical reaction reflects its origins in Greek and Latin, its association with the study of substances and transformations, and its significance as a fundamental concept in modern chemistry.


  • Chemical change
  • Reaction
  • Chemical process
  • Chemical transformation
  • Chemical conversion
  • Chemical synthesis
  • Chemical alteration
  • Chemical decomposition


  • Physical change
  • Mechanical process
  • Biological reaction
  • Thermal equilibrium
  • Inert state
  • Physical transformation
  • Material conservation
  • Mechanical reaction


  • Reactants
  • Products
  • Catalyst
  • Activation energy
  • Exothermic
  • Endothermic
  • Stoichiometry
  • Equilibrium

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