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Activation energy

Definition of the noun activation energy

What does activation energy mean as a name of something?


  1. the energy that an atomic system must acquire before a process (such as an emission or reaction) can occur

Alternative definition of the noun activation energy


  1. [chemistry, physics] The energy required to initiate a reaction. For example, the flame from the fuse of a firecracker provides a small initial amount of energy, after which the explosive reaction proceeds by itself, releasing a considerably larger quantity of energy. A small push given to a stable but top-heavy object may cause it to fall over; the potential energy released during the fall was present in the system all along but could not be realized as long as the object was upright and balanced.


Activation energy: In chemistry, activation energy is a term introduced in 1889 by the Swedish scientist Svante Arrhenius that means the minimum energy that must be input to a chemical system with potential reactants to cause a chemical reaction. Activation energy may also be defined as the minimum energy required to start a chemical reaction. The activation energy of a reaction is usually denoted by Eₐ and given in units of kilojoules per mole.

Printed dictionaries and other books with definitions for Activation energy

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Google previewA Dictionary of Science (2010)

by Elizabeth A. Martin

activated adsorption Adsorption that involves an activation energy. This occurs in certain cases of chemisorption. activated alumina ...

Google previewEncyclopedic Dictionary of Condensed Matter Physics (2004)

by Charles P. Poole, Jr.

ACTIVATION ENERGY 27 concentration of adsorbed molecules in the transient activated complex. This complex forms at the potential energy maximum along the most energetically favorable path of chemisorption. ACTIVATION ANALYSIS A ...

Google previewDictionary of Energy (1991)

by Hall

Activation Energy ACS American Chemical Society. ACTINIDES Elements with atomic numbers ranging from 89 to 103 (Table A-l). The elements in this series are radioactive and include the nuclear fuels and nuclear fertile materials.

Google previewConcise Dictionary of Materials Science (2002)

Structure and Characterization of Polycrystalline Materials by Vladimir Novikov

activation energy Additional free energy ...

Google previewEncyclopedia of Ecology (2014)

The minimum energy required, called activation energy, strictly depends on the reaction: for some reactions, this value is...

Google previewConcise Dictionary of Chemistry (2012)

by Editorial Board

is called the activation energy. The energy required to start a chemical reaction.

Google previewInternational Encyclopaedia of Engineering and Technology (2007)

by M N Doja

The activated complex is the structure at the maximum energy point along the reaction path; the activation energy is the difference between the energies of the activated complex and the reactants. An activated complex, often characterized by ...

Google previewDictionary of Chemistry

activation energy activated sludge process removes organic matter from sewage by saturating it with air and microbial organisms. activation ...

Google previewEncyclopedia of Fish Physiology (2011)

From Genome to Environment

Chemical reactions occur only when the energy of the molecular collision exceeds the activation energy (Ea) of the reaction (Figure 2). The Maxwell— Boltzmann distribution (Figure 3) can be used to describe the fraction of molecules with ...

Google previewThe American Heritage Science Dictionary (2005)

by American Heritage Dictionary

activation energy (ak'ta-va' shan) The least amount of energy needed for a chemical reaction to take place.

Google previewA Dictionary of Biology (2015)

by Elizabeth Martin, Robert Hine

activation energy Symbol Ea. The minimum energy required for a chemical reaction to take place. In a reaction, the ...

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