The photochemistry, a subdiscipline of chemistry is the study of interactions between atoms, molecules small, and light (or electromagnetic radiation ).
As in most scientific disciplines, photochemistry uses the metric system for your measurements. Important units and constants that appear regularly include meters, seconds, hertz , joules, moles , the universal constant of ideal gases R, and Boltzmann constant . These units and constants are also integrated into the field of physical chemistry .
The first law of photochemistry, known as the Grotthus-Draper law (for chemists Theodor Grotthuss and John W. Draper ), states that light must be absorbed by a chemical that results in a photochemical reaction.
The second law of photochemistry, the Stark-Einstein law, states that for every photon of light absorbed by a chemical system, only one molecule is activated for a photochemical reaction. This is also known as the law of fotoequivalencia and was derived by Albert Einstein at the time that quantum theory of light was being developed.
The photochemistry can be introduced as a reaction that comes with the absorption of light. Normally, reaction (not just a photochemical reaction) occurs when a molecule gains activation energy needed to experience changes . An example of this is the combustion of gasoline (a hydrocarbon) into carbon dioxide and water. This is a chemical reaction in which one or more molecules or chemical species are transformed into others. For this reaction is carried out must be provided activation energy. The activation energy is provided in the form of heat or spark. In the case of photochemical reactions, is the light that provides the activation energy.
The absorption of a photon of light by a reactant molecule may also allow a reaction to occur not only bringing the molecule to the necessary activation energy, but also by changing the symmetry of the electronic configuration of the molecule, reaction path allowing otherwise inaccessible, as described by the selection rules Woodward-Hoffman. Cycloaddition reaction of 2 +2 is an example of a pericyclic reaction that can be analyzed using these rules or the related molecular orbital theory.
As in most scientific disciplines, photochemistry uses the metric system for your measurements. Important units and constants that appear regularly include meters, seconds, hertz , joules, moles , the universal constant of ideal gases R, and Boltzmann constant . These units and constants are also integrated into the field of physical chemistry .
The first law of photochemistry, known as the Grotthus-Draper law (for chemists Theodor Grotthuss and John W. Draper ), states that light must be absorbed by a chemical that results in a photochemical reaction.
The second law of photochemistry, the Stark-Einstein law, states that for every photon of light absorbed by a chemical system, only one molecule is activated for a photochemical reaction. This is also known as the law of fotoequivalencia and was derived by Albert Einstein at the time that quantum theory of light was being developed.
The photochemistry can be introduced as a reaction that comes with the absorption of light. Normally, reaction (not just a photochemical reaction) occurs when a molecule gains activation energy needed to experience changes . An example of this is the combustion of gasoline (a hydrocarbon) into carbon dioxide and water. This is a chemical reaction in which one or more molecules or chemical species are transformed into others. For this reaction is carried out must be provided activation energy. The activation energy is provided in the form of heat or spark. In the case of photochemical reactions, is the light that provides the activation energy.
The absorption of a photon of light by a reactant molecule may also allow a reaction to occur not only bringing the molecule to the necessary activation energy, but also by changing the symmetry of the electronic configuration of the molecule, reaction path allowing otherwise inaccessible, as described by the selection rules Woodward-Hoffman. Cycloaddition reaction of 2 +2 is an example of a pericyclic reaction that can be analyzed using these rules or the related molecular orbital theory.
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