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A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. [1] When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an energy change as new products are generated.
Chemistry is the scientific study of the properties and behavior of matter. [1] It is a physical science within the natural sciences that studies the chemical elements that make up matter and compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during reactions with other substances.
In chemistry, a chemical oscillator is a complex mixture of reacting chemical compounds in which the concentration of one or more components exhibits periodic changes. They are a class of reactions that serve as an example of non-equilibrium thermodynamics with far-from-equilibrium behavior.
A single-displacement reaction, also known as single replacement reaction or exchange reaction, is an archaic concept in chemistry.It describes the stoichiometry of some chemical reactions in which one element or ligand is replaced by an atom or group.
The enthalpy of a chemical system is essentially its energy. The enthalpy change ΔH for a reaction is equal to the heat q transferred out of (or into) a closed system at constant pressure without in- or output of electrical energy. Heat production or absorption in a chemical reaction is measured using calorimetry, e.g. with a bomb calorimeter.
Some of the most persuasive evidence for the Great Oxidation Event is provided by the mass-independent fractionation (MIF) of sulfur. The chemical signature of the MIF of sulfur is found prior to 2.4–2.3 Ga but disappears thereafter. [36] The presence of this signature all but eliminates the possibility of an oxygenated atmosphere. [16]
U.N. investigators are compiling evidence on the development and use of chemical weapons by Islamic State extremists in Iraq after they seized about a third of the country in 2014, and are ...
A chemical bond resulted when a hook and eye connected. Pauling, however, wasn't satisfied with this archaic method and looked to the newly emerging field of quantum physics for a new method. In 1927, the physicists Fritz London and Walter Heitler applied the new quantum mechanics to the deal with the saturable, nondynamic forces of attraction ...