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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.
Also acid ionization constant or acidity constant. A quantitative measure of the strength of an acid in solution expressed as an equilibrium constant for a chemical dissociation reaction in the context of acid-base reactions. It is often given as its base-10 cologarithm, p K a. acid–base extraction A chemical reaction in which chemical species are separated from other acids and bases. acid ...
Le Chatelier–Braun principle analyzes the qualitative behaviour of a thermodynamic system when a particular one of its externally controlled state variables, say , changes by an amount , the 'driving change', causing a change , the 'response of prime interest', in its conjugate state variable , all other externally controlled state variables remaining constant.
Examples of the exact sciences are mathematics, optics, astronomy, [3] and physics, which many philosophers from Descartes, Leibniz, and Kant to the logical positivists took as paradigms of rational and objective knowledge. [4] These sciences have been practiced in many cultures from antiquity [5] [6] to modern times.
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds.
The Avogadro constant, commonly denoted N A [1] or L, [2] is an SI defining constant with an exact value of 6.022 140 76 × 10 23 mol −1 (reciprocal moles). [3] [4] It is this defined number of constituent particles (usually molecules, atoms, ions, or ion pairs—in general, entities) per mole and used as a normalization factor in relating the amount of substance, n(X), in a sample of a ...
The two basic papers on this subject were among the top five chemistry and physics citations reported in ISI, Current Contents 1977 for the period of 1961–1977 with a total of 2450 references. In contrast to the Hartree–Fock-based semiempirical method counterparts (i.e.: MOPAC), the pi-electron theories have a very strong ab initio basis.
In the natural sciences, including physiology and engineering, a specific quantity generally refers to an intensive quantity obtained by the ratio of an extensive quantity of interest by another extensive quantity (usually mass or volume). If mass is the divisor quantity, the specific quantity is a massic quantity. [1]