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Le Chatelier's principle (pronounced UK: / lə ʃæˈtɛljeɪ / or US: / ˈʃɑːtəljeɪ / ), also called Chatelier's principle (or the Equilibrium Law ), [ 1][ 2] is a principle of chemistry used to predict the effect of a change in conditions on chemical equilibrium. [ 3] The principle is named after French chemist Henry Louis Le Chatelier ...
e. In physics and chemistry, the law of conservation of mass or principle of mass conservation states that for any system closed to all transfers of matter and energy, the mass of the system must remain constant over time, as the system's mass cannot change, so the quantity can neither be added nor be removed. Therefore, the quantity of mass is ...
Arrhenius equation. In physical chemistry, the Arrhenius equation is a formula for the temperature dependence of reaction rates. The equation was proposed by Svante Arrhenius in 1889, based on the work of Dutch chemist Jacobus Henricus van 't Hoff who had noted in 1884 that the van 't Hoff equation for the temperature dependence of equilibrium ...
t. e. The second law of thermodynamics is a physical law based on universal empirical observation concerning heat and energy interconversions. A simple statement of the law is that heat always flows spontaneously from hotter to colder regions of matter (or 'downhill' in terms of the temperature gradient).
Hund's rules. In atomic physics and quantum chemistry, Hund's rules refers to a set of rules that German physicist Friedrich Hund formulated around 1925, which are used to determine the term symbol that corresponds to the ground state of a multi-electron atom. The first rule is especially important in chemistry, where it is often referred to ...
Avogadro's law states that "equal volumes of all gases, at the same temperature and pressure, have the same number of molecules ." [ 1] For a given mass of an ideal gas, the volume and amount (moles) of the gas are directly proportional if the temperature and pressure are constant. The law is named after Amedeo Avogadro who, in 1812, [ 2][ 3 ...
Valence shell electron pair repulsion ( VSEPR) theory ( / ˈvɛspər, vəˈsɛpər / VESP-ər, [ 1]: 410 və-SEP-ər[ 2]) is a model used in chemistry to predict the geometry of individual molecules from the number of electron pairs surrounding their central atoms. [ 3] It is also named the Gillespie-Nyholm theory after its two main developers ...
Bent's rule. Shape of water molecule showing that the real bond angle 104.5° deviates from the ideal sp 3 angle of 109.5°. In chemistry, Bent's rule describes and explains the relationship between the orbital hybridization and the electronegativities of substituents. [ 1][ 2] The rule was stated by Henry A. Bent as follows: [ 2] Atomic s ...