electron pairing

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• Electron pair — In chemistry, an electron pair consists of two electrons that occupy the same orbital but have opposite spins.Because electrons are fermions, the Pauli exclusion principle forbids these particles from having exactly the same quantum numbers.… …   Wikipedia

• 18-Electron rule — The 18 electron rule is a rule of thumb used primarily in transition metal chemistry for characterizing and predicting the stability of metal complexes. Valence shells of a transition metal can accommodate 18 electrons: 2 in each of the five d… …   Wikipedia

• chemical bonding — ▪ chemistry Introduction       any of the interactions that account for the association of atoms into molecules, ions, crystals, and other stable species that make up the familiar substances of the everyday world. When atoms approach one another …   Universalium

• superconductivity — superconduction /sooh peuhr keuhn duk sheuhn/, n. superconductive /sooh peuhr keuhn duk tiv/, superconducting, adj. superconductor /sooh peuhr keuhn duk teuhr/, n. /sooh peuhr kon deuhk tiv i tee/, n. Physics. the phenomenon of almost perfect… …   Universalium

• Superconductivity — is a phenomenon occurring in certain materials generally at very low temperatures, characterized by exactly zero electrical resistance and the exclusion of the interior magnetic field (the Meissner effect).The electrical resistivity of a metallic …   Wikipedia

• chemistry — /kem euh stree/, n., pl. chemistries. 1. the science that deals with the composition and properties of substances and various elementary forms of matter. Cf. element (def. 2). 2. chemical properties, reactions, phenomena, etc.: the chemistry of… …   Universalium

• Complex (chemistry) — The term complex in chemistry is usually used to describe molecules or ensembles formed by the combination of ligands and metal ions. Originally, a complex implied a reversible association of molecules, atoms, or ions through weak chemical bonds …   Wikipedia

• Coordination complex — Cisplatin, PtCl2(NH3)2 A platinum atom with four ligands In chemistry, a coordination complex or metal complex, is an atom or ion (usually metallic), bonded to a surrounding array of molecules or anions, that are in turn known as ligands or… …   Wikipedia

• Hyperconjugation — In organic chemistry, hyperconjugation is the interaction of the electrons in a sigma bond (usually C–H or C–C) with an adjacent empty (or partially filled) non bonding p orbital or antibonding π orbital or filled π orbital, to give an extended… …   Wikipedia

• Radical clock — In chemistry, a radical clock is a compound that assists in the indirect methodology to determine the kinetics of radical molecule reactions. This involves a unimolecular radical reaction with a known rate constant competing against a bimolecular …   Wikipedia

• Physical Sciences — ▪ 2009 Introduction Scientists discovered a new family of superconducting materials and obtained unique images of individual hydrogen atoms and of a multiple exoplanet system. Europe completed the Large Hadron Collider, and China and India took… …   Universalium