nucleophile [no͞o′klē ə fīl΄, nyo͞o′klē ə fīl΄]n.an atom or molecule that has an affinity for atomic nuclei or that donates electrons to form a covalent bondnucleophilic [no͞o′klē əfil′ik, nyo͞o′klē əfil′ik]adj.
* * *nu·cle·o·phile (no͞oʹklē-ə-fīl', nyo͞oʹ-) n.A chemical compound or group that is attracted to nuclei and tends to donate or share electrons.
* * *Atom or molecule that contains an electron pair available for bonding and in chemical reactions therefore seeks a positive centre, such as the nucleus of an atom or the positive end of a polar molecule (see covalent bond; electric dipole).In the Lewis electron theory (see acid-base theory), advanced by the U.S. chemist Gilbert Lewis (1875–1946) in 1923, nucleophiles are by definition Lewis bases. Examples include the hydroxide ion (OH-), the ions of the halogens chlorine, bromine, and iodine (Cl-, Br-, and I-, respectively), ammonia (NH3), and water (H2O). See also base; electrophile.
* * *in chemistry, an atom or molecule that in chemical reaction seeks a positive centre, such as the nucleus of an atom, because the nucleophile contains an electron pair available for bonding. Examples of nucleophiles are the halogen anions (I-, Cl-, Br-), the hydroxide ion (OH-), the cyanide ion (CN-), ammonia (NH3), and water. Compare electrophile.
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