what is a nucleophile

A nucleophile is a chemical species that donates an electron pair to form a new covalent bond/Chapter_7._Reactivity_and_Electron_Movement/7.1_Nucleophiles_and_Electrophiles). All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Nucleophiles are Lewis bases because they donate electrons. Nucleophilicity refers to a substances nucleophilic character and is often used to compare the affinity of atoms. Examples of nucleophiles include anions such as Cl−, hydroxide ion (OH−), cyanide ion (CN−), ammonia (NH3), and water. Nucleophilicity is closely related to basicity, but nucleophilicity is a kinetic property, which relates to rates of certain chemical reactions, while basicity is a thermodynamic property that relates to an equilibrium state.