electrophiles & nucleophiles

• in reactions involving heterolytic bond fission, attacking groups are classified as nucleophiles or electrophiles
• electrophiles are a substance which can accept a pair of electrons
• electrophiles are a positively charged ion or a neutral molecule that is electron deficient
• electrophiles are attracted towards an area of high electron density with a negative charge
• nucleophiles are a lone pair electron donor
• nucleophiles are molecules or negatively charged ions that have at least one lone pair of electrons
• nucleophiles are attracted to an electron deficient centre, where it donates its electron pair to form a new covalent dative bond
• nucleophiles will seek out electron deficient sites on organic molecules
• polar molecules, such as ammonia, have both nucleophile and electrophile centres as they contain areas which are both positively and negatively charged
• substitution reaction

  an atom or group of atoms is replaced by another atom or group of atoms
• addition reaction

  two molecules join together to make one larger molecule
• elimination reaction

  a small molecule is removed from an organic compound