Nucleophile: is negative so is attracted to positive parts of molecules
has an electron pair it can donate
example reaction: (OH)-ion added to halogenoalkane, displacing halide ion to for alcohol.
Electrophile: is positive so is attracted to negative parts of molecules, like a double bond (electron lover)
wants to accept an electron pair
example reaction: Hydrogen bromide (H is delta +ve due to dipolar bond) added to alkene (with double bond) to form halogenoalkane.