Lewis Bases are
i. Neutral species having at least one lone pair of electrons :
For example, ammonia, amines, alcohols, etc. act as Lewis bases because they contain a pair of electrons.
ii. Negatively charged species or anions :
For example, chloride, cyanide, hydroxide ions, etc. act as Lewis bases.
It may be noted that all Bronsted bases are also Lewis bases but all Bronsted acids are not Lewis acids.
