Question

Give Lewis’ definition for acids and bases.

Answer 1

Hint: Lewis definition for acid, and bases is related to the concept of coordinate covalent bond. It was helpful in the prediction of acid-base reactions. It was introduced after the theory of Bronsted-Lowry acids, and bases.

Complete step by step answer:
First, let us know about the theory of Bronsted-Lowry acids, and bases. It was related to hydrogen, and the hydroxide ions.
After this theory, Lewis introduced the concept of proton donors, and acceptors in terms of electrons.
According to his theory, the electron donor will be known as Lewis base, and electron acceptor will be termed as Lewis acid.
Now, we can say that when the Lewis acid, and Lewis base will react, they will form a coordinate covalent bond.
Then, in other terms we can define Lewis acid having vacant orbital acting as an electrophile, whereas Lewis base having lone-pair electrons acting as nucleophile.
Accordingly, electrophiles are the electron-attracting, and let us see the examples of molecules acting as Lewis acids. The cations, and the molecules with incomplete octet of electrons act as Lewis acids.
Talking about the nucleophiles, the presence of lone pairs will attack a positive charge. The molecules having lone pairs of electrons, and anions like hydroxide ion, cyanide ion will act as Lewis bases.
In the last we can conclude that Lewis theory for acids, and bases explained the formation of complex ions, or molecules on the basis of accepting, or donating electrons.

Note: Don’t get confused between Lewis acid, and Lewis base. It is a simple concept of donating, and accepting electrons, as explained. The theory by Lewis was helpful in expanding the acids, and bases, as if we consider the Bronsted theory, it was unable to explain about an acid, or base in the absence of hydrogen ions, or hydroxide ions.