Question

According to Lewis acid-base concept, which is a correct statement?
A. Species in which central atom has completed octet cannot act as acid
B. All negatively charged ions are acid
C. Molecule in which the central atom has vacant orbitals acts as acid
D. All positively charged ions are bases.

Answer 1

Hint: To answer this question, you should have knowledge about the concept of the different bases of theory on which acid and base are classified. Remember, electron donors are the Lewis bases while the electron acceptors are the Lewis acids.

Complete step by step solution:
- According to the Lewis theory of acid-base reactions; Lewis acids and bases are described as the electron pair acceptors and the electron pair donors respectively.
- Thus, we can say that a Lewis base can donate a pair of electrons to a Lewis acid so as to form a product containing a coordinate covalent bond.
- Whereas, Lewis acids are the chemical species which have empty orbitals and can accept electron pairs from the Lewis bases. These chemical species can donate an electron pair to a given Lewis acid so as to form a “Lewis adduct”.
Therefore, we conclude that molecules in which a central atom has vacant orbitals will act as an acid.
So, the correct answer is “Option C”.

Note: It is important to note that, in Lewis acid the hydronium ion accepts the attacking electron pair to form bonds while in Lewis base, the hydroxyl ions donate electron pairs present over it to form a bond between itself and hydrogen ion.