Aluminum chloride acts as a strong Lewis acid since :Cl: Al Cl Cl: AICI3 is a covalent compound. AICI3 is easily hydrolyzed. AICI3 is an electron deficient compound. AlCl3 is an ionic compound.
The Correct Answer and Explanation is:
The correct answer is AlCl3 is an electron deficient compound.
Explanation
A Lewis acid is defined as a chemical species that can accept a pair of electrons from a Lewis base (an electron pair donor). To understand why aluminum chloride (AlCl3) is a strong Lewis acid, we must examine its electronic structure.
As shown in the provided Lewis structure, the central aluminum (Al) atom forms a single covalent bond with each of the three chlorine (Cl) atoms. Each covalent bond consists of two shared electrons. Therefore, the central aluminum atom has a total of 3 bonds × 2 electrons/bond = 6 valence electrons in its outer shell.
According to the octet rule, atoms are most stable when they have a full outer shell of eight valence electrons. Since the aluminum atom in AlCl3 only has six valence electrons, it has an incomplete octet. This makes the molecule “electron deficient.”
Because it is electron deficient, the aluminum atom has a vacant p-orbital and a strong tendency to accept a pair of electrons to achieve a more stable octet configuration. This ability to readily accept an electron pair is the defining characteristic of a Lewis acid. The significant electron deficiency of the aluminum atom makes AlCl3 a particularly strong Lewis acid.
While it is true that AlCl3 is a covalent compound and is easily hydrolyzed, these are not the fundamental reasons for its Lewis acidity. Its covalent nature describes its bonding, and its hydrolysis is a reaction that occurs because it is a strong Lewis acid (with water acting as the Lewis base). The compound is not ionic; it features polar covalent bonds. The core reason for its acidic behavior is its electron deficient nature.
