Question

Which one of the following is incorrect?

• A. Boron halides are all monomeric while those of Al are dimeric.
• B. Boron halides and aluminium halides exist as monomeric halides.
• C. Boron halides and aluminium halides are Lewis acids.
• D. $B_2O_3$ alone is acidic while $Al_2O_3$ is amphoteric.

Answer 1

Answer: (B)

Boron halides and aluminium halides exist as monomeric halides.

Answer 2

Since the boron atom is not surrounded by an octet of electrons, boron halides like BF3 or BCl3 are electron-deficient compounds. They thus have a propensity to operate as potent Lewis acids by taking electrons from several Lewis bases to produce persistent acid-base adducts, serving as catalysts for numerous significant chemical processes.

The bond angle of boron halides, which have a planar structure and a sp2 hybridization, is 120°. The experimentally discovered BX bond lengths, however, are shorter than the values predicted from the halogens' and boron's covalent single bond radii.

In addition to the Lewis acid-base reaction and the most common compounds featuring covalent bonds between a non-metal and a halogen, boron halides are subject to a variety of other reactions. Through hydrolysis processes, these substances react vehemently with water to produce boric acid and hydrogen halide. The broad response below can serve as a representation of this.