Question

what are Lewis acids.

Answer 1

Lewis acids are

i. Molecules in which the central atom has incomplete octet :

BF₃ , BCI₃ , AICI₃ , MgCI₂ , BeCI₂ etc.

ii. Simple cations :

Na⁺ , K⁺ , Ca²⁺ , H⁺ , Ag⁺  etc.

iii. Molecules in which the central atom has empty d-orbitals :

The central atom of the halides such as SiX₄ , GeX₄ , TiCI₄ , SnX₄ , PX₃ , PF₅ , SF₄ , SeF₄ , TeCI₄ etc. have vacant d-orbitals.

iv. Molecules having a multiple bond between atoms of dissimilar electronegativity :

Typical examples of molecules