How can I classify each species as either a Lewis acid or a Lewis base for: #Fe_3^+, BH_3, NH_3 and F^-#?

1 Answer
Antoine
May 2, 2015

Lewis acids:
#Fe^(3+)#
#BH_2#

Lewis bases:
#NH_3#
#F^-#

Lewis acids(or electrophiles) are electron-deficient species. We can also say that they have a net positive charge.

#BH_3# is a lewis acid because Boron only has 3 valence electrons and so it forms only three covalent bonds #"H"#, instead of four. So we say it lacks 2 more electrons to gain a complete octet!

Lewis bases(or nucleophiles) are electron-rich species. They have a net negative charge.

#NH_3# is a lewis base because #"Nitrogen"# forms only three bond with #"H"# and so has a lone pair of electrons, and so it has a net negative charge.

Related questions
See all questions in Main Characterstics or Lewis/Bronsted Definition
Impact of this question
8871 views around the world
You can reuse this answer
Creative Commons License