Why can water be a Lewis base?

1 Answer
May 15, 2018

A Lewis base is an electron pair donor. Water has one active lone pair that can do so (forget about having four-coordinate oxygen).

In this reaction, water is the Lewis base, #"H"^(+)# is the Lewis acid (not #"NH"_4^(+)#). Water donates the electron pair, and the #"H"^(+)# on #"NH"_4^(+)# accepts that electron pair to make a bond.

#"NH"_4^(+)# is then a Brønsted-Lowry acid, being a proton donor, and water is then also the Brønsted-Lowry base, being a proton acceptor.

The way I drew hydronium is a bit misleading. What is the actual molecular geometry of hydronium?