How is bf3 an acid

Thus the boron atom needs a lone pair of electrons to give it an octet of electrons. Also, fluorine is highly electronegative, withdrawing electron density from the boron atom. This is represented in the electrostatic potential model at the upper-left, with flourine atoms in yellow-orange partial negative charge and boron in blue partial positive charge.

For all these reasons, the molecule BF 3 is a good acceptor of electrons and therefore a good Lewis acid. How happy would it be, if some other atom gladly donated their electron pair to share? Now what are we going to do if there is no Lewis base around? Well, initially boron will still be there, depleted of all its valence electrons by fluorine or nearly at least.

This is where fluorine discovers its charity side: All three fluorines donate just a tad of electron density so that the baby boron in the middle will stop crying. A lewis acid is defined as an electron pair acceptor. Also it contains only 6 electrons in outermost shell making it able to accept an electron pair to complete its octet. Thus it's lewis acid. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group.

Create a free Team What is Teams? Learn more. Why is boron trifluoride a lewis acid? Ask Question. Asked 6 years, 1 month ago. Active 4 years, 3 months ago. BF 3 is a Lewis acid, but note it has no H to donate, it represents a new class of acids. Lewis acids, substances like BF 3 , or AlCl 3 compounds of periodic table group III atoms , have only 6 electrons in their bonding orbitals and therefore have available empty , energetically accessible, orbitals that are available to accept an electron pair from the Lewis base the electron pair donor.

All of these elements play a critical role in biological systems through their behavior as Lewis acids. An important example is the heme group of hemoglobin. In the center of this group is a positively charged iron Fe atom. Such positively charged ions cations have empty orbitals that can interact with the lone pair electrons from Lewis bases and form Lewis acid-base complexes.

In the case of hemoglobin, important Lewis bases are O 2 and CO 2 and CO , and it is this interaction that is involved for moving oxygen into the body from the lungs and from CO 2 from the body to the lungs.