Why is nf3 not a lewis base

A Lewis acid is a substance that accepts a pair of electrons to form a covalent bond. A Lewis base is a substance that donates a pair of electrons to form a covalent bond. So, a Lewis acid-base reaction is represented by the transfer of a pair of electrons from a base to an acid. A hydrogen ion, which lacks any electrons, accepts a pair of electrons. Ammonia consists of a nitrogen atom as the central atom with a lone pair of electrons.

The reaction between ammonia and the hydrogen ion can be depicted as shown in the Figure 1. Some reactions that do not qualify as acid-base reactions under the other definitions do so under only the Lewis definition. An example is the reaction of ammonia with boron trifluoride. Boron trifluoride is the Lewis acid, while ammonia is again the Lewis base.

As there is no hydrogen ion involved in this reaction, it qualifies as an acid-base reaction only under the Lewis definition. The Table below summarizes the three acid-base theories. Do the practice problems associated with Section 3 Lewis Theory at the link below:.

Skip to main content. Acids and Bases. Search for:. I know Lewis acids act as an electron pair acceptor and a Lewis base as an electron pair donor. But this is where my knowledge becomes a little sketchy, and hence my question:.

When considering group 15, is it possible for the elements of this group to form compounds which are either Lewis acids or bases? Firstly, the requirements for Lewis acids of group 15, is it empty d-orbitals or an incomplete octet which give a compound the ability to accept two electrons?

Then are the requirements for something to be a Lewis base purely the presence of two non bonding electrons? I am a little lost, would like to know if the above is along the right lines. Do things like electronegativity and atom size play a part? I think this is a base? I think this is an acid? For anyone else with a similar question above I have been researching this for the last day or two, I have found Group 15 should be spilt into two groups - either nitrogen or heavier G15 elements when considering basicity or acidity.

These compounds are generally only weak bases. In my research I have found the greater the electronegativity of the lone pair atom in comparison to its ligands i. The more free the lone pair is the stronger the base is, hence NI3 is the strongest base out of the trihalides. This is why NH3 is such a great base as the lone pair on N is not inductively pulled towards the ligands because H is relatively less electronegative.

Whereas in NF3 the lone pair is so drawn away from nitrogen this compound is sometimes not even classed as a base, hence it is the weakest of the trihalides. The reason nitrogen is on its own is because it has max coordination number 4.

I have found halides, either tri or penta, are generally classed as Lewis acids. First the trihalides, these act as mild Lewis acids towards trialkylamines and halides. This is even though the P, As or Sb will have a lone pair. As before, this is partly due to electronegativity reducing the availability of the lone pair. My textbook points out PF3 is probably a little bit unusual in this group because it has empty d-orbitals making it a weak sigma donor yet a strong pi acceptor.

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. Group