Is SO3 an acid or base

Lewis's acid-base concept

Even Brönstedt's definition was unable to explain all of the observations. For example, substances such as SO3, BF3 and AlCl3 show at Dissolving in water an acidic reaction even though they are not hydrogen containing compounds. According to Brönstedt, aprotic systems have not yet been covered either. For this reason Lewis (1923, 1938) created a new acid-base concept in which the electronic configuration of the particles came to the fore as a constitutional feature. The definitions are then as follows:
Lewis acids are molecules or ions with an incompletely occupied outer electron shell (particles with an electron gap) that can act as an electron pair acceptor towards other particles by forming a covalent bond.
Lewis bases are molecules or ions with a free electron pair that can be used to form a covalent bond (electron pair donors).
With the acid-base definition according to Lewis it is now z. B. also possible to understand complex formation reactions as acid-base reactions.
Furthermore, a separation from the protic acids is carried out by the definition according to Lewis, i. H. A large number of compounds can react as Lewis acids.
According to the Lewis definition, the Brönsted protic acids are not acids. However, if the proton is regarded as a Lewis acid, the formation of a Brönsted acid is a Lewis acid-base reaction. React as Lewis bases (which are also Brönstedt bases at the same time):
* Molecules with occupied orbitals that are not claimed in an atomic bond.
* Anions as complex ligands.
* Molecules with polar multiple bonds in which the negated atom is the carrier of the basic properties. Advantages of the Lewis acid-base concept:
* The constitutional feature of Lewis acids and bases is their electronic configuration.
* Complex formation is described as a neutralization process!
* Strength extension of the acid term
Disadvantages of the Lewis definition:
* Brönstedt acids have a special position
* Hardly suitable for a quantitative description of the relative strength of an acid or base. This also means that no quantitative description of acid-base equilibria is possible.