Question

Arrange the following as indicated:
$P{F_3}$, $PC{l_3}$, $PB{r_3}$, $P{I_3}$ (Decreasing Lewis acid strength)

Answer 1

Hint: We know that Lewis acids and bases are depicted by the Lewis hypothesis of acid base responses as electron-pair acceptors and electron pair benefactors individually. In this way, a Lewis base can give a couple of electrons to a Lewis acid to frame a product containing an organized covalent bond. This product is likewise alluded to as a Lewis adduct.

Complete answer:
We must have to remember that the Lewis Acids are the substance species which have void orbitals and can acknowledge electron sets from Lewis bases. This term was traditionally used to depict compound species with a three-sided planar construction and a vacant p-orbital. An illustration of such a Lewis corrosive would be \[B{R_3}\] (where R can be a halide or a natural substituent).Water and some different mixtures are considered as both Lewis acids and bases since they can acknowledge and give electron sets dependent on the response.
Instances of Lewis Acids:
Some basic instances of Lewis acids which can acknowledge electron sets include:
The hydrogen ion particles (or protons) can be considered as Lewis acids alongside onium particles like \[{H_3}{O^ + }\]
Cations of metals, for example, \[M{g^{2 + }}\] and \[L{i^ + }\] can shape coordination compounds with water going about as the ligand. These aqua edifices can acknowledge electron matches and act as Lewis acids.
Carbocations given by \[{H_3}{C^ + }\] and other three-sided planar species will in general acknowledge electron sets.
The arrangement for the Lewis corrosive strength for:
\[P{F_3} > {\text{ }}PC{l_3} > {\text{ }}PB{r_3} > P{I_3}\]
Since: Lewis acids tend to acknowledge electrons. As referenced above, phosphorus has void d orbital in its valence shell to acknowledge electrons. Additionally, the electronegativity of the halides diminishes as \[F > {\text{ }}Cl > Br > I\]. In this way, fluorine has more grounded proclivity towards electrons making PF3 more grounded Lewis corrosive while making \[P{I_3}\] the most vulnerable Lewis acid.

Note:
Lewis Base: We need to know that the nuclear or atomic compound species having a profoundly limited HOMO go about as Lewis bases. These compound species can give an electron pair to a provided Lewis corrosive to shape an addict, as talked about prior.
The most well-known Lewis bases are smelling salts, alkyl amines, and other ordinary amines. Usually, Lewis bases are anionic in nature and their base strength by and large relies upon the pKa of the relating guardian corrosive. Since Lewis bases are electron-rich species that can give electron-sets, they can be named nucleophiles. Essentially, Lewis acids can be named electrophiles since they carry on as electron-pair acceptors.