Question

BF3 is a planer and electron deficient compound. Hybridization and number of electrons around the central atom, respectively are:

1. sp3 & 4
2. sp3 & 6
3. sp2 & 6
4. sp2 & 8

(neet 2021)​

Answer 1

Answer:

For Hybridization:

Steric number=½(v+x-c+A)

V=valence electron of central atom

X=number of monovalent atom

C=number of cation

A=number of anion

So the central atom is B

Then,steric number=½(3+3-0+0)=½×6=3=sp² hybd"

Geometry=Trigonal planar

As there is 3 F so there is 3 bonds, so electron around central atom is 6.

So option 3 is the correct answer.

Answer 2

Given info : BF₃ is a planar and electron deficient compound.

To find  : Hybridization and the number of electrons around the central atom, respectively are..

solution : first write no of valence electrons of each element.

for Boron , no of valence electrons = 3

for Fluorine, no of valence electrons = 7

now sum of total no of valence electrons = 1 × valence electrons in B + 3 × valence electrons in F

= 1 × 3 + 7 × 3 = 24

no of bond pairs = no of elements in compound - 1 = 4 - 1 = 3

no of lone pairs = ( total no of valence electrons - no of bond pairs × 8)/2

⇒ no of lone pairs = (24 - 3 × 8)/2 = 0

so total no of pairs = lone pairs + bond pairs = 0 + 3 = 3 ( ∴ sp²)

therefore the hybridization of the compound is sp² ( triangular planar)

now the number of electrons around the central atoms = bond pairs × 2

= 6 [ you can understand to see the diagram of the compound ]

therefore the hybridisation and the number of electrons around the central atom sp² and 6 respectively.