Question
On the basis of hybridisation, discuss the orbital structure of: (i) BeF2 (ii) BH3.
Solution
(i) Orbital structure of BeF2 :
To form BeF2 molecule, an electron gets promoted from filled 2s orbital to vacant 2p orbital. Therefore, the excited configuration of Be atom is
In BeF2, Be atom is sp hybridised i.e. two hybrid orbitals are directed along a straight line with a bond angle equal to 180°. Each sp hybrid orbital overlaps axially with 2p half-filled orbital of F atom to form sigma Be – F bonds.
(ii) Orbital structure of BH3:
The electronic configuration of B (Z = 5) is 1s2 2s22P1.
In BH3, B atom is sp2 hybridised and the three hybrid orbitals overlap axially with the orbital of the hydrogen atom to from three sigma B–H bonds.
The shape is trigonal planar.
To form BeF2 molecule, an electron gets promoted from filled 2s orbital to vacant 2p orbital. Therefore, the excited configuration of Be atom is
In BeF2, Be atom is sp hybridised i.e. two hybrid orbitals are directed along a straight line with a bond angle equal to 180°. Each sp hybrid orbital overlaps axially with 2p half-filled orbital of F atom to form sigma Be – F bonds.
(ii) Orbital structure of BH3:
The electronic configuration of B (Z = 5) is 1s2 2s22P1.
In BH3, B atom is sp2 hybridised and the three hybrid orbitals overlap axially with the orbital of the hydrogen atom to from three sigma B–H bonds.
The shape is trigonal planar.
