Ø Types
of Overlapping: There are two types of orbital
overlapping.
1. Axial Overlapping or Sigma Bond: This
type of covalent bond is formed by the end to end (hand-on) overlap of bonding
orbitals along the internuclear axis. This is called as head on overlap or
axial overlap. All single bonds are sigma bonds. A sigma bond can be formed by
the following ways:
i)
s-s overlapping: Here the overlapping of two half-filled s-orbitals take place along the inter nuclear axis.
iii)
p-p overlapping:
Here two half-filled p- orbitals of two atoms
overlap.
2. 2. pi(π ) bond: In
the formation of π bond the atomic orbitals overlap in such a way that their
axes remain parallel to each other and perpendicular to the internuclear axis
or bond formed by sidewise overlapping of atomic orbitals called pi bond. The
orbitals formed due to sidewise overlapping consists of two charged clouds
above and below the plane of the participating atoms.
A π bond is always present along with σ bonds. A double bond contains one σ bond and one π bond. A triple bond contains one sigma bond and two pi bonds.
A sigma bond is stronger
than a pi bond. This is because the extent of overlapping is greater in a sigma
bond.
Difference
between Sigma and Pi Bond
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