clei (in a bond involving two atoms)
and there are corresponding molecular orbitals for electrons (see illustration). It is convenient in considering
these to regard them as formed by
overlap of atomic orbitals. In a hydrogen molecule the s-orbitals on the
two atoms overlap and form a molecular orbital between the two nuclei. This is an example of a sigma orbital. In a double bond, as in ethene,
one bond is produced by overlap
along the line of axes to form a
sigma orbital. The other is produced
by sideways overlap of the lobes of
the p-orbitals (see illustration). The
387
orbital
o
x
y
z
symmetrical
s-orbital
x
y
z
z
x
y
p y
p z
p x
y
x
z
three equivalent p-orbitals, each having 2 lobes
Atomic orbitals
p-orbitals
H
H
H
H
C
C
pi orbital
H
H
C
C
H
H
sigma orbital
hybrid sp 3 -orbitals
Molecular orbitals: formation of the double bond in ethene
Orbital
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