Transcript Sigma and Pi Bonds

Title: Lesson 10 Sigma and Pi Bonds
Learning Objectives:
– Understand and identify pi and sigma bonds
– Meet molecular orbital theory and attempt some simple
molecular orbital diagrams
Shapes of Orbitals Recap Video - Funny
Sigma-bonds/ -bonds

-bonds are formed when two orbitals from neighbouring atoms overlap along the axis of
approach

This type of bond forms by the overlap of s orbitals, p orbitals and a hybrid of s and p
orbitals.

It is the bond that forms a SINGLE covalent bond

Electron density is concentrated between the nuclei of the bonded atoms
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Pi-bonds/ -bonds

-bonds are formed when two
orbitals from neighbouring atoms
overlap perpendicular to the axis of
approach

This type of bond only forms by the
overlap of p orbitals alongside the
formation of a sigma bond.

Only occurs in double or triple
bonds

-bonds are weaker than -bonds
(electron density is further from the
nucleus)

Electron density is above and below
the bond axis
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Combination of atomic orbitals giving rise
to each type of bond is summarised below:
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Counting Bonds

For each of the following, determine the number of pi and
sigma bonds:
1.
H2
1.
N2
2.
CH4
2.
C2H4
3.
O2
3.
C3H8
4.
H2O
4.
C3H6
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