Question

How do you determine pi and sigma bonds?

Answer 1

A `sigma`-bond is the first bond between two atoms, and a `pi`-bond is any bond in excess to that.

Explanation:

For two atoms to join they have to have at least one bond between them. This is the `sigma` bond.

Any bonds in excess to the `sigma` are called `pi`-bonds. For example, a double bond has one `sigma` and one `pi`, while a triple bond has one `sigma` and two `pi`. Whatever the bond, it can only ever have one `sigma`

On an `n`-bond, where `n` is the number of covalent bonds between two atoms, it is made of

`n -> sigma + (n-1)pi`