Sigma and pi bond

[sarahtang4B]

Can somebody explain again why a double bond has one sigma and one pi bond and why a triple bond has one sigma and 2 pi bonds?

[Shubham Rai 2C]

The first bond to form is always the sigma bond. There can only be one sigma bond between two atoms and any bonds formed after are the pi bonds due to the way the electrons of each atom interact with each year. Thus, a double bond has one sigma bond and pi bond, while triple bonds are made of one sigma and two pi bonds.