Behavior of pi bonds

[Spencer T]

When determining the number of pi bonds on question 15 of the Molecular Shape assignment, why does the triple bond contain 2 pi bonds, while the double bond only contains one pi bond? Is there a reason the triple bond contains 2 pi bonds instead of just one bond?

Thanks for the help.

[Patrick Blankenberg]

This is because a single bond is always a sigma bond. This is because when you think of the p-orbitals, only one orbital can overlap, as the other orbitals will be out of phase. These other orbitals lining up side by side make these pi bonds.

For simplicity,

Single bond --> always 1 sigma bond
Double bond --> 1 sigma bond + 1 pi bond (i believe there may be an exception of two but idk if thats in the scope of this class)
Triple bond --> 1 sigma bond + 2 pi bond