"Units of Unsaturation"

I've just learned to calculate
Something for chem it's really great
When you find a bond of three
Two is what the unit number will be. Mmmmmm.

Look for rings and double bonds
And you'll be moving right along
They are worth one whole unit each
Does anyone want to go to the beach? Dahhhhhhh.

2C + 2 -H / 2 (Two C plus two minus all the hydrogen's divide by two)

Here's some things to keep in mind
You're going to leave the O's behind
H is the same as a halogen
Use a half a carbon for a nitrogen. Mmmmmmm.

2C + 2 -H / 2 (Two C plus two minus all the hydrogen's divide by two)