[HHzygi]

I am familiar with the octet rule, but what is confusing me is sometimes, especially in linear bonds, there is 2 single bonds with 2 lone pairs around the central atom.  And other times a different linear molecule is drawn with two double bonds to satisfy octet instead of the two lone pairs around the central atom.

So what really dictates if the central atom will form two double bonds or will just have two single bonds and 2 lone pairs?

[zhyx00]

would you please illustrate your question with a picture? I am in terested in it.

[stewie griffin]

There's not necessarily an easy rule that tells you from the start that the you need double bonds... though as you get used to doing more and more lewis structures you kinda get to know when you'll need more than just a single bond.
What dictates whether or not the central atom will have a single or double (or even triple) bond is the octet rule. Here's the process I use to get the job done...
I always just start with single bonds to the central atom, and then distribute the rest of the electrons available around the other atoms to try to satisfy every atom's octet. If you find that once you're out of electrons that the central atom still doesn't have it's octet fullfilled, you're gonna have to start over by making a double bond to the central atom. Then repeat the process of distributing electrons to the others. Sometimes you may have to do this entire process more than once (for example in N₂ there's a triple bond, in CO₂ each oxygen has a double bond to the central carbon).