(Polar molecules, Non-polar molecules, etc.)
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I'm sure Dr.Lavelle has gone over this in one of his lectures, but I'm still confused about when to use a single/double/triple bond and when to just leave it as a lone pair. I realize that there are thousands of compounds with a lot of exceptions but what is the general rule to look out for when drawing out compounds?
There are a lot of exceptions and ways to draw Lewis structures (hence resonance structures) but I think generally you should try to make bonds over leaving electrons as lone pairs. I believe this tends to make the structure more stable depending on the element and its formal charge. Most of the time you should be able to figure it out from the number of valence electrons.
A good guiding principle is to find formal charge. For example, if nitrogen is double bonded with two lone pairs (satisfying the octet rule), then the formal charge is -1. Whereas, if nitrogen is triple bonded with one lone pair, the formal charge would be zero.
The first thing I would look at when deciding is the formal charge of the individual elements. If the charge is closer to neutral with more bonds that would be the solution as opposed to using lone pair electrons.
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