I know all about the types of reactions, synthesis, decomp. etc., but when a bond is broken, how do you know that the free element will bond to another molecule?
Is it because that element has a higher electronegativity? Is it because the product is lower energy?
Why does the free element choose a specific element to bond and how do I know what element it'll bond with?
Why does the free element choose a specific element to bond and how do I know what element it'll bond with?
Science has more answers related to "how" rather than "why"? Can we answer why do you have five fingers and two eyes? Not as yet, but scientists can talk a little bit how the eye works.
Similarly, your open ended query depends on what is meant by "bond"? These are perhaps the mysterious forces of nature. Conventional textbooks teach that noble gases are nonreactive with a few exceptions, but someone who is doing microwave spectroscopy knows that Argon gas forms "clusters" with many many organic molecules in the gas phase i.e., this gas is too reactive for a spectroscopist who is interested in studying the behavior of single organic molecules.
To add an analogy: imagine you have a friend who married a jerk, and you wonder why. After all, there are so many people in the world, nearly $10^{10}$ at the latest count! How do people decide who to pair up with? Well, in that case it might have been due to a chance encounter at a mixer at which both got slightly tipsy (and believe it or not he happened to be the nicest guy there).
The analogy is that atoms don't choose. They usually just mix randomly, sometimes slowly, sometimes at extremely high speeds. There is sometimes no chance to evaluate all possible matches, it's the first atom you encounter you end up with. At times that one is a rare catch, other times it's one like any other. And sometimes an atom dumps a weakly-bound jerk when it later meets another more attractive atom.
