I'm reading an online biochemistry textbook for fun (yes, I'm a nerd), and a question that has bothered me on chemistry before popped up again. The question here is not specific for the chemical process described, but I needed an example:

By adding energy to a molecule of formic acid (CH2O2), it kicks out an O and becomes formaldehyde (CH2O). More energy makes it methanol (CH3OH), and more energy makes that methane (CH4).

I get that energy allows the molecule to become a different molecule of a higher energy state; it essentially stores the energy as new or altered chemical bonds. What I never understood is why? It is natural for the molecule to try to go to a lower energy state, releasing energy in the bonds, as it does under oxidation/"burning". So why doesn't it just immediately release the added energy, rather than store it in bonds? What prevents the formaldehyde from saying "I see your energy, but I'll just do what's easier for me and release some of my own, and become fromic acid"? After all, no matter how much energy I use to blast a block of stone into the air, it's going to fall down again, unless someone up there catches it. What's "catching" the higher-energy molecule and preventing it from "falling back" into the more stable, lower-energy molecule?

The answer seems like it might be leaning on atomic theory more than chemistry, but I thaught I'd give it a shot here...

Thanks in advance.

I'm reading an online biochemistry textbook for fun, and a question that has bothered me on chemistry before popped up again. The question here is not specific for the chemical process described, but I needed an example:

By adding energy to a molecule of formic acid ($\ce{CH2O2}$), it kicks out an O and becomes formaldehyde ($\ce{CH2O}$). More energy makes it methanol ($\ce{CH3OH}$), and more energy makes that methane ($\ce{CH4}$).

I get that energy allows the molecule to become a different molecule of a higher energy state; it essentially stores the energy as new or altered chemical bonds. What I never understood is why? It is natural for the molecule to try to go to a lower energy state, releasing energy in the bonds, as it does under oxidation/"burning". So why doesn't it just immediately release the added energy, rather than store it in bonds? 

What prevents the formaldehyde from saying "I see your energy, but I'll just do what's easier for me and release some of my own, and become formic acid"? After all, no matter how much energy I use to blast a block of stone into the air, it's going to fall down again, unless someone up there catches it. What's "catching" the higher-energy molecule and preventing it from "falling back" into the more stable, lower-energy molecule?

The answer seems like it might be leaning on atomic theory more than chemistry, but I thought I'd give it a shot here.