Where does the energy come from that drives an Atom? This question is probably one of the first things discussed amongst classrooms, etc. Unfortunately I haven't had the opportunity to discuss this topic as much as I wish I had, so far i've heard that we do not know where the energy comes from, or even what is really is (in terms of giving it a texture, if you wish)
Is this correct?
There are several aspects of an answer to your question, so bear with a somewhat long answer.
1. There is no energy required to drive an atom. An atom is not really just like a little solar system, but even with tht analogy no energy is required to maintain the motion. Energy is not required to maintain motion, unless there is a mechanism whereby energy is lost. The reason that your car burns gasoline all of the time is that it must overcome friction and air resistance, and because it goes up and down hills. Those things cause energy to be lost to the car and turned into heat. But think about the solar system and the planets revolving around the sun. They do not receive any additional push to keep them in orbit. They just keep going round and round, but because there is no frictional loss they need no new energy to continue that motion. That is the case with atoms as well. Within an atom there is no frictional loss, and no air resistance so the electrons electrons, proton and neutrons don't need a constant influx of energy to keep on doing what they are doing.
2. Atoms are build of elementary particles, the electrons are elementary. The protons and neutrons are composed of quarks. They are held together by the exchange of other elementary particles that create the forces that hold together the nucleus (weak and strong forces) and attract the electrons to the nucleus (electromagnetic force). All of those particles ARE energy. Whether you look at the theory of relativity or at quantum theories, a critical realization is that Einstein's equation E=mc^2 applies and tells us that matter and energy are really the same thing. So not only does the atom not require new energy to "keep functioning", it actually is itself just a form of energy. At the deepest level there is no difference between matter and energy.
3. Matter can be realized as energy. That is precisely what happens in a nuclear generating plant or a nuclear bonb. A little bit of the matter in the atom is released in the form of photons and heat when a large nucleus is split into a small one or when two light nucleii combine to form a larger one. There is no net gain or loss, just a change the form of the energy that was always there in the form of energy.
4. Energy can be transformed into matter. If you have two photons (light energy) that are of sufficient energy (high frequency) it is possible for them to interact and to form a particle of conventional mass. That is what is believed to have happened during the Big Bang. It also happens when light is shown on a material to heat it up. A photon hits an atom and is absorbed, which means that it provides its energy to an electron, the electron goes to a higher energy state within the atom, and that atom gains just a little bit of mass -- the mass associated with the energy of the photon which also obeys the equatin E=mc^2 (in the case of the photon the energy term E is also associated with the color of the light via E=hf where h is Planck's constant and f is the frequence of the light).
5. So basically the unverse is nothing but a big gob of energy. Some of it is in the form of ordinary matter, some of it is in the form of what is typically "energy" but it is all energy of one form or another. There seem to be some other categories that we don't understand very well yet, dark energy and dark matter, but they are still just types of energy. It is all energy, energy all the way down (turtles are energy too). So far as we know the energy content of the complete universe doesn't change, energy just changes form like a chameleon, but the total amount remains constant.
6. Your final question was something on the order of "Where does all this energy come from?". Well, it seems that the energy of the universe has been the same ever since the universe began. So, following that beginning there is no need for energy to come from anywhere. I is just here, doesn't change in quantity, but just keeps changing its shape. As to where the universe came from, that is indeed a mystery. We have some pretty good theoretical descriptions of how things worked immediately following (well a couple of billionths of a second after) the Big Bang itself. From that point on, our descriptions of the physical laws that govern everything are pretty good -- still not perfect and still being studied and improved, but pretty good. We have no idea of why the Big Bang occurred. In fact, since it appears that all space, all matter, all energy, and tme itself began with the Big Bang, physics cannot even begin to address that question, because physics itself began with the Big Bang.
Just like the rest of the universe, the energy necessary for an atom to function is in place inside the atom already, and it just keeps on humming, no additional fuel is necessary.