Well for most purposes it’s OK to talk about the law of the “conservation of energy”, which states that energy isn’t created or destroyed, it just changes forms.
However for this type of question we need to think about the “conservation of mass-energy”, since Einsteins theory of “special relativity” showed that mass and energy are equivalent.
So it is possible to convert mass to energy and back again. The two are related through the famous equation e=mc^2 (energy = mass x speed of light squared).
This isn’t important in most situations as mass doesn’t change. But where atoms start getting split then it needs to be taken into account. This is how nuclear reactors and atomic bombs are able to produce such large amounts of energy, by converting mass.
Thankfully for the sort of stuff that I research I can safely assume that energy is conserved because mass is also conserved. If I worked in the nuclear industry, or looked at some really hardcore physics, then maybe I would have to take mass-energy equivalence into account!
Atoms can be made or destroyed through fusion/fission.
Fusion: atoms with lower molecular numbers can be combined together to make an atom of a higher molecular number. This is what happens in stars – hydrogen is fused into helium.
Nuclear fission: atoms with a high molecular number, loose neutrons and protons to become an atoms with a lower molecular number. We call this process radioactive. A natural process would be uranium turning into lead.
Atomic bombs: fission takes place in a chain reaction where all the energy is released very very very very quickly, creating a massive explosion.
Nuclear bomb: an atom bomb explodes with nuclear fission and triggers hydrogen atoms fusing into helium atoms in the next step.
Overall… YES! Atoms can be made and destroyed, releasing massive amounts of energy!