Atoms cannot "die" in the normal sense. However I expect you already knew this but didn't know how to word the question. So, what CAN happen to the atom? The most common thing is that it bonds with another atom, or several, to form a molecule by sharing, borrowing, or giving up electrons. Since electrons are considered part of the atom, it isn't the same as it used to be. We also have nuclear decay, where particles in the nucleus are transformed into other particles, ejected completely out, or the nucleus splits into large pieces, with each piece forming a new atom of a different element. Finally there is nuclear fusion where the nuclei of two atoms fuses together to form another one of a different element.