The term for the potential energy stored in the nucleus of an atom is nuclear energy. This energy is released during nuclear reactions, such as fission (splitting heavy nuclei) and fusion (combining light nuclei). In fission, atoms like uranium-235 release a significant amount of energy when their nucleus splits. In fusion, energy is produced when hydrogen nuclei combine to form helium, as seen in stars. Harnessing nuclear energy offers both opportunities and challenges in energy production, highlighting its potential for renewable energy and concerns regarding safety and waste management.