sentence: Atoms are the most simple blocks that make up matter.
sentences_before: Demonstration of the nuclear fuel cycle.'Nuclear energy' is the energy that holds together the nucleii of atoms.
sentences_after: Every atom has in its center a very small nucleus. Normally, nuclear energy is hidden inside the atoms. However, some atoms are radioactive and send off part of their nuclear energy as radiation. Radiation is given off from the nucleus of unstable isotopes of radioactive substances.
concept_name: atom
headings: Nuclear energy
categories: Nuclear energy