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What is the difference between nuclear and atomic?
The atom is the smallest identifiable unit of matter. It has a nucleus which contains one or more protons and then one or more electrons orbiting in outer layers. The word nuclear in the phrase 'nuclear bomb' means 'involving or related to atomic nuclei or an atomic nucleus'. The phrase in that sense can be used interchangeably with 'atomic bomb'. The two terms are synonymous when modifying energy and weapons terms. However, when talking about energy level or physics, nuclear denotes the dynamics of particles in the core of an atom, including the protons and neutrons. When talking about energy level, physics, or chemistry, atomic denotes the configuration of electrons that determines the chemistry of an atom and the dynamics of the particles in the outer layer, the electrons. In describing weapons, though, nuclear is a general term for weapons that release energy from nuclear reactions. Atomic refers to the earliest and least sophisticated weapons, which use nuclear fission. Then there is thermonuclear. Thermonuclear weapons use nuclear fusion, which results when the nuclei of hydrogen isotopes merge and release energy. Fusion takes place only at very high temperatures, so thermonuclear devices first set off a fission reaction, which triggers the fusion; some weapons have two fusion stages, the first initiating the second. In describing physics, atomic physics deals with the properties of atoms, which are mainly due to their electron configuration. Nuclear physics, on the other hand, deals only with nuclei. It studies the structure of nuclei, and their reactions and interactions.