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| physical object > natural object > particle > charged particle > nucleus > isotope |
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| isotope comparison table | ||
| Subject | has definition | is a kind of |
|---|---|---|
| nucleus | The massive, positively charged central part of an atom, composed mainly of protons and neutrons, around which the electrons revolve. The radius of an atomic nucleus is directly proportional to the cube root of its mass. Density at least 1014 g cm-3. Radius 10-12-10-13 cm. | charged particle |
| isotope | Two nuclei with the same number of protons but different numbers of neutrons are said to represent the same element, but different isotopes. For example, helium-3, with two protons and one neutron in each nucleus, and helium-4, with two protons and two neutrons, are two different isotopes of helium. For another example, see deuterium. | nucleus |