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COSMOS · NUCLEI · TIME
Distinguish cosmic production, isotope identity and the limits of a radioactive clock.
FOLLOW A QUESTION
Proton number identifies an element. Isotopes of that element have different neutron numbers. Carbon-12 has six protons and six neutrons; carbon-13 has six protons and seven neutrons.
In a chemical change, changing bonds while holding both nuclear counts fixed leaves isotope identity unchanged. Carbon-12 and carbon-14 also show that one element can have stable and radioactive isotopes.
MAKE THE CONNECTION
Two modeled carbon atoms each have six protons. One has six neutrons; the other has seven. What differs?
Explore the model (optional)
Count protons to identify the element, then include neutrons to obtain the mass number.
Arbitrary nucleon count markers, not nuclear shape, size, internal positions or a binding-energy calculation. Electrons are omitted. The separate decay model describes a hypothetical isotope, not the selected real nuclide.