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Periodic table · chemistry · physics
Science connections

Nucleus To Radioactivity

Radioactivity comes from unstable atomic nuclei that transform spontaneously and emit radiation. It is a nuclear phenomenon, distinct from ordinary chemical reactions involving electrons. The same phenomenon helps us understand nuclei, date materials and build important medical techniques. Half-life is the time required for the expected number of undecayed nuclei, or equivalently the activity of a large sample, to fall to one half of its initial value. Successive half-lives produce halves, quarters, eighths and so on; the process is exponential rather than linear. Binding energy is the energy

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Radioactivity comes from unstable atomic nuclei that transform spontaneously and emit radiation. It is a nuclear phenomenon, distinct from ordinary chemical reactions involving electrons. The same phenomenon helps us understand nuclei, date materials and build important medical techniques. Half-life is the time required for the expected number of undecayed nuclei, or equivalently the activity of a large sample, to fall to one half of its initial value. Successive half-lives produce halves, quarters, eighths and so on; the process is exponential rather than linear. Binding energy is the energy required to separate a nucleus into its constituent nucleons. It is related to the nucleus’s mass defect through E = Δmc². Binding energy per nucleon helps explain why both fusion of light nuclei and fission of very heavy nuclei can release energy.

Primary references

IUPAC Gold Book · NIST · BIPM