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35.2: Introduction

  • Page ID
    29319
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    Radioactive decay is the process of an atom changing into a different type of atom; it is a change in the number of protons.  Half-life is the time it takes for one half of a sample of radioactive atoms to decay, so that half of the original number of atoms have decayed.  Each radioactive isotope has its own half-life.  The half-life of an isotope of carbon may be used to determine the age of a fossil.  The amount of a radioactive isotope remaining in a sample indicates the approximate age of the sample. 

    Table \(\PageIndex{1}\): Radioactive Isotope and Half-life

    Radioactive Isotope

    Half-life

    \(\ce{_{94}^{239}Pu}\)

    24,400 years

    \(\ce{_{92}^{238}U}\)

    4.51 x 109 years

    \(\ce{_{84}^{214}Po}\)

    0.00016 seconds

    \(\ce{_{83}^{210}Bi}\)

    5 days

    \(\ce{_{82}^{210}Pb}\)

    20.4 years

    \(\ce{_{6}^{14}C}\)

    5,730 years

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    35.2: Introduction is shared under a CC BY license and was authored, remixed, and/or curated by LibreTexts.

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