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Secondary IV • 1yr.

Hi, I don't understand half life ???

Chemistry
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  • Explanation from Alloprof

    Explanation from Alloprof

    This Explanation was submitted by a member of the Alloprof team.

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    Team Alloprof • 1yr.

    Thanks for your question!

    Half-life is the length of time it takes for half of the atoms of a certain radioactive substance to decay into one or more more stable atoms. This decay emits other particles and energy.

    You can never predict when a radioactive atom will decay. On the other hand, one can take the average time that the atoms of a certain element take to decay, allowing to calculate the half-lives of various radioactive elements.

    Please note: substances do not completely disintegrate after two half-lives. In fact, one can perceive this degradation as a “division by two”. For example, if at the start there were 16 atoms, after a half-life, 8 (16 ÷ 2) will remain. After another half-life, there will be 4 (8 ÷ 2) left. After another half-life, 2 will remain (4 ÷ 2) and so on.

    The concept of half-life is very important in several sciences such as archeology, geology and paleontology since it allows us to estimate the age of artefacts, rocks and fossils. By knowing the initial amount of a certain radioactive substance and comparing it to the amount currently present in an object, one can find its age. This technique is called radiometric dating.

    Do not hesitate if you have other questions!