Half-Life Period (T1/2 or t1/2):

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The half-life period of a radioelement is defined, as the time required by a given amount of the element to decay to one-half of its initial value.

t1/2 = 0.693/λ

Now since l is a constant, we can conclude that half-life period of a particular radioelement is independent of the amount of the radioelement. In other words, whatever might be the amount of the radioactive element present at a time, it will always decompose to its half at the end of one half-life period.

Let the initial amount of a radioactive substance be No


Amount of radioactive substance left after n half-life periods

N = (1/2)n N0

Total time T = n x t/12 where n is a whole number.
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