The concerpt of half-life
When one radioactive
element is transmuted into another, this always occurs at a constant rate
which is independent of the orginal quantity of this substance. It is
therefore convinient to have a scale by which the rate of radioactive decay
can be indecated. Such a scale is called the half-life of the substance, and
represents the time taken for the intensity of the rays to be produced to
half their original value, i.e for half active parent atoms to disintegrate
into atoms of the doughter elements.
Half-lives vary between fractions of a second and 1 000 000 000 000 000 000
years!
| Radioactive isotope | Half-life |
| Boron | 0,000 000 000 000 000 000 8s |
| Carbon | 5 730a |
| Uranium | 0,00000000451a |
| Radon | 3,82 d |
| Polonium | 0,0000003s |
| Bismuth | 19,7 min |
| Arsenic | 26,5h |
| Radium | 1 622a |
| Cobalt | 5,27a |
key
s = seconds; min = minutes; h = hours; d = days; a = years
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