The half-life of a radioactive species is the amount of time it takes the quantity of the species to decrease by half. After one half-life, ½ of the initial quantity of material will remain, after two ¼ will remain, after three 1/8 will remain, and so on. Half-lives of radioactive nuclei vary widely, and we’ll list just a few values below to give an idea of the range of timescales covered.
Radioactive Nucleus |
Half-Life |
Carbon-14 |
5,730 years |
Lead-210 |
22.3 years |
Mercury-203 |
46.6 days |
Lead-214 |
26.8 minutes |
Nitrogen-16 |
7.13 seconds |
Polonium-213 |
0.000305 seconds |