Mendeleev · science lesson
Half-life: a statistical property
Half-life describes the evolution of a radioactive population. It does not predict the exact decay time of an individual nucleus.
Start with the idea
Half-life describes the evolution of a radioactive population. It does not predict the exact decay time of an individual nucleus.
A concrete example
After three half-lives, the expected remaining fraction is (1/2)³ = 1/8.
Practical method
Go one step deeper
After 1, 2, 3 and 4 half-lives, expected fractions are 1/2, 1/4, 1/8 and 1/16: the evolution is exponential, not linear.
Common trap
A trend or model is not an exceptionless law. Always check the quantity’s definition and the conditions being compared.
Check your understanding
Can you explain the phenomenon in your own words before looking at an equation?