Radioactivity

Radioactive decayUnstabe nuclei will try to achieve stability either by emitting α, ß and/or γ particles to remove excess proton or neutrons.The rate of decay is proportional to the number of radioactive nuclei there are.The number of radioactive nuclei at time, t is given by

where   is the number of radioactive nuclei at t = 0and λ is the radioactive constant.The time taken for the sample to halve it's number of radioactive nuclei / or to halve its activity is called half- life ,

where

Example :

The half-life of a particular radioactive nuclide is such that 3/8 of a sample becomes stable in 12 days. What is the fraction that remains radioactive after 24 days?

1. Express the decay constant

In the first condition, 3/8 are stable i.e 5/8 of the initial number of nuclei are radioactive

2. The fraction that is still radioactive

x = 4/5