6.4.2.3 Half-lives and the Random Nature of Radioactive Decay Flashcards
1
Q
What does radioactive decay being random mean?
A
- can’t predict which nucleus in a sample will decay/when any of them will
2
Q
What is the half-life of a radioactive isotope?
A
- time it takes for number of nuclei of isotope in a sample to halve
- time it takes for count rate (or activity) from a sample containing isotope to fall to half its initial level
3
Q
What does a short half-life mean?
A
- activity falls quickly because nuclei are very unstable and rapidly decay
4
Q
Why are sources with a short half-life dangerous?
A
- high amount of radiation they emit at the start
- become safe quickly
5
Q
What does a long half-life mean?
A
- activity falls more slowly because most nuclei don’t decay for a long time
6
Q
Why are sources with a long half-life dangerous?
A
- nearby areas exposed to the source will be for (millions of) years
7
Q
What is the equation for net decline?
A
- net decline = (initial number -number after X half-lives)/initial number
