# What is meant by the half life of a radioactive nuclide?

##### 1 Answer

Aug 27, 2016

The time in which 50% of the radioactive atoms has decayed.

#### Explanation:

The **half life** of radioactive nuclides is defined as the time in which half of the original number of radioactive atoms has decayed.

Imagine you start with 100 atoms of nuclide X.

X decays to nuclide Y with a half life of 10 days.

After 10 days 50 atoms of X are left, the other 50 have decayed to Y. After 20 days (2 half lifes) only 25 atoms of X are left etc.

For the equation, check this answer on Socratic.