Explore the Radioactive Decay & Half-Life Simulator
Watch hundreds of unstable atoms decay at random and compare the count with the half-life curve. Free, no signup, runs in your browser.
- Free to use
- No signup
- Nothing to install
- Runs in your browser
Illustration. Open the tool for the real thing.
See it in action
The Radioactive Decay & Half-Life Simulator with sample data entered and the result showing.
What is the Radioactive Decay & Half-Life Simulator?
Watch hundreds of unstable atoms decay at random and compare the count with the half-life curve. It runs in your browser, so a change to a setting or a drag on an object shows up at once.
Carbon dating, medical imaging and cancer treatment, smoke detectors, nuclear power and dating rocks all use radioactive decay.
3 steps to your result
Open the tool and follow along. Nothing to install.
What you get
Each atom decays at random, but a large group decays predictably.
After one half-life half of the atoms are left, after two a quarter, and so on.
The half-life does not depend on how many atoms you have.
Press Start and check the atoms left at 1, 2 and 3 half-lives.
Use only 50 atoms and see how noisy the graph is.
Use 600 atoms and compare with the theory line.
Used for
Pick one to see how it fits.
Atomic & Quantum learners
Advanced high-school and university students in chemistry and physics, and curious learners who want to see how the atomic world behaves.
Try it freeTeachers
For teachers: project the Radioactive Decay & Half-Life Simulator on the board, let students predict the result, then run it together and test this: Use only 50 atoms and see how noisy the graph is. For students: change one thing at a time and write down what changes.
Try it freeHow it compares
A plain look at this tool next to the usual alternative.
| This simulation | Textbook diagram | |
|---|---|---|
| Interactive | Drag, tap and change settings | Fixed picture |
| Install | Nothing to install | Not needed |
| Cost | Free to use | Depends on the book |
Questions people ask
What is a half-life?
The time it takes for half of a sample of unstable atoms to decay. It is a fixed property of each isotope.
Can you predict when one atom will decay?
No. Each atom decays at random. Only the behaviour of a large group is predictable.
Is the Radioactive Decay & Half-Life Simulator free to use?
Yes. The Radioactive Decay & Half-Life Simulator is free, needs no signup or download and runs in your web browser. It is part of the Atomic & Quantum group of AZRS simulations.
Does the Radioactive Decay & Half-Life Simulator work on a phone or tablet?
Yes. The Radioactive Decay & Half-Life Simulator takes touch input as well as mouse input, so you can use its 3 adjustable settings with a finger. A larger screen makes the controls and graphs easier to read.
How do I use the Radioactive Decay & Half-Life Simulator?
1. In the Radioactive Decay & Half-Life Simulator, use the controls to change Half-life, Number of atoms, Samples. The simulation reacts instantly. 2. In the Radioactive Decay & Half-Life Simulator, pick an option such as Custom, Fast (Ba-137m), Slow (long-lived) to switch modes or load an example. 3. In the Radioactive Decay & Half-Life Simulator, press "Start", "Reset atoms" to start, reset or change what is happening. 4. Start with this experiment: Press Start and check the atoms left at 1, 2 and 3 half-lives. Drag any glowing handle, object or slider with your mouse or finger and the Radioactive Decay & Half-Life Simulator responds in real time. 5. Change one setting at a time and watch which readout moves, then compare it with this idea: Each atom decays at random, but a large group decays predictably.
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Try the Radioactive Decay & Half-Life Simulator now
Watch hundreds of unstable atoms decay at random and compare the count with the half-life. Free to use.
Try it free