Free Atomic & Quantum Simulation

Explore the Build a Nucleus: Protons, Neutrons & Stability

Drag protons and neutrons to build atoms from hydrogen to calcium and check isotopes and stability. Free, no signup, runs in your browser.

Try it free See how it works

Free to use
No signup
Nothing to install
Runs in your browser

Free to use

No signup

Build a Nucleus: Protons, Neutrons & Stability

Setting

Open the Build a Nucleus: Protons, Neutrons & Stability

Illustration. Open the tool for the real thing.

See it in action

The Build a Nucleus: Protons, Neutrons & Stability with sample data entered and the result showing.

Screenshot of the Build a Nucleus: Protons, Neutrons & Stability with sample data entered: The Build a Nucleus: Protons, Neutrons & Stability with sample data entered and the result showing. — Sample data entered into the Build a Nucleus: Protons, Neutrons & Stability. Open the tool to try your own.

Explained

What is the Build a Nucleus: Protons, Neutrons & Stability?

Drag protons and neutrons to build atoms from hydrogen to calcium and check isotopes and stability. It runs in your browser, so a change to a setting or a drag on an object shows up at once.

Isotopes are used in carbon dating, medical imaging, cancer treatment and nuclear power.

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Key idea 1Key idea 2Key idea 3

3 steps to your result

Open the tool and follow along. Nothing to install.

In the Build a Nucleus: Protons, Neutrons & Stability, press "+ Proton", "+ Neutron", "− Proton", "− Neutron" to start, reset or change what is happening.

Start with this experiment: Build carbon-12 and carbon-14. Drag any glowing handle, object or slider with your mouse or finger and the Build a Nucleus: Protons, Neutrons & Stability responds in real time.

Change one setting at a time and watch which readout moves, then compare it with this idea: The number of protons defines the element.

What you get

Key idea 1

The number of protons defines the element.

Key idea 2

Mass number = protons + neutrons.

Key idea 3

Isotopes have the same protons but different neutrons.

Experiment 1

Build carbon-12 and carbon-14.

Experiment 2

Build helium-3 and helium-4.

Experiment 3

Make an unstable nucleus and press Let it decay.

Used for

Pick one to see how it fits.

Use case

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.

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How 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 an isotope?

An atom of the same element with a different number of neutrons.

What is beta decay?

A neutron changes into a proton (or the reverse), emitting an electron or positron.

Is the Build a Nucleus: Protons, Neutrons & Stability free to use?

Yes. The Build a Nucleus: Protons, Neutrons & Stability 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 Build a Nucleus: Protons, Neutrons & Stability work on a phone or tablet?

Yes. The Build a Nucleus: Protons, Neutrons & Stability takes touch input as well as mouse input, so you can drag its objects with a finger. A larger screen makes the controls and graphs easier to read.

How do I use the Build a Nucleus: Protons, Neutrons & Stability?

1. In the Build a Nucleus: Protons, Neutrons & Stability, press "+ Proton", "+ Neutron", "− Proton", "− Neutron" to start, reset or change what is happening. 2. Start with this experiment: Build carbon-12 and carbon-14. Drag any glowing handle, object or slider with your mouse or finger and the Build a Nucleus: Protons, Neutrons & Stability responds in real time. 3. Change one setting at a time and watch which readout moves, then compare it with this idea: The number of protons defines the element.