Modern Physics · Physics

Build an Atom Simulation

Build an atom from protons, neutrons and electrons. See the element, its charge, its mass number and its symbol update as you go — then test yourself in the game.

Interactive virtual lab · no download · works on phones and laptops

Chapter: Structure of the Atom
For: Class 9 · Class 11
Time: ~10 min

Build an Atom is a Pro simulation

Pro opens all 125 virtual labs — 483 simulations with guides and quizzes.

How to use it

1Add or remove each particle with + and −, or tap the buckets.
2Read the element, charge and mass panels.
3Switch on the symbol view.
4Play the game: build the atom asked for.

What to notice

The number of protons decides the element.
Charge = protons − electrons; an atom with a charge is an ion.
Mass number = protons + neutrons; electrons barely add mass.
Electrons fill shells of 2, 8, 8 …

For teachers

A ready-made teaching kit comes with this lab

Lesson plan
19 min, 4 steps
Ask the class
3 questions with answers
Quick quiz
6 questions, printable
Key formulas
2 formulas

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About the Build an Atom simulation

An atom has a tiny nucleus of protons and neutrons surrounded by electrons. The number of protons decides the element, protons plus neutrons give the mass number, and protons minus electrons give the charge. An atom with extra or missing electrons is an ion.

In this build an atom simulation you drag protons, neutrons and electrons into an atom and read off its element, symbol, mass number and charge, shown as shells or as an electron cloud, then test yourself in the game. It covers Structure of the Atom in Class 9 and Class 11 chemistry.

Also covers: protons, neutrons, electrons, ion, isotope, atomic number, mass number, chemistry.