The Atom Builder lets you create atoms from scratch and discover how each subatomic particle affects their properties. Experiment with different combinations and observe how the element's identity, stability, electrical charge, and electron configuration change.
In the "Build Your Atom" section, you will find three counters that let you adjust the number of protons, neutrons, and electrons. Use the + and − buttons to add or remove particles, or drag them directly into the atom shown in the diagram. • Protons: determine which chemical element you are building. Each element has a unique number of protons. For example, 6 protons correspond to carbon and 8 to oxygen. • Neutrons: together with protons, they form the nucleus. By changing their number, you can explore different isotopes of the same element. • Electrons: are distributed around the nucleus and determine the electrical charge of the atom or ion.
In "See an Element's Atom", you can search for an element by its name, chemical symbol, or atomic number (Z). When you select an element, the system displays its neutral atom and automatically adjusts the particle counts. You can then modify them to experiment with other configurations.
The "Element" section identifies the element when there are enough protons to determine its identity. It also displays its atomic number and reference atomic mass. The stability indicator reports the estimated nuclear stability of the combination of protons and neutrons. If the nucleus is marked as stable, the ratio between these particles is compatible with a stable nucleus according to the model used. If it is marked as unstable, the nucleus corresponds to a radioactive combination that may transform over time. If there are not yet enough protons, the system will prompt you to add more before evaluating the result. The net charge is calculated by subtracting the number of electrons from the number of protons. If both counts are equal, the atom is neutral. If it has more protons, its charge is positive; if it has more electrons, its charge is negative.
The "Statistics" panel summarizes the main data about your atom: • Protons, neutrons, and electrons: the number of each particle. • Mass number: the sum of the protons and neutrons in the nucleus. • n/p ratio: the ratio of neutrons to protons, which helps explain nuclear stability. • Electron configuration: the distribution of electrons across the shells, expressed as numbers such as 2, 8, 7. Try different combinations and watch how the results change! Keep in mind that the diagram uses a simplified representation of the Bohr model of the atom: real electrons do not follow fixed orbits, and the sizes and distances shown are not to scale.