A visual guide, starting from scratch
How radioactive decay actually works
Alpha, beta-minus, beta-plus, electron capture and gamma decay explained at the level of protons, neutrons and quarks, with step-by-step animations. No physics background needed.
The three things to understand first
Does something hit the nucleus?
No. A radioactive nucleus is already unstable. At a random moment it falls into a lower-energy arrangement by itself. Nothing from outside triggers it.
More in chapter 2 → Where does the energy come from?
Mass. The pieces left after a decay weigh slightly less than the original nucleus. That missing mass turns into the energy of the particles flying out (E = mc²).
More in chapter 2 → When does it happen?
At random. You can't predict any single nucleus. With billions of them, half always decay in a fixed time, called the half-life .
More in chapter 2 →
The five decays in one line each
"Element" is the change in proton count. Changing the proton count changes which element the atom is.
Colour key
Every diagram in this guide uses the same colours:
Chapters
⚛
Chapter 1 Particles & forcesQuarks, protons, neutrons, electrons, neutrinos, and the three forces that fight inside a nucleus. E
Chapter 2 Energy & randomnessWhy nothing has to hit a nucleus, where the energy comes from (E = mc²), and what a half-life really means. α
Chapter 3 Alpha decayA heavy nucleus ejects a 2-proton, 2-neutron chunk by quantum tunneling through an energy wall. β⁻
Chapter 4 Beta-minus decayA neutron becomes a proton: a down quark turns into an up quark and an electron + antineutrino are created. β⁺
Chapter 5 Beta-plus (positron) decayA proton becomes a neutron and emits a positron (antimatter electron) plus a neutrino. EC
Chapter 6 Electron captureThe nucleus absorbs one of its own inner electrons, turning a proton into a neutron. γ
Chapter 7 Gamma decayAn excited nucleus settles down and sheds its extra energy as one high-energy photon. Σ
Chapter 8 Putting it togetherHow far each radiation travels, all five decays side by side, and the single recipe behind them. ?
Chapter 9 Common confusionsWhen things really do hit nuclei, whether decay can be sped up, gamma vs X-rays, decay chains, and more.