Radiation involves parts or energy from atoms being given off, often measured with a Geiger counter. Geiger counters detect radiation through inert gases that generate an electrical charge when hit by radioactive particles. Background radiation is always present, but significant amounts can be detected from radioactive materials like Uranium-238.

The stability of an atom's nucleus depends on the balance between protons and neutrons, held together by the strong nuclear force. As atoms get larger, like Uranium with 92 protons, more neutrons are needed to counteract the repulsion between protons. Atoms often undergo decay to achieve a more stable ratio of neutrons to protons.

Scientists identified three main types of radiation using electric fields: alpha, beta, and gamma. Alpha decay involves the emission of two protons and two neutrons (a helium nucleus), can be stopped by paper, and has a positive charge. Beta decay is an electron (beta-minus) or a positron (beta-plus) emission, can be stopped by aluminum foil, and has a negative or positive charge, respectively. Gamma radiation is high-energy electromagnetic radiation, like X-rays, with no charge, and requires dense materials like lead or soil to block.

Nuclear equations represent radioactive decay and must be balanced. For example, in alpha decay, Uranium-238 loses two protons and two neutrons (a helium nucleus). This changes the atomic number to 90 and the mass number to 234, transforming Uranium into Thorium-234.

In beta-minus decay, an electron is emitted. Cesium-137, with an atomic number of 55 and mass number of 137, undergoes beta-minus decay. A neutron converts into a proton and an electron, increasing the atomic number to 56 while the mass number remains 137, thus transforming Cesium into Barium-137.

Beta-plus decay involves the emission of a positron. Sodium-22, with an atomic number of 11 and mass number of 22, undergoes beta-plus decay. A proton converts into a neutron and a positron, decreasing the atomic number by one to 10 while the mass number remains 22, transforming Sodium into Neon-22.