When an unstable atom undergoes radioactive decay, it can lose mass over time. This weight loss occurs due to the conversion of mass into energy during the decay process. According to Einstein's famous equation, E = mc², energy (E) is directly proportional to mass (m) and the square of the speed of light (c).
During radioactive decay, a portion of the atom's mass is converted into various forms of energy, such as gamma rays, alpha particles, beta particles, or neutrinos. This energy is released from the atom as it transitions to a more stable configuration.
For example, in alpha decay, an unstable atom emits an alpha particle, which consists of two protons and two neutrons. The combined mass of the alpha particle is slightly less than the mass of the original atom. The "missing" mass is converted into energy according to Einstein's equation. Similar principles apply to other types of radioactive decay.
It's important to note that the overall conservation of mass and energy is still maintained. While the atom loses mass, the total mass and energy of the system (including the atom, its decay products, and any emitted radiation) remain constant.