When an antiparticle is added to an atom, it can lead to a process known as annihilation or capture, depending on the specific circumstances. Let's consider the example of adding an antiparticle to a normal matter atom:
Annihilation: If an antiparticle encounters its corresponding particle within an atom, they can undergo annihilation. Annihilation occurs when a particle and its antiparticle collide, resulting in the conversion of their mass into energy. The energy is typically released in the form of gamma rays or other high-energy particles. In this process, both the particle and antiparticle are completely destroyed.
Capture: In certain cases, an antiparticle can be captured by an atomic nucleus, resulting in the formation of a different nucleus. This process is called capture. The captured antiparticle combines with a proton or a neutron in the nucleus, causing a nuclear transformation. The specific outcome depends on the type of antiparticle involved and the nucleus it interacts with. The resulting nucleus may have different properties or be unstable, leading to subsequent radioactive decay.
It's worth noting that the behavior of antiparticles in atoms is highly dependent on their properties and the specific circumstances. For example, positrons (the antiparticles of electrons) can form "positronium" when they are captured by an electron and orbit around each other briefly before annihilating. Other antiparticles, such as antiprotons or antineutrons, can be captured by nuclei, leading to the creation of antinuclei.
In summary, when an antiparticle is added to an atom, it can undergo annihilation if it encounters its corresponding particle, resulting in the conversion of their mass into energy. Alternatively, the antiparticle can be captured by the atom's nucleus, leading to a nuclear transformation and the formation of a different nucleus.