What is the process that leads to the removal of orbital electrons from atoms?

The correct answer is ionization. This process specifically refers to the removal of electrons from an atom, transforming it into an ion. When enough energy is provided—either from an electromagnetic source like radiation or through other energetic interactions—electrons can be knocked out of their orbits around the nucleus.

Ionization plays a crucial role in various fields, including radiation safety, as it is fundamental to understanding how radiation interacts with matter. For instance, in the case of ionizing radiation, such as X-rays or gamma rays, this interaction can lead to biological damage, which is why monitoring exposure levels is essential.

The other processes listed, while related to atomic interactions, do not result in the removal of electrons in the same manner. Radioactive decay involves the transformation of unstable nuclei into more stable configurations, often leading to the emission of radiation but not directly targeting electron removal. Excitation, on the other hand, is when electrons absorb energy and move to a higher energy level without leaving the atom entirely—they are still bound to the nucleus. Radiation absorption refers to the process where matter absorbs incoming energy, which may lead to either ionization or excitation, but it is not a process that directly describes the removal of electrons.