Final answer:
Free radicals are highly reactive species with unpaired electrons that can cause cellular damage due to their chemical activity. They are not isotopes, fusion particles, or alpha particles, but are instead formed through processes like ionizing radiation.
Step-by-step explanation:
Substances that are missing some electrons and are extremely chemically active are known as Free Radicals. These are not isotopes, fusion particles, or alpha particles. Instead, they are highly reactive species with unpaired electrons that may bond to other atoms to achieve stability. This reactivity makes free radicals potentially dangerous due to their tendency to react with essential biological molecules, leading to cellular damage. These particles are indicated by a radical dot notation such as the hydroxyl radical (OH·) or the chlorine atom (Cl·). They are typically short-lived and look to form more stable molecules rapidly.
Ionizing radiation, such as ultra-violet radiation, X-rays, and gamma rays, can produce free radicals by breaking molecular bonds, which is why exposure to these forms of radiation can be harmful to living organisms. This form of radiation is powerful enough to ionize atoms and molecules, leading to chemical reactions that can harm biological tissues.