To cause an atom or molecule to gain or lose one or more electrons, producing an electrically charged particle called an ion.
When an atom or molecule ionizes, its number of electrons changes. Losing electrons produces a positively charged ion, while gaining electrons produces a negatively charged ion. Ionization can occur when matter absorbs enough energy from sources such as high-energy radiation.
Ionization is important in medicine because ionizing radiation can alter molecules in cells, including DNA. This property makes ionizing radiation useful for medical imaging and radiation therapy but also means that excessive exposure can cause biological damage.
QUICK FACT
Ionization is specifically about a change in electrical charge caused by gaining or losing electrons. It is not simply the same as heating or exciting an atom.
COMMONLY CONFUSED WITH
- Ion: an atom or molecule that has gained or lost electrons and therefore carries an electrical charge.
- Excitation: when an atom or molecule gains energy without necessarily losing or gaining an electron.
- Ionizing radiation: radiation with enough energy to cause ionization.
SEE ALSO