Which isotopes are radioactive

When alpha-emitting atoms are inhaled or swallowed, however, they are especially damaging because they transfer relatively large amounts of ionizing energy to living cells. See also beta particle , gamma ray , neutron , x-ray. Atom — The smallest particle of an element that can enter into a chemical reaction. Beta Particles — Electrons ejected from the nucleus of a decaying atom.

Although they can be stopped by a thin sheet of aluminum, beta particles can penetrate the dead skin layer, potentially causing burns. They can pose a serious direct or external radiation threat and can be lethal depending on the amount received. They also pose a serious internal radiation threat if beta-emitting atoms are ingested or inhaled. See also alpha particle , gamma ray , neutron , x-ray. Decay Chain Decay Series — The series of decays that certain radioisotopes go through before reaching a stable form.

For example, the decay chain that begins with uranium U ends in lead Pb , after forming isotopes, such as uranium U , thorium Th , radium Ra , and radon Rn Gamma Rays — High-energy electromagnetic radiation emitted by certain radionuclides when their nuclei transition from a higher to a lower energy state. These rays have high energy and a short wave length. All gamma rays emitted from a given isotope have the same energy, a characteristic that enables scientists to identify which gamma emitters are present in a sample.

Gamma rays penetrate tissue farther than do beta or alpha particles , but leave a lower concentration of ions in their path to potentially cause cell damage. Gamma rays are very similar to x-rays. See also neutron. Isotope — A nuclide of an element having the same number of protons but a different number of neutrons.

Neutrons are, as the name implies, neutral in their charge. That is, they have neither a positive nor a negative charge. A neutron has about the same mass as a proton. See also alpha particle , beta particle , gamma ray , nucleon , x-ray. Radioactive Decay — Disintegration of the nucleus of an unstable atom by the release of radiation.

Radiation — Energy moving in the form of particles or waves. Familiar radiations are heat, light, radio waves, and microwaves. Ionizing radiation is a very high-energy form of electromagnetic radiation. Radioactive Material — Material that contains unstable radioactive atoms that give off radiation as they decay. Radionuclide — An unstable and therefore radioactive form of a nuclide.

Skip directly to site content Skip directly to page options Skip directly to A-Z link. Radiation and Your Health. Section Navigation. The energy liberated in the form change can be measured with a Geiger counter or with photographic film.

Each radioisotope has a characteristic disintegration or semi-life period. Energy may be liberated mostly in the form of alpha helium nuclei , beta, electrons or positrons , or gamma electromagnetic energy rays. Several unstable and artificial radioactive isotopes have medical uses. For instance, a technetium isotope 99m Tc may be used to identify blocked blood vessels.

Various natural radioactive isotopes are used to determine chronologies, such as the archeological kind 14 C. What are super lasers? Where do cosmic rays come from? A family of people often consists of related but not identical individuals.

Elements have families as well, known as isotopes. Isotopes are members of a family of an element that all have the same number of protons but different numbers of neutrons. For example, carbon has six protons and is atomic number 6. Carbon occurs naturally in three isotopes: carbon 12, which has 6 neutrons plus 6 protons equals 12 , carbon 13, which has 7 neutrons, and carbon 14, which has 8 neutrons.

Every element has its own number of isotopes. Carbon is stable, meaning it never undergoes radioactive decay. Carbon is unstable and undergoes radioactive decay with a half-life of about 5, years meaning that half of the material will be gone after 5, years.