Radium-226

Last updated
Radium-226, 226Ra
General
Symbol 226Ra
Names radium-226, 226Ra, Ra-226
Protons (Z)88
Neutrons (N)138
Nuclide data
Natural abundance trace
Half-life (t1/2)1600 years [1]
Isotope mass 226.025408 [2] Da
Spin 0+
Parent isotopes 230Th  (α)
226Fr  (β)
Decay products 222Rn
Decay modes
Decay mode Decay energy (MeV)
alpha decay 4.870 [1]
Isotopes of radium
Complete table of nuclides

Radium-226 (226
Ra
) is the longest-lived isotope of radium, with a half-life of 1600 years. It is an intermediate product in the decay chain of uranium-238; as such, it can be found naturally in uranium-containing minerals.

Contents

Occurrence and decay

The decay-chain of uranium-238, which contains radium-226 as an intermediate decay product Decay chain(4n+2, Uranium series).svg
The decay-chain of uranium-238, which contains radium-226 as an intermediate decay product

226
Ra
occurs in the decay chain of uranium-238 (238
U
), which is the most common naturally occurring isotope of uranium. It undergoes alpha decay to radon-222, which is also radioactive; the decay chain ultimately terminates at lead-206.

Because of its occurrence in the 238
U
decay chain, 226
Ra
exists naturally at low concentrations in uranium-containing minerals, soil, and groundwater. [3]

Historical uses

Following its discovery by Marie and Pierre Curie in 1898, radium (principally 226
Ra
) has had a number of uses. In the early 20th century, when the hazards of radiation were not well-known, radium was commonly used in consumer items such as toothpaste and hair creams. Radium was also formerly used as a radiation source for cancer treatment, but has since been replaced in this role by safer and more easily available alternatives. Until the 1960s, radium was used in luminous paint for watch dials and aircraft instruments. [4]

Hazards

As a radioactive material, 226
Ra
and its decay products can present serious health hazards. Factory workers who worked with radium-containing luminous paint, known as the Radium Girls, often licked the tips of their paintbrushes in order to produce a finer point. In doing so, the workers ingested some of the radioactive paint; this eventually led to serious health problems including cancer, bone damage, and anemia. Several of these workers died from illnesses caused by radium exposure. [5]

Many rocks and soils contain low concentrations of 226
Ra
, which forms from the radioactive decay of naturally occurring uranium. The decay of 226
Ra
produces radon-222, a radioactive gas that can accumulate in inadequately ventilated homes and other enclosed spaces. Radon exposure is the second leading cause of lung cancer in the United States. [3]

Related Research Articles

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<span class="mw-page-title-main">Polonium</span> Chemical element with atomic number 84 (Po)

Polonium is a chemical element; it has symbol Po and atomic number 84. A rare and highly radioactive metal with no stable isotopes, polonium is a chalcogen and chemically similar to selenium and tellurium, though its metallic character resembles that of its horizontal neighbors in the periodic table: thallium, lead, and bismuth. Due to the short half-life of all its isotopes, its natural occurrence is limited to tiny traces of the fleeting polonium-210 in uranium ores, as it is the penultimate daughter of natural uranium-238. Though longer-lived isotopes exist, such as the 124 years half-life of polonium-209, they are much more difficult to produce. Today, polonium is usually produced in milligram quantities by the neutron irradiation of bismuth. Due to its intense radioactivity, which results in the radiolysis of chemical bonds and radioactive self-heating, its chemistry has mostly been investigated on the trace scale only.

<span class="mw-page-title-main">Radium</span> Chemical element with atomic number 88 (Ra)

Radium is a chemical element; it has symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, but it readily reacts with nitrogen (rather than oxygen) upon exposure to air, forming a black surface layer of radium nitride (Ra3N2). All isotopes of radium are radioactive, the most stable isotope being radium-226 with a half-life of 1,600 years. When radium decays, it emits ionizing radiation as a by-product, which can excite fluorescent chemicals and cause radioluminescence.

Radon is a chemical element; it has symbol Rn and atomic number 86. It is a radioactive noble gas and is colorless and odorless. Of the three naturally occurring radon isotopes, only radon-222 has a sufficiently long half-life for it to be released from the soil and rock where it is generated. Radon isotopes are the immediate decay products of radium isotopes. The instability of radon-222, its most stable isotope, makes radon one of the rarest elements. Radon will be present on Earth for several billion more years, despite its short half-life, because it is constantly being produced as a step in the decay chain of uranium-238, and that of thorium-232, each of which is an extremely abundant radioactive nuclide with a half-life of several billion years. The decay of radon produces many other short-lived nuclides, known as "radon daughters", ending at stable isotopes of lead. Radon-222 occurs in significant quantities as a step in the normal radioactive decay chain of uranium-238, also known as the uranium series, which slowly decays into a variety of radioactive nuclides and eventually decays into lead-206, which is stable. Radon-220 occurs in minute quantities as an intermediate step in the decay chain of thorium-232, also known as the thorium series, which eventually decays into lead-208, which is stable.

<span class="mw-page-title-main">Uranium</span> Chemical element with atomic number 92 (U)

Uranium is a chemical element; it has symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium radioactively decays, usually by emitting an alpha particle. The half-life of this decay varies between 159,200 and 4.5 billion years for different isotopes, making them useful for dating the age of the Earth. The most common isotopes in natural uranium are uranium-238 and uranium-235. Uranium has the highest atomic weight of the primordially occurring elements. Its density is about 70% higher than that of lead and slightly lower than that of gold or tungsten. It occurs naturally in low concentrations of a few parts per million in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite.

<span class="mw-page-title-main">Pleochroic halo</span> Geological phenomenon

A pleochroic halo, or radiohalo, is a microscopic, spherical shell of discolouration (pleochroism) within minerals such as biotite that occurs in granite and other igneous rocks. The halo is a zone of radiation damage caused by the inclusion of minute radioactive crystals within the host crystal structure. The inclusions are typically zircon, apatite, or titanite which can accommodate uranium or thorium within their crystal structures. One explanation is that the discolouration is caused by alpha particles emitted by the nuclei; the radius of the concentric shells are proportional to the particles' energy.

<span class="mw-page-title-main">Decay chain</span> Series of radioactive decays

In nuclear science, the decay chain refers to a series of radioactive decays of different radioactive decay products as a sequential series of transformations. It is also known as a "radioactive cascade". The typical radioisotope does not decay directly to a stable state, but rather it decays to another radioisotope. Thus there is usually a series of decays until the atom has become a stable isotope, meaning that the nucleus of the atom has reached a stable state.

<span class="mw-page-title-main">Uranium-238</span> Isotope of uranium

Uranium-238 is the most common isotope of uranium found in nature, with a relative abundance of 99%. Unlike uranium-235, it is non-fissile, which means it cannot sustain a chain reaction in a thermal-neutron reactor. However, it is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to fissile plutonium-239. 238U cannot support a chain reaction because inelastic scattering reduces neutron energy below the range where fast fission of one or more next-generation nuclei is probable. Doppler broadening of 238U's neutron absorption resonances, increasing absorption as fuel temperature increases, is also an essential negative feedback mechanism for reactor control.

Polonium-210 (210Po, Po-210, historically radium F) is an isotope of polonium. It undergoes alpha decay to stable 206Pb with a half-life of 138.376 days (about 4+12 months), the longest half-life of all naturally occurring polonium isotopes (210–218Po). First identified in 1898, and also marking the discovery of the element polonium, 210Po is generated in the decay chain of uranium-238 and radium-226. 210Po is a prominent contaminant in the environment, mostly affecting seafood and tobacco. Its extreme toxicity is attributed to intense radioactivity, mostly due to alpha particles, which easily cause radiation damage, including cancer in surrounding tissue. The specific activity of 210
Po
is 166 TBq/g, i.e., 1.66 × 1014 Bq/g. At the same time, 210Po is not readily detected by common radiation detectors, because its gamma rays have a very low energy. Therefore, 210
Po
can be considered as a quasi-pure alpha emitter.

<span class="mw-page-title-main">Radioluminescence</span> Light produced in a material by bombardment with ionizing radiation

Radioluminescence is the phenomenon by which light is produced in a material by bombardment with ionizing radiation such as alpha particles, beta particles, or gamma rays. Radioluminescence is used as a low level light source for night illumination of instruments or signage. Radioluminescent paint is occasionally used for clock hands and instrument dials, enabling them to be read in the dark. Radioluminescence is also sometimes seen around high-power radiation sources, such as nuclear reactors and radioisotopes.

Luminous paint is paint that emits visible light through fluorescence, phosphorescence, or radioluminescence.

Radionuclides which emit gamma radiation are valuable in a range of different industrial, scientific and medical technologies. This article lists some common gamma-emitting radionuclides of technological importance, and their properties.

<span class="mw-page-title-main">Actinides in the environment</span>

Environmental radioactivity is not limited to actinides; non-actinides such as radon and radium are of note. While all actinides are radioactive, there are a lot of actinides or actinide-relating minerals in the Earth's crust such as uranium and thorium. These minerals are helpful in many ways, such as carbon-dating, smoke detectors, X-rays, and more.

<span class="mw-page-title-main">Environmental radioactivity</span> Radioactivity naturally present within the Earth

Environmental radioactivity is part of the overall background radiation and is produced by radioactive materials in the human environment. While some radioisotopes, such as strontium-90 (90Sr) and technetium-99 (99Tc), are only found on Earth as a result of human activity, and some, like potassium-40 (40K), are only present due to natural processes, a few isotopes, e.g. tritium (3H), result from both natural processes and human activities. The concentration and location of some natural isotopes, particularly uranium-238 (238U), can be affected by human activity, such as nuclear weapons testing, which caused a global fallout, with up to 2.4 million deaths by 2020.

<span class="mw-page-title-main">Radium and radon in the environment</span> Significant contributors to environmental radioactivity

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Naturally occurring radioactive materials (NORM) and technologically enhanced naturally occurring radioactive materials (TENORM) consist of materials, usually industrial wastes or by-products enriched with radioactive elements found in the environment, such as uranium, thorium and potassium and any of their decay products, such as radium and radon. Produced water discharges and spills are a good example of entering NORMs into the surrounding environment.

Radon-222 is the most stable isotope of radon, with a half-life of approximately 3.8 days. It is transient in the decay chain of primordial uranium-238 and is the immediate decay product of radium-226. Radon-222 was first observed in 1899, and was identified as an isotope of a new element several years later. In 1957, the name radon, formerly the name of only radon-222, became the name of the element. Owing to its gaseous nature and high radioactivity, radon-222 is one of the leading causes of lung cancer.

The health effects of radon are harmful, and include an increased chance of lung cancer. Radon is a radioactive, colorless, odorless, tasteless noble gas, which has been studied by a number of scientific and medical bodies for its effects on health. A naturally-occurring gas formed as a decay product of radium, radon is one of the densest substances that remains a gas under normal conditions, and is considered to be a health hazard due to its radioactivity. Its most stable isotope, radon-222, has a half-life of 3.8 days. Due to its high radioactivity, it has been less well studied by chemists, but a few compounds are known.

References

  1. 1 2 National Nuclear Data Center. "NuDat 3.0 database". Brookhaven National Laboratory . Retrieved March 4, 2024.
  2. Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
  3. 1 2 "Radionuclide Basics: Radium". epa.gov. 15 April 2015. Retrieved March 4, 2024.
  4. "Radium". nrc.gov. Retrieved March 4, 2024.
  5. Arlene Balkansky (March 19, 2019). "Radium Girls: Living Dead Women". Library of Congress Blogs. Retrieved March 4, 2024.