- Key People:
- Marie Curie
- Pierre Curie
- Related Topics:
- chemical element
- oxygen group element
- polonium-210
polonium
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What is polonium?
Polonium (Po) is a radioactive, silvery-gray or black metallic element discovered in 1898 by Marie and Pierre Curie. It is named after Poland, Marie Curie's homeland. Polonium is extremely rare, found naturally as a decay product of uranium, thorium, and actinium. Its most common natural isotope, polonium-210, has a half-life of 138.4 days.
Chemically, polonium resembles tellurium and bismuth. Due to its high radioactivity, it emits alpha particles and must be handled with extreme care. Industrially, polonium is used to eliminate static electricity and as a source of alpha radiation in physics.
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Who discovered polonium and when?
Polonium was discovered in 1898 by Pierre and Marie Curie. They identified it through their investigation of the radioactivity of pitchblende, a uranium ore. The intense radioactivity they detected, which could not be attributed to uranium alone, led them to hypothesize the existence of a new element. They named it polonium in honor of Marie Curie's native country, Poland. This discovery marked polonium as the first element identified through radiochemical analysis.
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Where is polonium found in nature?
Polonium is an extremely rare element found in nature. Its abundance in Earth's crust is estimated to be about one part in 1015. Polonium occurs as a radioactive decay product of uranium, thorium, and actinium. While it can be found in uranium ores like pitchblende, it is present in very small quantities. For instance, 1,000 tons of pitchblende are needed to yield just 40 milligrams of polonium. It is typically isolated from the by-products generated during the extraction of radium from uranium minerals.
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What are some key properties of polonium?
Polonium (Po) is a radioactive, silvery-gray or black metallic element discovered in 1898 by Marie and Pierre Curie. It is extremely rare, found as a decay product of uranium, thorium, and actinium. The most common natural isotope, polonium-210, has a half-life of 138.4 days.
Chemically, polonium resembles tellurium and bismuth. Due to its intense radioactivity, polonium must be handled with extreme care. Industrially, it is used to eliminate static electricity and as a source of alpha radiation in physics research. Mixtures of polonium with light elements serve as neutron sources. Polonium decays by emitting alpha rays, transforming into a stable isotope of lead.
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Why is polonium considered dangerous?
Polonium is considered dangerous due to its extreme radioactivity. It is a radioactive element that disintegrates by emitting alpha rays, which are streams of positively charged particles. Alpha particles cause intense ionization in tissues, leading to significant biological damage, such as attacks on DNA and proteins. While alpha particles do not penetrate deeply, their destructive effect is far greater than that of gamma rays, and they can cause tumors at their storage site within the body. Polonium is also a decay product of uranium and thorium, making it a naturally occurring radioactive substance.
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How is polonium used in science or industry?
Polonium's intense radioactivity leads to its use in specific industrial and scientific applications. It is employed to eliminate static electricity in processes like paper rolling and synthetic fiber spinning. Additionally, polonium serves as a source of alpha radiation in nuclear physics and, when mixed with beryllium, acts as a neutron source.
Polonium is extremely rare and highly radioactive, emitting alpha rays. Due to its hazardous nature, it must be handled with extreme caution. Its primary natural isotope, polonium-210, has a half-life of 138.4 days.
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polonium (Po), a radioactive, silvery-gray or black metallic element of the oxygen group (Group 16 [VIa] in the periodic table). The first element to be discovered by radiochemical analysis, polonium was discovered in 1898 by Pierre and Marie Curie, who were investigating the radioactivity of a certain pitchblende, a uranium ore. The very intense radioactivity not attributable to uranium was ascribed to a new element, named by them after Marie Curie’s homeland, Poland. The discovery was announced in July 1898. Polonium is extremely rare, even in pitchblende: 1,000 tons of the ore must be processed to obtain 40 milligrams of polonium. Its abundance in the Earth’s crust is about one part in 1015. It occurs in nature as a radioactive decay product of uranium, thorium, and actinium. The half-lives of its isotopes range from a fraction of a second up to 103 years; the most common natural isotope of polonium, polonium-210, has a half-life of 138.4 days.
Polonium usually is isolated from by-products of the extraction of radium from uranium minerals. In the chemical isolation, pitchblende ore is treated with hydrochloric acid, and the resulting solution is heated with hydrogen sulfide to precipitate polonium monosulfide, PoS, along with other metal sulfides, such as that of bismuth, Bi2S3, which resembles polonium monosulfide closely in chemical behaviour, though it is less soluble. Because of the difference in solubility, repeated partial precipitation of the mixture of sulfides concentrates the polonium in the more soluble fraction, while the bismuth accumulates in the less soluble portions. The difference in solubility is small, however, and the process must be repeated many times to achieve a complete separation. Purification is accomplished by electrolytic deposition. It can be produced artificially by bombarding bismuth or lead with neutrons or with accelerated charged particles.
Chemically, polonium resembles the elements tellurium and bismuth. Two modifications of polonium are known, an α- and a β-form, both of which are stable at room temperature and possess metallic characteristics. The fact that its electrical conductivity decreases as the temperature increases places polonium among the metals rather than the metalloids or nonmetals.
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Because polonium is highly radioactive—it disintegrates to a stable isotope of lead by emitting alpha rays, which are streams of positively charged particles—it must be handled with extreme care. When contained in such substances as gold foil, which prevent the alpha radiation from escaping, polonium is used industrially to eliminate static electricity generated by such processes as paper rolling, the manufacture of sheet plastics, and the spinning of synthetic fibres. It is also used on brushes for removing dust from photographic film and in nuclear physics as a source of alpha radiation. Mixtures of polonium with beryllium or other light elements are used as sources of neutrons.
| atomic number | 84 |
|---|---|
| atomic weight | 210 |
| melting point | 254 °C (489 °F) |
| boiling point | 962 °C (1,764 °F) |
| density | 9.4 g/cm3 |
| oxidation states | −2, +2, +3(?), +4, +6 |
| electron config. | 1s22s22p63s23p63d104s24p64d104f145s25p65d106s26p4 |