Polonium (Po)
He polonium (Po) it is a very rare and highly volatile radioactive metal. Before the Polish-French physicist Marie Curie discovered polonium in 1898, uranium and thorium were the only known radioactive elements.
Polonium: A rare and highly volatile radioactive element. Curie named him Polonius after her homeland of Poland.
Polonium is of little use to humans, except for a few threatening applications: It was used as a detonator in the first atomic bomb, and it’s also a suspected poison in a couple of high-profile deaths.
In commercial applications, polonium is occasionally used to remove static electricity from machinery or dust from photographic film. It can also be used as a light heat source for thermoelectric power on space satellites.
Classification
Polonium is in Group 16 and in period 6 of the periodic table of elements. It is classified as a metal because polonium’s electrical conductivity decreases as its temperature increases, according to the Royal Society of Chemistry.
The element is the heaviest metal of the chalcogens, a group of elements also known as the «oxygen family.» All chalcogens are found in copper ores. Other elements in the chalcogen group include oxygen, sulfur, selenium, and tellurium.
There are 33 known isotopes (atoms of the same element with different numbers of neutrons) of polonium, and all are radioactive. The radioactive instability of this element is what makes it a prime candidate for use in atomic bombs.
physical characteristics
Atomic number (number of protons in the nucleus): 84
Atomic symbol (in the periodic table of elements): Po
Atomic weight (average mass of the atom): 209
Density: 9.32 grams per cubic centimeter
Phase at room temperature: Solid
Melting point: 489.2 degrees Fahrenheit (254 degrees Celsius)
Boiling point: 1,763.6 degrees F (962 degrees C)
The most common isotope: Po-210 which has a half-life of only 138 days
Discovery of Polonium
When Curie and her husband, Pierre Curie, discovered polonium, they were looking for the source of radioactivity in a naturally occurring uranium-rich mineral called pitchblende.
The two noted that the unrefined pitchblende was more radioactive than the uranium that had been separated from it. So, they reasoned that the pitchblende must be harboring at least one other radioactive element.
The Curies bought loads of pitchblende so that they could chemically separate the compounds from the minerals.
After months of hard work, they finally isolated the radioactive element: a substance 400 times more radioactive than uranium, according to the International Union of Pure and Applied Chemistry (IUPAC).
The extraction of polonium was challenging because there was such a minuscule amount; a ton of uranium ore contains only about 100 micrograms (0.0001 grams) of polonium.
However, the Curies were able to extract the isotope we now know as polonium-209, according to the Royal Society of Chemistry.
Sources
Traces of Po-210 can be found in the soil and in the air. For example, Po-210 is produced during the decay of the gas radon-222, which is the result of the decay of radium.
In turn, radium is a decay product of uranium, which is present in almost all rocks and soils formed from rocks.
Lichens are capable of absorbing polonium directly from the atmosphere. In northern areas, people who eat reindeer may have higher concentrations of polonium in their blood, because reindeer eat lichen, according to Smithsonian.com.
Polonium is considered a rare natural element. Although it is found in uranium ores, it is not economical to mine since there are only about 100 micrograms of polonium in 1 ton (0.9 metric tons) of uranium ore, according to the Jefferson Lab.
Instead, polonium is made by bombarding bismuth-209 (a stable isotope) with neutrons in a nuclear reactor.
This creates radioactive bismuth-210, which then breaks down into polonium through a process called beta decay, according to the Royal Society of Chemistry.
The United States Nuclear Regulatory Commission estimates that only about 100 grams (3.5 ounces) of polonium-210 is produced worldwide each year.
commercial uses
Due to its high radioactivity, polonium has few commercial applications. Limited uses for the item include removing static electricity from machinery and removing dust from photographic film.
In both applications, the polonium must be carefully sealed to protect the user.
The element is also used as a light heat source for thermoelectric power in satellites and other spacecraft.
This is because polonium breaks down quickly, and in doing so, it releases a large amount of energy in the form of heat. Just one gram of polonium will reach a temperature of 500 degrees C (932 degrees F) as it breaks down, according to the Royal Society of Chemistry.
Atomic bomb
In the middle of World War II, the Army Corps of Engineers began organizing the Manhattan Engineer District, a top-secret research and development program that would ultimately produce the world’s first nuclear weapons.
Before the 1940s, there was no reason to isolate polonium in its pure form or to produce it in any substantial quantity, because its use was unknown and very little was known about it.
But district engineers began studying polonium and found the element to be an important ingredient for their nuclear weapon.
A combination of polonium and beryllium, another rare element, acted as the bomb’s primer, according to the Atomic Heritage Foundation.
After the war, the polonium research project was transferred to the Mound Laboratory in Miamisburg, Ohio. Completed in 1949, Mound Lab was the Atomic Energy Commission’s first permanent facility for nuclear weapons development.
Poisoning
Polonium is toxic to humans, even in very small amounts.
The first person to die of polonium poisoning may have been Marie Curie’s daughter, Irène Joliot-Curie.
In 1946, a polonium capsule exploded in his laboratory bench, which may have been the reason he contracted leukemia and died 10 years later.
Polonium poisoning was also what killed Alexander Litvinenko, a former Russian spy who had been living in London in 2006 after applying for political asylum.
Poisoning was also suspected in the death of Palestinian leader Yasser Arafat in 2004, when shockingly high levels of polonium-210 were detected in his clothing, according to The Wall Street Journal.
A 2011 study published in the journal Nicotine & Tobacco Research found that tobacco companies have been aware that cigarettes and other tobacco-containing products contain low levels of polonium.
The study authors calculated that radioactivity from polonium in cigarettes is responsible for up to 138 deaths per 1,000 smokers over a 25-year period.
Other research has shown that twice as much polonium is found in the ribs of smokers than non-smokers, according to the US National Institutes of Health Toxicology Data Network.
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