Who discovered polonium. Polonium: the history of the discovery of the element. The culprits are harder to find

Polonium (Latin: Polonium; denoted by the Po symbol) is a chemical element with atomic number 84 in the periodic system, a radioactive semimetal of silver-white color. It does not have stable isotopes.

History and origin of the name

The element was discovered in 1898 by the spouses Pierre Curie and Maria Skłodowska Curie in resin tarble. The element was named in honor of the homeland of Maria Skłodowska-Curie - Poland (lat. Polonia).
  In 1902, the German scientist Wilhelm Marquald discovered a new element. He called it radiotellur. Curie, reading a note about the discovery, said that this is an element of polonium, discovered by them four years earlier. Marquald did not agree with this assessment, saying that polonium and radiotellurium are different elements. After a series of experiments with the element, the Curie spouses proved that polonium and radiotellurium have the same half-life. Marquald was forced to retreat.
  The first polonium sample containing 0.1 mg of this element was isolated in 1910.

The properties

Polonium is a soft silver-white radioactive metal.
  Metallic polonium is rapidly oxidized in air. Polonium dioxide (PoO 2) x and polonium monoxide PoO are known. With halogens forms tetrahalides. Under the action of acids, it passes into the solution with the formation of pink cations Po 2+:
  Po + 2HCl → PoCl 2 + H 2.

When dissolving polonium in hydrochloric acid in the presence of magnesium, hydrogen sulfide is formed:
  Po + Mg + 2HCl → MgCl 2 + H 2 Po,

Which at room temperature is in a liquid state (from −36.1 to 35.3 ° C)
  In indicator amounts, acid polonium polonium RoO 3 and salts of polonic acid, which does not exist in the free state, K 2 RoO 4 polonates, were obtained. Polonium dioxide PoO 2 is also known. Forms halides of PoX 2, PoX 4 and PoX 6. Like tellurium, polonium is able to form chemical compounds - polonides - with a number of metals.
  Polonium is the only chemical element that, at low temperature, forms a monoatomic simple cubic crystal lattice.

Getting

In practice, in gram quantities, polonium nuclide 210 Po is synthesized artificially by irradiating metallic 209 Bi with neutrons in nuclear reactors. The resulting 210 Bi due to β decay turns into 210 Po. When the same bismuth isotope is irradiated with protons by the reaction
209 Bi + p → 209 Po + n
  the longest-lived isotope of polonium 209 Po is formed.
  Micro amounts of polonium are recovered from uranium ore processing wastes. Polonium is isolated by extraction, ion exchange, chromatography and sublimation.
  Metallic Po is obtained by vacuum thermal decomposition of PoS sulfide or dioxide (PoO 2) x at 500 ° C.
  98% of global polonium production is in Russia.

The history of the radioactive chemical element polonium-210 begins in 1898, when it was discovered by the Curie couple in one of the uranium tar ores. The element was named after Poland - the homeland of the discoverers (lat. Polonium). It was Irene Curie, according to one version, who became the first victim of the element, as she once admitted that a test tube with polonium broke in her laboratory. A decade later, she died of cancer.

History of polonium-210 poisoning in history

Different versions of the frequent cases of cancer began to come later from many parts of the world from research centers and institutes.

Also, at first there were all kinds of rumors about the involvement of the polonium-210 substance in the death of Palestinian leader Yasser Arafat, since traces of this element were found among the personal belongings of the victim. But, despite the initiation of a criminal case, the causes of death were not fully clarified and all the guesses that the attempt was committed by the Israeli secret services, then remained guesses. However, in 2012, the body was exhumed and the collected material was transferred to the study and the verdict of independent experts from different countries. The top three laboratories included institutions in France, Switzerland and Russia. A year later, the first research results were prepared, which came from the Swiss Lausanne and were handed over for review to the Palestinian capital. Following in the Palestinian city of Ramallah, the results of research by scientists from other countries were also transmitted.

The results of the examinations were received directly by the widow of Yasser Arafat, from whom the whole outside world received information that confirmed an early version of the fact that the leader was really poisoned with polonium-210.

Polonium-210 poisoning also occurred at former FSB officer Alexander Litvinenko as a result of the alleged assassination attempt on him by his former employees and colleagues in London. This has become one of the most striking and resonant cases of international scandal, and the investigation of the case has been going on so far, for more than 10 years. He died a painful death in a London hospital after 22 two days of severe suffering, when at first his leukocytes almost disappeared, then his bone marrow began to contract, and then his liver, kidneys, and heart failed.

Litvinenko case

As the investigation showed, on November 1, 2016, in the lobby of the fashionable London hotel Millennium, Alexander Litvinenko met with former colleagues Andrei Lugov and Dmitry Kovtun, where poison was added to tea. As a result of poisoning with deadly tea, Litvinenko felt unwell in the evening, and frequent vomiting began. On November 4, Litvinenko was hospitalized at the district hospital, and already 17 at the University College Hospital (UCH). November 20, he was transferred to intensive care.

This case was taken under control by the anti-terrorist unit of Scotland Yard, which conducted an investigation into the causes of poisoning, and actions were taken to detect the poisonous substance. In addition to a wide variety of analyzes, a gamma-ray radiation detector was used, which detects the content of most toxic substances if they are contained in bio-samples, but nothing was found. Then, samples of biomaterials were transferred to the atomic energy research institute, where they were engaged in the development and creation of atomic warheads. The content of polonium was discovered by scientists quite by accident  - the described isotope behavior was discussed aloud between experts, and they were heard by a developer related to a nuclear reactor, who immediately recognized the behavior of polonium, since polonium-210 is part of atomic weapons.

On the day that the cause of poisoning was discovered, November 23, Litvinenko died. An investigation of the special services found traces of a rare isotope in places visited by alleged killers - Andrei Lugovoi and Dmitry Kovtun - in an airplane, at a stadium, in a cafe, hotel, restaurants and cafes.

Polonium-210 was discovered:

• on the plane in which Lugovoi flew to Moscow after the incident;
• in the house of A. Litvinenko;
• at Heathrow Airport;
• at Easton Road Hospital;
• at the office of a security company in Gronover Street;
• in hotels Millennium, Sheraton Park Lane;
• in its sushi bar;
• in the office of B. Berezovsky.

The day after the death of her husband, the widow Maria Litvinenko was forced to leave her apartment - she was given only 20 minutes to gather. According to investigators, such measures were necessary for her safety - the apartment was seriously infected with radiation. On December 1, the widow will still be hospitalized with an increased content of polonium-210 in the body.

The panic because of the possible massive contamination with polonium-210 swept the entire city; analyzes were taken from visitors to the sushi bar and other places where investigators discovered a radioactive trail.

But for unknown reasons, the British government refused to issue forensic reports, autopsy results and other investigation documents to the Russian side. Russia, in turn, concluded that England was interested in distorting the facts that would make it possible to tailor all events to the version they developed.

The Russian Federation conducted an investigation and ruled that D. Kovtun and A. Lugovoi were also injured, an attempted murder was recognized and traces of polonium-210 poisoning were discovered. A criminal case has been opened in the murder of Litvinenko, under suspicion of which, besides the British government, is seen the companion of A. Litvinenko from Italy, Mario Scaramella, with whom he met in the sushi bar of Itsu a few hours before meeting at Millennium. Litvinenko himself, already in the hospital, said that he felt unwell just after meeting with an Italian colleague. In Itsu, he handed him documents in the case of Anna Politkovskaya. Traces of polonium-210 were also found at Scaramella, in his hotel room and at other addresses of his presence.

After the incident, more than a thousand victims called the London Service hotline; more than a hundred revealed the content of polonium-210.

Why use polonium-210

Radioactive polonium is a silver-white metal, relatively soft, found in uranium ore. Unique in many respects, this element was first inscribed in the periodic table as radioactive. Located at number 84, it differs in that among those without stable isotopes this is the lightest element. Used in space research.

He was not known to the general public until he became the cause of scandalous deaths. Very rarely found in nature, to get it artificially, a nuclear reactor is needed. The list of countries that produce polonium-210 is very wide - it includes North Korea, Israel, and a number of other countries, including Russia.

The half-life of polonium-210 is 138 days and 9 hours, then it loses its radioactive properties. It is quickly oxidized in air, it cannot be picked up and breathed close. Thanks to alpha radiation over long distances, it is not dangerous and the damage is greatly reduced if the distance of the dangerous object exceeds 10 cm.

It is used when removing statistical electricity.as a heat source in space objects, for industrial purposes as a neutron source, as an experimental method for fighting cancer.

Polonium-210 was also found in tobacco leaves, which confirmed the detrimental importance of smoking for health. However, it has not yet been possible to remove the isotope from tobacco leaves.

Symptoms and treatment for polonium-210 poisoning

The production and manufacture of polonium in Russia and in other countries is strictly classified by the government and every milligram of metal mined is controlled. For this reason meeting polonium somewhere is quite difficult by accident, although for example in the USA there were attempts to use it in household utensils - for example, in the form of an antistatic brush, which does not stick dust. Safe packaging neutralizes the radioactive harm of the element, and the property of alpha particles in polonium acts as intended - in this case, ionize the air.

But if nevertheless there was contact with a deadly poison, such as polonium-210, you need to immediately seek medical help.

Without obvious signs, such poisoning provokes the development of radiation sickness with pronounced symptoms of a radioactive lesion. Damage received and symptoms are directly dependent on the dose of the element.

Like poisoning with other highly toxic metals, polonium-210 poisoning is manifested by the following symptoms:

• nausea, vomiting, diarrhea;
• tachycardia coupled with hypertension;
• fatigue, breakdown;
• impaired consciousness, delusional states;

In addition to the general symptoms, radiation sickness has a number of pronounced features that are externally manifested in hair loss, general sharp aging of the body and further failure of all organs, starting with the liver, as the first fighter for processing the drug, and the kidneys, as an instrument for its elimination. In the future, at a critical dose, the immune system and the leukocyte formula that is responsible for it are completely damaged. Hence, there may be additional signs of a lack of lymph and bone marrow.

Once in the body, polonium-210 is evenly distributed through the blood throughout all organs and tissues. Its almost uniform concentration can be seen within a few hours after poisoning. The metabolic processes of organs after contact with the poison are disturbed as well as the systems - circulatory, nervous, digestive, cardiac. The stool eventually becomes bloody, or its complete absence is possible. Disorders of the central nervous system can be the causes of convulsions, psychoses and delirium. The peripheral nervous system no longer provides motor motility, which leads to its disruption, as well as to terrible weakness. Violation of cardiac activity provokes seizures, the autonomic system - tachycardia and pressure. A person may also experience partial or complete blindness.

Treatment should be started as early as possible, since the longer the polonium stays in the body, the more likely it is to pass the “point of no return” and fatally harm organs. Polonium is very well absorbed in all organs and tissues, so infection is possible if you just touch the metal. Once inside, this isotope is absorbed into the tissue of organs in just a few minutes. When touched, immediately and abundantly wash the area of \u200b\u200bthe body that had contact with the isotope, laundry soap or laundry detergent.

If polonium enters the body through the esophagus, vomiting must be induced immediately. Since the count goes on for minutes and you can’t wait, doctors use apomorphine in the form of injections under the skin. Further, a laxative is needed - magnesium sulfate, sodium sulfate, enemas.

Polonium can be completely eliminated from the body with the help of the kidneys within 6-11 months, but during this time it can accumulate and cause harm - for example, partial or complete baldness.

If polonium is deeply absorbed into the tissue of the organs, then doctors use compounds based on drugs such as unitiol and oxathiol, which are able to “get” polonium-210 “from the depths” and bring it out. They are administered with a dropper in a hospital for a week. After such treatment, recovery comes.

Since polonium-210 is rather difficult to detect, and also because of the rarity of such poisonings, the issue has not been fully studied, which reduces the chances of a favorable prognosis. Therefore, in the treatment of such poisoning, the main stage is the early diagnosis of the disease, so that it is time to help the body until the deadly poison has damaged the organs too much.

Polonium-210 causes a very clear association with radiation. And this is not in vain, since it is extremely dangerous.

Discovery story

Its existence was predicted back in 1889 by Mendeleev, when he created his famous periodic table. In practice, this element number 84 was obtained nine years later by the efforts of the Curie spouses, who studied the phenomenon of radiation. I tried to find out the cause of the strong radiation emanating from certain minerals, and therefore I started working with several rock samples, treating them with all methods available to her, dividing them into fractions and discarding unnecessary ones. As a result, she received a new substance, which became an analog of bismuth and the third open radioactive element after uranium and thorium.

Despite the successful results of the experiment, Maria was in no hurry to talk about her find. conducted by a colleague of the Curie spouses, also did not give reason to talk about the discovery of a new element. Nevertheless, in a report at a meeting of the Paris Academy of Sciences in July 1898, the couple reported on the alleged receipt of a substance exhibiting the properties of the metal and proposed to call it polonium in honor of Poland, the birthplace of Mary. This was the first and only case in history when an element that has not yet been reliably identified has already been named. Well, the first sample appeared only in 1910.

Physical and chemical properties

Polonium is a relatively soft silver-white metal. It is so radioactive that it glows in the dark and constantly heats up. At the same time, its melting temperature is slightly higher than that of tin - only 254 degrees Celsius. The metal oxidizes very quickly in air. At low temperatures, forms a monatomic simple cubic crystal lattice.

By its chemical properties, polonium is very close to its analogue - tellurium. In addition, the high level of radiation has a great influence on the nature of its compounds. So reactions involving polonium can be very spectacular and interesting, albeit quite dangerous in terms of health benefits.

Isotopes

In total, science currently knows 27 (according to other sources - 33) forms of polonium. None of them are stable, and they are all radioactive. The heaviest of the isotopes (with ordinal numbers from 210 to 218) are found in small quantities in nature, the rest can only be obtained by artificial means.

Radioactive polonium-210 is the most long-lived of its natural forms. It is contained in a small amount in radium-uranium ores and is formed due to a chain of reactions starting with U-238 and lasting about 4.5 billion years, if we talk about the half-life.

Getting

1 ton contains the polonium-210 isotope in an amount equal to about 100 micrograms. They can be distinguished in the processing of production waste, however, to obtain a more or less significant volume of the element would have to process a huge amount of material. A much simpler and more efficient method is fusion using neutron irradiation of natural bismuth in nuclear reactors.

As a result, after some more procedures, polonium-210 is obtained. Isotopes 208 and 209 can also be obtained by irradiating bismuth or lead with accelerated beams of alpha particles, protons, or deuterons.

Radioactivity

Polonium-210, like other isotopes, is an alpha emitter. The heavier group also emits gamma rays. Despite the fact that the isotope 210 is the source of only alpha particles, it is quite dangerous, it can not be taken with your hands and even come close to a distance, because when it warms up, it goes into an aerosol state. Polonium ingestion with breathing or food is also extremely dangerous. That is why work with this substance takes place in special airtight boxes. Interestingly, this element was discovered in tobacco leaves about half a century ago. The decay period of polonium-210 compared with other isotopes is quite large, but because it can accumulate in the plant and subsequently harm the health of the smoker even more. However, any attempts to extract this substance from tobacco were unsuccessful.

Danger

Since polonium-210 emits only alpha particles, observing certain precautions, you should not be afraid of working with it. The path length of these waves rarely exceeds ten centimeters, in addition, they usually can not penetrate the skin.

However, once inside the body, they cause him great harm. When it enters the bloodstream, it quickly spreads to all tissues - after a few minutes, its presence can be seen in all organs. First of all, it is present in the kidneys and liver, but in general, it is distributed fairly evenly, which can explain its high overall damaging effect.

The toxicity of polonium is so great that even small doses cause chronic radiation sickness and death after 6-11 months. The main ways of excretion from the body are through the kidneys and gastrointestinal tract. Dependence on the method of hit. The elimination half-life makes from 30 to 50 days.

Accidental polonium poisoning is completely impossible. In order to obtain a sufficient amount of a substance, it is necessary to have access to a nuclear reactor and to intentionally insert an isotope to the victim. The complexity of the diagnosis also lies in the fact that only a few cases are known in history. The first victim is considered to be the daughter of the discoverers of polonium - Irene Joliot-Curie, who, during research, broke a capsule with a substance in the laboratory and died 10 years later. Two more cases are in the 21st century. The first of them is the sensational case of Litvinenko, who died in 2006, and the second is the death of Yasser Arafat, in whose things traces of a radioactive isotope were found. However, the final diagnosis has not been confirmed.

Decay

One of the most long-lived isotopes, along with 208 and 209, is polonium-210. (that is, the time during which the number of radioactive particles is halved) in the first two are 2.9 and 102 years, respectively, and the last 138 days and 9 hours. As for the remaining isotopes, their lifetime is calculated mainly in minutes and hours.

The combination of various properties of polonium-210 makes it the most convenient of a number for use in various fields of life. Being in a special metal shell, he can no longer harm health, but is able to give his energy for the benefit of mankind. So what is polonium 210 used for today?

Modern application

According to some reports, about 95% of polonium production is concentrated in Russia, with about 100 grams of the substance being synthesized per year, and almost all of it is exported to the United States.

There are several areas in which polonium-210 is used. First of all, these are spacecraft. With its compact size, it is indispensable as an excellent source of energy and heat. Although approximately every 5 months its efficiency is halved, heavier isotopes are much more expensive to produce.

In addition, polonium is completely indispensable in nuclear physics. It is widely used in studying the effect of alpha radiation on other substances.

Finally, another area of \u200b\u200bapplication is the manufacture of devices for removing static electricity for both industry and home use. It is even amazing how such a dangerous element can become almost a kitchen utensil, being enclosed in a reliable shell.

MOSCOW, Dec 11 - RIA News.  The discussion in the media around the properties of polonium-210, discovered in the body of ex-FSB officer Alexander Litvinenko, contains a lot of inaccurate information, which ultimately leads to "confusion", an expert in nuclear physics told RIA Novosti.

Litvinenko, who fled to the UK in 2000 and received a British passport in October of this year, died on November 23 at the University College London hospital. Specialists from the British Health Agency found traces of the radioactive element polonium-210 in his body.

Traces of polonium were found in the places Litvinenko visited, in particular, in a restaurant and hotel in central London.

“In such complex issues as the handling of a radioactive isotope and the consequences of a person’s defeat with polonium-210, unfortunately, very many consider themselves experts, inventing incredible things. In the beginning there appeared implausible information spread by the media that people poisoned by polonium-210 could leave after traces of themselves. This is nonsense, no perspiration can take polonium-210 out, "said the expert.

A similar opinion was expressed by RIA Novosti earlier director of the Institute for Strategic Stability of Rosatom Viktor Mikhailov. He stated that a person affected by polonium-210 "cannot leave traces of the isotope."

"What are the traces? This is ridiculous! A person struck by polonium-210 cannot leave traces after himself, unless he carried this polonium-210 in his hands," Mikhailov said.

According to him, "the polonium-210 isotope has alpha radiation and since it was inside a person, it cannot leave traces."

At the end of November, the UK Health Agency issued an official statement stating that "the risk of infection with this substance (polonium-210) is minimal."

“The risk of radiation sickness appears only if this substance has penetrated: you inhaled it, put it in your mouth or it fell into an open wound. It does not constitute a threat as long as it remains outside. Most of the traces of the substance can be removed simply by washing your hands using a washing machine or dishwasher, "- said in a statement by the British agency.

According to an expert in the field of radiation medicine, the development of radiation sickness from the ingress of polonium-210 into the human body is almost inevitable. “But it all depends on the dose of the isotope and on the characteristics of the victim’s body. If the dose is extremely small, then the presence of polonium-210 can be recorded, but the risk to health will be minimal,” an expert at RIA Novosti said.

Another expert in the field of nuclear physics recalled that "element 84 - polonium is the first element inscribed in the periodic table after the discovery of radioactivity." "He is the first in order of atomic numbers and the lightest of the elements that do not have stable isotopes," he said.

Polonius was discovered by Pierre and Marie Curie and got its name on July 13, 1898 in honor of the historical homeland of Mary - Poland. It is found in nature, but in uranium ores its concentration is 100 trillion times less than the concentration of uranium.

Polonium is a soft silver-white metal that is slightly lighter than lead. It enters the human body with food and tobacco smoke.

Isotopes are varieties of the same radioactive element. For example, polonium exists in variants such as polonium (P) P-210 with a half-life of 138 days, P-208 - with a half-life of two years, and P-209 - with a half-life of 103 years. According to the expert, the most important from the point of view of science is the polonium-210 isotope - a pure alpha emitter.

"The alpha particles emitted by him are inhibited in the metal and, running through it just a few micrometers, they waste their atomic energy, which turns into heat, which, in turn, can be used for heating or converted into electricity," said the expert.

This energy is already being used both on Earth and in space. The P-210 isotope is used in power plants of some artificial satellites. In particular, he flew beyond the Earth on the Soviet satellites Cosmos-84 and Cosmos-90.

Pure alpha emitters - and polonium-210 - have several obvious advantages over other radiation sources, including the fact that such emitters practically do not require special protective measures: the penetrating power and the mean free path of alpha particles are minimal. At one time, the radioactive isotope polonium-210 served as the fuel of the “stove” installed on the “Lunokhod-2”.

Similar devices are used on Earth. In addition to them, polonium-beryllium and polonium-boron neutron sources are important. These are sealed metal ampoules in which a polonium-210 coated ceramic tablet is made of boron carbide or beryllium carbide. The neutron flux from the nucleus of a boron or beryllium atom gives rise to alpha particles emitted by polonium.

Such neutron sources are light and portable, completely safe in operation, and very reliable. A brass ampoule with a diameter of 2 cm and a height of 4 cm - the Soviet polonium-beryllium source of neutrons - gives up to 90 million neutrons every second.

Among other earthly matters, polonium should be mentioned in its use in standard electrode alloys, which are needed for spark plugs of internal combustion engines. Alpha particles emitted by polonium-210 reduce the voltage required to form a spark and make it easier to turn on the engine.

An expert in the field of radiation medicine said that despite the presence of only alpha radiation from the P-210, which “can in principle be protected with a simple barrier”, they work with polonium only in airtight boxes, since it is one of the most dangerous radio elements.

The expert noted that today with a high degree of probability we can say that Litvinenko died of acute radiation sickness.

"There are many questions in the history of his death, and every day there are more and more of them, but it is clear that the data we know through the official statements of the British authorities on the course of Litvinenko’s disease and the causes of his death most likely indicate a radiation injury disease, "he said.

"Although, of course, it is impossible to give an absolutely accurate answer without disclosing the official results of the autopsy," the expert emphasized.

He said that it is possible to talk about acute radiation damage to the human body when receiving a radiation dose of more than 0.5 sievert (Sv).

Sievert is a unit of measure for effective and equivalent dose. The most frequently used fractional unit of a sievert is its thousandth share - millisievert.

1 Sievert is equal to 1000 millisieverts (mSv). Equivalent dose - the absorbed dose in an organ or tissue, multiplied by the corresponding weight coefficient for a given type of radiation. The biological effectiveness of various types of ionizing radiation is taken into account, since at the same absorbed dose, alpha, beta and gamma radiation have a different effect.

A non-systemic unit of equivalent dose is rem - the biological equivalent of X-ray. 1 Sv is equal to 100 rem.

"Negative effects appear immediately or after a few days, in particular, the immune system weakens, the gastrointestinal tract, lungs and other internal organs, as well as the central nervous system," the expert said.

At doses from 1 to 2 sievert, radiologists believe that a fifth of the victims can be fatal. At doses above 7 sievert, the percentage of survivors is zero.

As previously reported in some media, in Russia at the Ural Mayak plant there is a reactor, where at one time special targets were irradiated from bismuth to obtain intermediate raw materials from which pure polonium-210 was isolated.

According to RIA Novosti in Rosatom, two years ago the reactor, which was used to produce polonium-210, was decommissioned.

Some British media reported that polonium, which Litvinenko could have been poisoned in London, was produced in the city of Zheleznogorsk, Krasnoyarsk Territory. This information was called into question by the ex-head of the Minatom of the Russian Federation, Viktor Mikhailov, who noted that British experts could not so quickly determine the place of manufacture of polonium-210.

"I think that it is impossible so quickly from the moment of detecting traces of polonium-210, without exchanging information with countries that can produce polonium, to determine the place of production of this radioactive isotope," Mikhailov said.

Krasnoyarsk nuclear experts also completely rejected the suggestion that polonium-210 discovered in the UK could have been produced in the Krasnoyarsk Territory.

According to the directorate of the mining and chemical plant operating in the closed city of Zheleznogorsk, which has been producing weapons-grade plutonium for almost half a century, the isotope called "has never been present in the technological chains of local enterprises."

Earlier, the head of Rosatom, Sergei Kiriyenko, said at a press conference that Russia monthly exports polonium-210 to the United States, supplying under strict control.

The US Nuclear Regulatory Commission, in turn, stated that polonium-210 samples available on the US market are not dangerous. According to commission spokesman David MacIntyre, the dangers are not posed by the educational and scientific samples of the polonium-210 isotope freely sold through the Internet, or technical devices and devices for combating static electricity sold through the retail trade that contain this radioactive element.

"If you want to disassemble the device, any amount of it (polonium-210) will be difficult to extract and it will still be in harmless form," said MacIntyre, emphasizing that anti-static devices sold on the US market can be an "extremely unlikely source." radioactive polonium-210 so that it can be used to poison a person.

The American company United Nuclear issued a statement in which it said that the volume of polonium-210 in its samples is so small that about 15 thousand such samples will need to be purchased to accumulate a lethal dose of this radioactive isotope. At a price of $ 69 per sample, the total cost of such a purchase would be more than $ 1 million, which, of course, would immediately cause concern both because of the huge amount and because of the large number of orders for a company that usually sells no more than one two samples per quarter.

At the same time, Michael Levy, an expert on science and technology at the Political Science Council on Foreign Relations, who was contacted by ABC for comments, does not consider extracting polonium-210 from commercially available samples and devices in the USA to be such a difficult task. With basic chemical knowledge and free-selling equipment worth a couple of hundred dollars, polonium-210 can be extracted, given the fact that "sellers show engineering diagrams of their devices on the Internet," he said.

At the same time, Levy questioned the allegations that appeared in the British and American media that polonium-210 can be obtained only in the most sophisticated laboratories operating in nuclear complexes. "The idea that you have to have access to the Russian nuclear complex for this is stupid," said Levy, who agrees with those experts who are surprised at the choice of polonium-210 as a poison for killing people.

"There are undoubtedly more proven and reliable ways to kill people. Don’t be so afraid of polonium, because there are many other ways to kill people by imperceptibly sprinkling something in a drink," said Levy.

Chairman of the Federation Council Committee on Defense and Security Viktor Ozerov, in turn, rejected all charges against the Russian special services, which supposedly could have been implicated in the death of Litvinenko.

"I doubt that our intelligence services are so unprofessional as to spread the poison into twenty London offices and endanger the lives of ordinary people," he said.

Chemistry

Element N ° 84 - polonium - the first element inscribed in the periodic table after the discovery of radioactivity. He is the first (in the order of atomic numbers) and the lightest of the elements that do not have stable isotopes. He is one of the first radioactive elements used in space research.

At the same time, element number 84 is perhaps one of the least known, least popular radioactive elements. At first, he remained in the shadows, pushed into the background by the glory of radium. Later it was not advertised too much, like almost all materials of atomic and space research.

The history of the discovery of element number 84 is well known. It was opened by Pierre Curie and Maria Sklodowska-Curie. In the Curie spouses' laboratory journal, the symbol “Ro” (inscribed by Pierre’s hand) first appears on July 13, 1898.

A few years after the death of Pierre Curie, his wife and co-author of two of his most striking discoveries wrote the book Pierre Curie. Thanks to this book, we will first-hand learn the history of the discovery of polonium and radium, get acquainted with the features and principles of the work of two prominent scientists. Here is an excerpt from this book: “... The ore we chose was tar blended, uranium ore, which in its pure form is about four times more active than uranium oxide ... The method we used is a new chemical analysis method based on radioactivity. It consists in the separation by conventional means of chemical analysis and in the measurement, under appropriate conditions, of the radioactivity of all the isolated products. In this way, you can imagine the chemical properties of the desired radioactive element; the latter is concentrated in those fractions whose radioactivity becomes more and more as the separation continues. Soon we were able to determine that radioactivity is concentrated mainly in two different chemical fractions, and we came to the conclusion that at least two new radioelements are present in the resin blende: polonium  and radium. We reported on the existence of the polonium element in July 1898 and about radium in December of that year ... "

  The first polonium report is dated July 18th. It is written in the highest degree restrained and correct. There is such a phrase there: "If the existence of this new metal is confirmed, we suggest calling it polonium, after the name of the homeland of one of us."

In Latin, Polonia - Poland.

“Polonium” is not the first “geographical” name of an element. By that time, Germany and ruthenium, and gallium, and scandium had already been discovered. Nevertheless, this name is special, it can be considered as a protest name: at that time there was no independent Polish state. Poland was fragmented, divided between the Austrian, German and Russian empires ...

In the famous book "Marie Curie", written by the youngest daughter of the spouses Curie Eva, the following conclusion was made:

“The choice of this name shows that Marie, becoming a French physicist, did not renounce her homeland. This is also evidenced by the fact that before the article “On a new radioactive substance in uraninite” appeared in the “Reports of the Academy of Sciences”, Marie sent the manuscript to her homeland, to Joseph Bogussky, the head of the laboratory of the Museum of Industry and Agriculture, where they started her first scientific experiments. The message was published in Swiatlo, a monthly illustrated review, almost simultaneously with the publication in Paris. "
  In the Polish People’s Republic, the memory of Maria Skłodowska-Curie is sacredly honored.

The house in which she was born was restored, the Warsaw Radium Institute is named after her.

  Why radium and not polonium?

In fact, why radium, not polonium, brought the Curie spouses worldwide fame? After all, the first element they discovered was element 84. After a year of work, they had no doubt that there were two new elements in the uranium tar. But these elements made themselves known only by radioactivity, and in order to convince everyone, and especially chemists, that the discoveries really happened, it was necessary to isolate these activities, to obtain new elements, at least in the form of individual compounds.

All radioactive elements and isotopes, as you know, are now united in families: decaying, the nucleus of a radioactive atom turns into the atomic nucleus of another, daughter element. All elements of the radioactive families are in a certain equilibrium among themselves. It was measured that in uranium ores the equilibrium ratio of uranium to polonium is 1.9-1010, and 0.2 mg of polonium are in equilibrium with a gram of radium. This means that in uranium minerals, radium is almost 4 million times less than uranium, and polonium is another 5 thousand times less.

The Curie spouses, of course, did not know these exact numbers. Nevertheless, realizing what a titanic work to highlight new elements to be, they made the only right decision. The book we have already quoted about Pierre Curie says: “The results obtained after a year of work have clearly shown that radium is easier to isolate than polonium; therefore, efforts were concentrated on radium. ”

Artificial polonium

The question is quite appropriate here: if polonium is really an ultra-rare and ultra-hard-to-reach element, then what is the cost of polonium mining in our time? We do not have exact numbers, but today element 84 is no less accessible than radium. It is really difficult to get it from ore, but there is another way - nuclear fusion.

Today, polonium is obtained in two ways, with bismuth-209 as the feedstock in both cases. In atomic reactors it is irradiated with neutron fluxes, and then the relatively important isotope of element 84, polonium-210, is formed along a relatively simple chain of nuclear transformations:

209 83 Bi + 1 1 p -γ → 210 83 Bi-β → 210 84 Po.
  And if the same bismuth isotope is placed in another important nuclear fusion machine - the cyclotron, and there it is bombarded with proton fluxes, then by the reaction

209 83 Bi + 1 0 n -γ → 209 84 Po + 1 0 n.

the longest-lived isotope of element N ° 84 is formed.

The first reaction is more important: polonium-210 is a much more interesting isotope for technology than polonium-209. (For reasons, see below.) In addition, in the second reaction, lead-209 is formed simultaneously with polonium — one of the most difficult to remove polonium impurities.

In general, the purification of polonium and its isolation from a mixture with other metals for modern technology does not present a particularly difficult task. There are different ways of isolating polonium, in particular electrochemical, when metallic polonium is isolated at a platinum or gold cathode, and then separated by sublimation.

Polonium is a low-melting and relatively low-boiling metal; its melting and boiling points are 254 and 962 ° C, respectively.

  Chemistry basics

It is quite obvious that the current perfect methods for obtaining and isolating polonium became possible only after a thorough study of this rare radioactive metal. And its compounds, of course. The fundamentals of polonium chemistry were laid by its discoverers. In one of the laboratory notebooks of the Curie spouses, there is a record made in 1898: “After the first treatment of the resin blende with sulfuric acid, polonium is not completely precipitated and can be partially extracted by washing with diluted SO 4 H 2 (the chemical indexation of the original is saved here and below). In contrast, two treatments of the resin blende residue and one treatment of the German [ore] residue with carbonates produce carbonates, and SO 4 H 2 completely precipitates the active substance from the carbonate dissolved in acetic acid. ”

Later, they learned much more about this element. They learned, in particular, that elemental polonium - a silver-white metal - exists in two allotropic modifications. The crystals of one of them - low temperature - have a cubic lattice, and the other - high temperature - rhombic.

A phase transition from one form to another occurs at 36 ° C; however, at room temperature, polonium is in a high temperature form. It is heated by its own radioactive radiation. In appearance, polonium is similar to any ordinary metal. By fusibility - on lead and bismuth. By electrochemical properties - on noble metals. According to the optical and x-ray spectra - only for himself. And according to the behavior in solutions - all other radioactive elements: due to ionizing radiation in solutions containing polonium, ozone and hydrogen peroxide are constantly formed and decomposed.

By its chemical properties, polonium is a direct analogue of sulfur, selenium, and tellurium. It exhibits valencies 2-, 2+, 4+ and 6+, which is natural for an element of this group. Numerous polonium compounds are known and fairly well studied, ranging from simple PoO 2 oxide, soluble in water, and ending with complex complex compounds. The latter should not be surprising. The tendency to complexation is the fate of most heavy metals, and polonium is one of them. By the way, its density - 9.4 g / cm 3 - is slightly less than that of lead.

A very important study of the properties of polonium for radiochemistry as a whole was carried out in 1925-1928. at the Leningrad Radium Institute. It was fundamentally important to find out whether radioactive elements in solutions in vanishingly small quantities can form their own colloidal compounds. The answer to this question - the answer is positive - was given in the work "On the question of the colloidal properties of polonium." Its author was I.E. The old man, later a well-known radiochemist, is a corresponding member of the USSR Academy of Sciences.

  Polonium on Earth and in space

To people far from radiochemistry and nuclear physics, the following statement will seem strange: today polonium is a much more important element than radium. The historical merits of the latter are indisputable, but this is the past. Polonium is an element of today and tomorrow. First of all, this refers to the polonium-210 isotope.

In total, 27 polonium isotopes with mass numbers from 192 to 218 are known. This is one of the most multi-isotopic, so to speak, elements. The half-life of the longest-lived isotope is polonium-209-102. Therefore, naturally, in the earth's crust there is only radiogenic polonium, and it is extremely small there - 2-10 * 14%. Several polonium isotopes existing in nature have their own names and symbols that determine the place of these isotopes in the radioactive series. So, polonium-210 is also called radium F (RaF), 211 Po - AcC, 2I2 Po - ThC, 214 Po - PaC, 215 Po - AcA, 216 Po - ThA and 218 Po - RaA.

Each of these names has its own history, all of them are associated with the “parent” isotopes of that or another atomic variety of polonium, so it would be more correct to call them not “names”, but “middle names”. With the advent of the modern isotope naming system, the old names listed almost gradually went out of use.

The most important polonium-210 isotope is a pure alpha emitter. The particles emitted by it are braked in the metal and, running through it just a few micrometers, they waste their energy. Atomic energy, by the way. But energy does not appear and does not disappear. The energy of alpha particles of polonium is converted into heat, which can be used, say, for heating and which is not so difficult to turn into electricity.

This energy is already being used both on Earth and in space. The 210 Po isotope is used in the power plants of some artificial satellites. In particular, he flew off the Earth using the Soviet Cosmos-84 and Cosmos-90 satellites.

Pure alpha emitters, and polonium-210 in the first place, have several obvious advantages over other radiation sources. Firstly, the alpha particle is quite massive and carries a lot of energy. Secondly, such emitters practically do not require special protective measures: the penetrating power and the mean free path of alpha particles are minimal. There are thirdly, fourthly, and fifthly, but these two advantages are the main ones.

In principle, plutonium-238, polonium-210, strontium-90, cerium-144 and curium-244 are acceptable sources of energy for working at space stations. But polonium-210 has an important advantage over other competing isotopes - the highest specific power, 1210 W / cm 3. It releases so much thermal energy that this heat can melt the sample. To prevent this, polonium is placed in a lead matrix. The resulting alloy of polonium and lead has a melting point of about 600 ° C - much more than each of the constituent metals. Power, however, is reduced, but it remains quite large - about 150 W / cm 3.

W. Corliss and D. Harvey, authors of the book “Sources of Energy from Radioactive Isotopes” write: “As recent studies show, 210 Po can be used in manned spacecraft.” As another advantage of polonium-210, they mention the availability of this isotope. The same book says that bismuth and polonium obtained from it are easily separated by ion exchange. So the space service polonium, apparently, is just beginning.

A good start has been made. The radioactive isotope polonium-210 served as the fuel of the “stove” installed on the “Lunokhod-2”. The nights on the moon are very long and cold. For 14.5 Earth days, the lunar rover was at a temperature below - 130 ° C. But in the instrument container all this time the temperature acceptable for complex scientific equipment had to be kept.

A polonium heat source was placed outside the instrument container. Polonium radiated heat continuously; but only when the temperature in the instrument compartment fell below the required limit, the heat carrier gas heated by polonium began to flow into the container. The rest of the time, excess heat was dissipated into outer space. The Lunokhod-2 nuclear stove was characterized by complete autonomy and absolute reliability. True, polonium-210 also has a limitation. The relatively short half-life of 138 days only puts a natural limit on the life of polynonium radioactive sources.

Similar devices are used on Earth. In addition to them, polonium-beryllium and polonium-boron neutron sources are important. These are sealed metal ampoules in which a polonium-210 coated ceramic tablet is made of boron carbide or beryllium carbide. The neutron flux from the nucleus of a boron or beryllium atom gives rise to alpha particles emitted by polonium.

Such neutron sources are light and portable, relatively safe in operation, and very reliable. A brass ampoule with a diameter of 2 cm and a height of 4 cm - the Soviet polonium-beryllium source of neutrons - gives up to 90 million neutrons every second.

Among other earthly affairs of element 84, its use in standard electrode alloys is probably worth mentioning. These alloys are needed for spark plugs of internal combustion engines. Alpha particles emitted by polonium-210 reduce the voltage required to form a spark, and therefore facilitate starting the engine.

Safety precautions

When working with polonium, special care must be taken. Perhaps this is one of the most dangerous radio elements. Its activity is so great that, although it emits only alpha particles, you can’t take it with your hands, the result will be radiation damage to the skin and, possibly, the whole organism: polonium penetrates quite easily through the skin. Element No. 84 is also dangerous at a distance exceeding the mean free path of alpha particles. It is able to quickly become aerosolized and infect air. Therefore, they work with polonium only in airtight boxes, and the fact that it is not difficult to protect oneself from radiation of polonium is extremely favorable for everyone who is dealing with this element.

An attentive reader probably already noticed that in this article wherever practical polonium is used, only one isotope appears - with a mass number of 210. Indeed, other isotopes of element 84, including the longest-living of them, polonium, 209, so far used only for research purposes, to study and refine the nuclear-physical characteristics of these isotopes. These isotopes have not yet been put to practical use.

True, many scientists believe that polonium-208, also a pure alpha emitter, is also promising for space energy sources. The half-life of it is significantly longer than that of polonium-210, - 2.9 years. But while this isotope is almost inaccessible. How much time to go to him only in perspective, the future will show.