Little was known about radioactive polonium until it was reported that former spy Alexander Litvinenko was murdered. Even after we graduated as engineers, we could only vaguely remember that polonium was discovered by Pierre and Marie Curie.
The polonium atom was discovered by husband and wife Pierre and Marie Curie in 1898. At that time, Marie Curie was just a schoolgirl collaborating with her husband, a famous scientist. The incident of polonium, which was randomly identified, deserves to be symbolized as an example for graduate students.
In 1896, a year after Pierre and Marie Curie were married, William Röntgen discovered X-rays and Henri Becquerel found that uranium was naturally radioactive. Hearing this news, Marie decided to choose radioactivity as a research topic. At that time, there was no artificial radioactive source, so Pierre and Marie Curie had to extract uranium from pitchblende ore. After extracting all the uranium from the pitchblende ore, the couple noticed that there was still some radioactive material left. They further analyzed pitchblende ore and discovered that the polonium atom was 400 times more active than uranium. In memory of Marie Curie’s native country, Poland, the new atom was named polonium . After extracting all the polonium, Pierre and Marie Curie discovered another atom, the radium atom , which is more active than the polonium atom, 900 times stronger than uranium.
Polonium is a very rare atom.
It is false to say that Pierre and Marie Curie were lucky enough to discover polonium and radium by chance. No scientific discovery is the result of random chance.
In order to obtain the uranium atoms for which radioactivity studies were carried out, schoolgirl Marie Curie had to extract uranium from pitchblende ore. This is a very hard job. She processed tons of pitchbende to extract several pounds of uranium. Seeing Marie work so hard, Pierre had to help his new wife’s hand. Once there was enough uranium to begin research on radioactivity, Pierre and Marie could dismiss the remark that “something” was still emitting in the ore. But because they wanted to find out what “something” was, the couple discovered polonium and then radium. Through her diligence and will to learn, not by chance, in 1903 Marie Curie became the first woman to hold a doctorate in the history of French universities and the first, both male and female. women, received two Nobel Prizes.
Polonium is an atom so rare that it cannot be detected with the most sensitive meters. There is less than 100 micrograms in a ton of pitchblende ore. To get enough polonium to meet the needs of the nuclear industry, more polonium must be produced in two ways.
Natural polonium arises from the uranium decay series . Of the atoms in the Mendelev table, polonium has the most isotopes: 25. Those isotopes have been identified from Po 194 to Po 218. But only the density of the polonium isotope Po 210 is significant ii. All of these polonium isotopes are alpha emitting which means spontaneously ejecting a helium ion.
At room temperature, polonium is in the alpha form, that is, atoms arranged in cubic crystals. This is the only case where a solid has a cubic crystalline form without nesting. At temperatures above 38°C, the crystal turns rhombic.
Polonium Po 210 has a half-life of 138 days, meaning that the activity is halved after 138 days. On decay, polonium Po 210 turns into lead isotope Pb 206, a stable isotope that does not emit radiation. Each alpha particle emitted from that decay has an energy of 5.407 MeV iii. This is a very high power that makes the activity of one gram of polonium up to 140 watts. That power is so strong that a polonium is always hot and the surrounding trachea is stimulated causing a blue aura.
By being able to heat surrounding materials, polonium is used as a heat source to keep components of spacecraft and artificial satellites warm. The radiation of polonium can heat a thermoelectric metal and generate electricity. Using that property, polonium has been used as a battery to generate electricity for spacecraft, artificial satellites. Once upon a time there were pacemakers that ran on polonium batteries.
When polonium is mixed with beryllium, the alpha particles emitted by polonium break the beryllium nucleus and produce neutrons. This property was used as a source of neutrons to cause the first fission reactions for nuclear reactors. This property is also used to ignite atomic bombs.
In the past it was intended to use the electrostatic properties of polonium to mix with additives for many applications such as paints, bristles, etc. But because polonium is very toxic, these applications have been banned.
Like all radioactive substances, polonium is very dangerous to human health. Because of its high radioactivity, it is very toxic to allow polonium to enter the body. If absorbed into the body polonium will emit alpha thereby causing leukemia or other cancers. By comparison, by the same weight, polonium is a million times more toxic than hydrogen cyanide, the substance commonly used to poison people. Another reason polonium is particularly dangerous is that its biological half-life is quite long, about 50 days iv.
But it must also be said that polonium mainly emits alpha rays, which are blocked by a few centimeters of air. Therefore, if you do not get close to a polonium source, you will not be exposed to radiation. The risk of accidentally absorbing radioactive polonium is virtually nonexistent. Polonium does not diffuse across the skin membrane. So polonium can only enter the body through breathing or eating. But, as written above, polonium is very rare in nature. As for artificial polonium, the nuclear industry produces only about 100 grams a year, enough to power newly built nuclear reactors. With that amount, the probability of absorbing the artificial polonium emitted into the open air is really negligible.
The natural source of polonium’s risk is tobacco. People use phosphate fertilizers to fertilize plants. Phosphate ore with traces of uranium. Uranium decays into radon. When fertilizing plants with phosphate fertilizers, the plants absorb radon atoms. Radon decays to polonium. This is not harmful because, as mentioned above, natural polonium content is negligible and the body will quickly expel this substance after we eat vegetables. But when smoking, the heat is inhaled into the body. The heat causes the radon and polonium atoms to separate from the tobacco leaf, leading them into the body to allow them to attach to the throat and lungs. After that, they will no longer leave the body and continuously emit radiation. Although the amount of polonium inhaled is very small, smoking for a long time also accumulates enough to cause cancer. According to American doctors, it is the cause of 90 percent of cancers in smokers.
As far as we know, in the history of radioactivity, there are two scientists who were accidentally absorbed by polonium. They are Dr. Irene Joliot Curie, daughter of Pierre and Marie Curie, wife and collaborator of Frederic Joliot Curie, and professor Dror Sadeh, of the Weizmann Institute. In the late 50s of the last century, it seems that a Japanese doctor intentionally took a dose of polonium to commit suicide or experiment on himself with the effects of radiation. The assassination of Alexander Litvinenko was the first known radioactive murder. I don’t understand why the killer chose this ritual.