What is Polonium?
It is an element with the chemical symbol Po and atomic number 84 in the periodic table. Polonium is in Group 16 and period 6 in the periodic table of elements. It is a rare natural element and highly radioactive metal with no stable isotopes, It was discovered in 1898 by Marie Sklodowska Curie and Pierre Curie. It is extremely toxic even in small amounts and is termed as perfect poison.
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Properties of Polonium
Certain Facts About Polonium
Its chemical property is similar to bismuth and tellurium. (Polonium is the heaviest metal of the chalcogens, also known as the "oxygen family.")
It has no stable isotopes. (Po-210 has a half-life of only 138 days).
It is a radioactive semi-metal found in uranium ores. It is used in some devices to eliminate static electricity in processes such as manufacturing sheet plastic, rolling paper, etc.
manufacturing sheet plastics, and spinning synthetic fibers.
It emits alpha-particles after the disintegration.
It is classified as a metal because polonium electrical conductivity decreases as its temperature increases.
If polonium-210 enters inside the body, through inhalation or swallowing, the results can be fatal.
Tobacco smokers have more polonium-210 content compared to nonsmokers because smoking causes it to accumulates in the lungs.
Did You Know?
Uranium and thorium were the only known radioactive elements before Polish-French physicist, Marie Curie discovered polonium in the year 1898. Curie named polonium after her homeland, Poland. Poland was not an independent country at that time and was ruled by German, Russian, and Austro-Hungarian partition. With the hope of naming the element after her native land Madam Curie did so to publicize its lack of independence, Polonium was the first-ever element to be named highlighting a political controversy.
FAQs on Polonium
1. What is Polonium and what is the origin of its name?
Polonium (Po) is a rare and highly radioactive chemical element with the atomic number 84. It is classified as a metalloid and belongs to Group 16 of the periodic table. Discovered in 1898 by Marie and Pierre Curie, it was named after Marie Curie's native country, Poland (Latin: Polonia).
2. What are the key chemical and physical properties of Polonium?
Polonium has several distinct properties that are important for students to know:
- Appearance: It is a silvery-grey, solid metalloid at room temperature.
- Radioactivity: All isotopes of Polonium are radioactive. The most significant isotope, Polonium-210, is a powerful alpha emitter.
- Heat Generation: Its intense radioactivity generates significant heat, causing it to reach temperatures above 500°C and glow with a bluish light in the dark.
- Metallic Character: Following periodic trends, it has a more pronounced metallic character than other elements higher up in Group 16, such as sulphur or selenium.
3. Where is Polonium found, and how is it produced for commercial use?
Polonium occurs naturally only in very small amounts within uranium ores, as it is a product of uranium's radioactive decay chain. For practical applications, it is produced artificially in a nuclear reactor. The most common method involves bombarding the stable isotope of bismuth, Bismuth-209 (²⁰⁹Bi), with neutrons. This nuclear reaction converts bismuth into Polonium-210 (²¹⁰Po).
4. How does Polonium's radioactivity affect the human body if ingested or inhaled?
Polonium is extremely toxic to the human body. If it enters the body, the alpha particles emitted by Polonium-210 cause severe, localised damage to internal tissues and organs. This radiological poisoning disrupts cellular function and damages DNA, leading to radiation sickness. Symptoms include damage to the bone marrow, the gastrointestinal system, and other vital organs, which can be fatal even from microgram quantities.
5. Why is Polonium's alpha emission particularly useful for certain technological applications?
Polonium-210 is an almost pure alpha particle emitter. Alpha particles have a very short range and release all their energy upon impact, which makes them a highly concentrated and containable energy source. This property is exploited in two main ways:
- Thermoelectric Generators: It serves as a lightweight heat source to generate electricity for satellites, lunar rovers, and other unmanned space probes.
- Static Eliminators: In industrial processes like manufacturing paper or textiles, the alpha particles ionise the surrounding air, which neutralises static electricity and prevents dust attraction or sparks.
6. How do the properties of Polonium compare to other elements in Group 16, such as Oxygen and Sulphur?
As per the trends in the CBSE syllabus for p-Block elements, Polonium's properties differ significantly from lighter elements in Group 16. Compared to non-metals like Oxygen (a gas) and Sulphur (a solid), Polonium exhibits:
- Increased Metallic Character: It is a metalloid, showcasing the trend of increasing metallic nature down a group.
- Lower Ionisation Enthalpy: It requires less energy to remove an electron from Polonium.
- Lower Electronegativity: It has a weaker ability to attract bonding electrons.
- Inherent Radioactivity: Unlike the lighter, stable elements in the group, all of Polonium's isotopes are radioactive.
7. How does the danger of Polonium-210 compare to a chemical poison like hydrogen cyanide (HCN)?
Both substances are extremely lethal but operate through different mechanisms. Hydrogen cyanide is an acute chemical poison that acts almost instantly by blocking cellular respiration. In contrast, Polonium-210 is a radiological poison. Its danger comes from the sustained internal damage caused by alpha radiation over several days or weeks, leading to a fatal condition. On a weight-for-weight basis, Polonium-210 is considered significantly more toxic than cyanide.
