Introduction
Polonium is a metalloid present in group number 16 of the periodic table.
- The atomic number of polonium is 84 whereas its atomic mass is 209.
- Polonium has 84 electrons in its single atom.
- It has 84 protons and 125 neutrons in its nucleus.
- Polonium is represented by the symbol “Po”.
Naming and History
Polonium got its name after the name of the country Poland. This was due to the fact that polonium was discovered by Marie Curie and Poland was his native country.
- Mendeleev
Mendeleev predicted that there might be an element that followed bismuth and he predicted his atomic weight around 212.
- Marie Curie
In 1898, Marie Curie and his husband Pierre Curie, while working on radioactivity discovered the element polonium. They extracted some from pitchblende – the uranium oxide U3 O8 while investigating it.
Occurrence of Polonium
Polonium is rarely found in nature. It is present in uranium ores and some amounts can be obtained from uranium oxide. But generally, it is not obtained from ores.
Usually, polonium is obtained by bombarding bismuth- 209 in nuclear reactors with neutrons. Bismuth- 210 is produced which has a half-life of 5 days and decays into polonium through beta decay. Polonium- 210 is a strong alpha-emitter.
Properties of Polonium
Polonium is a radioactive, low melting, silvery-greyish metalloid which is rarely present in nature. It readily reacts and dissolves in dilute acids but slightly reacts and is soluble in alkalis. Polonium is volatile, half of its sample can evaporate within three days.
That is why it is kept in a sealed container. The melting point of polonium is 254°C and its boiling point is 962°C. Polonium has a density of 9.32 grams per cubic centimeter. It exists as solid at room temperature.
Polonium in Biological Systems
There is no known significant role of polonium in living organisms. But due to its radio activeness, it is highly toxic. Polonium- 210 is present in the smoke of cigarettes and can itself cause cancer.
Uses of Polonium
- Polonium- 210 is an alpha emitter so used as the source of the alpha particles in nuclear reactors.
- Polonium emits and neutralizes electrical charges so used in antistatic devices.
- Once it was used in textile mills to remove static charges.
- It is used in photographic plates to remove accumulated dust (static charges).
- Polonium is used for research and study purposes.
- On alloying with beryllium, it can be used as a portable source of neutrons.
- It can be used as the source of atomic heat, but due to the fact that it has a short half-life cannot be used in long-term processes.
- Polonium- 210 is a lightweight thermoelectric power source for space crafts.
Isotopes of Polonium
There are 29 known isotopes of polonium whose mass number ranging from 190 to 218. There are no stable isotopes. Polonium- 210 has a half-life of 138.9 days. The mush stable is Polonium- 209 with a half-life of 102 years and was discovered by Marie Curie.
MCQs
- What is the atomic number of polonium?
- A) 84
- B) 16
- C) 209
- D) 125 Answer: A) 84
- Who discovered the element polonium?
- A) Dmitri Mendeleev
- B) Marie Curie
- C) Antoine Lavoisier
- D) Isaac Newton Answer: B) Marie Curie
- Why is polonium named after Poland?
- A) It was discovered by a Polish scientist
- B) It is abundantly found in Poland
- C) Poland was the first country to synthesize it
- D) It was named in honor of the Polish government Answer: A) It was discovered by a Polish scientist
- How is polonium-210 primarily obtained?
- A) From natural occurrences in uranium ores
- B) By bombarding bismuth-209 with neutrons in nuclear reactors
- C) Through chemical extraction from lead deposits
- D) By electrolysis of water containing polonium ions Answer: B) By bombarding bismuth-209 with neutrons in nuclear reactors
- Which property of polonium makes it highly toxic?
- A) High melting point
- B) Volatility
- C) Insolubility in acids
- D) Low radioactivity Answer: B) Volatility
- What is the half-life of polonium-210?
- A) 5 days
- B) 138.9 days
- C) 102 years
- D) It has no half-life Answer: A) 5 days
- What role does polonium play in living organisms?
- A) Essential nutrient
- B) Significant metabolic function
- C) No known role
- D) Critical for cellular respiration Answer: C) No known role
- Which industry once used polonium to remove static charges?
- A) Aerospace
- B) Textile
- C) Electronics
- D) Pharmaceutical Answer: B) Textile
- What is the primary use of polonium-210 in nuclear reactors?
- A) Generating electricity
- B) Shielding radioactive materials
- C) Producing alpha particles
- D) Cooling reactor cores Answer: C) Producing alpha particles
- Which is the most stable isotope of polonium?
- A) Polonium-210
- B) Polonium-209
- C) Polonium-190
- D) Polonium-218 Answer: B) Polonium-209
- How does polonium react with dilute acids?
- A) It readily reacts and dissolves
- B) It slightly reacts and dissolves
- C) It remains inert
- D) It decomposes Answer: A) It readily reacts and dissolves
- What is the boiling point of polonium?
- A) 254°C
- B) 962°C
- C) 138.9 days
- D) It does not boil Answer: B) 962°C
- What is the symbol for polonium?
- A) P
- B) Pl
- C) Po
- D) Pol Answer: C) Po
- In what form does polonium exist at room temperature?
- A) Liquid
- B) Gas
- C) Solid
- D) Plasma Answer: C) Solid
- What is the density of polonium?
- A) 84 g/cm^3
- B) 125 g/cm^3
- C) 9.32 g/cm^3
- D) 16 g/cm^3 Answer: C) 9.32 g/cm^3
- Which element did Mendeleev predict would precede polonium?
- A) Uranium
- B) Bismuth
- C) Lead
- D) Mercury Answer: B) Bismuth
- What is the primary reason polonium is kept in a sealed container?
- A) To prevent oxidation
- B) To contain its radioactivity
- C) To maintain its color
- D) To prevent evaporation Answer: B) To contain its radioactivity
- What type of particles does polonium-210 emit?
- A) Beta particles
- B) Gamma rays
- C) Alpha particles
- D) Neutrons Answer: C) Alpha particles
- Which of the following is NOT a use of polonium?
- A) Source of alpha particles
- B) Source of atomic heat
- C) Source of gamma rays
- D) Lightweight thermoelectric power source Answer: C) Source of gamma rays
- How is polonium-210 utilized in antistatic devices?
- A) By emitting gamma rays
- B) By emitting alpha particles
- C) By absorbing static charges
- D) By generating electric fields Answer: B) By emitting alpha particles
- What is the origin of polonium’s name?
- A) Named after a scientist
- B) Named after its color
- C) Named after its country of discovery
- D) Named after its primary use Answer: C) Named after its country of discovery
Summary
In this tutorial, we explored the fascinating element of polonium, covering its occurrence, properties, uses, and isotopes. Polonium, with an atomic number of 84 and atomic mass of 209, is a metalloid found in group 16 of the periodic table. Its discovery by Marie Curie and Pierre Curie in 1898 led to its naming after their native country, Poland. Polonium is primarily obtained by bombarding bismuth-209 in nuclear reactors, yielding the highly radioactive polonium-210, which is known for its strong alpha emission.
Properties of polonium include its radioactivity, low melting point, and volatility, with notable uses in nuclear reactors, antistatic devices, and as a thermoelectric power source. Despite its lack of significant biological role, polonium-210’s presence in cigarette smoke highlights its toxicity and carcinogenic properties. Additionally, we discussed the isotopes of polonium, noting its lack of stable isotopes and the importance of polonium-209, discovered by Marie Curie, due to its relatively long half-life.
This tutorial provides a comprehensive understanding of polonium, its characteristics, and its diverse applications in various fields.