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Thorium is a weakly radioactive metallic chemical element. The symbol of thorium is Th. It is placed in the seventh row and f block of the periodic table. The atomic number of Thorium is 90 and it was identified by a Swedish Scientist named Jons Jacob Berzelius in the year 1828. It is a soft and silvery-white metal that looks like lead. It slowly transforms into a grey colour on reaction with oxides. Thorium can be bent, cut, rolled, and welded very easily.
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Key Terms: Thorium, Radioactive Element, Atomic Number, Oxides, Metal, Modern Periodic Table, Electron Configuration, Nuclear Fuel
What is Thorium?
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Thorium is a chemical element placed in the seventh row and f block of the modern periodic table with the atomic number 90 and is represented with the symbol ‘Th’ in the periodic table.
It is a silvery-white metal in its pure form and remains stable in the air. It remains lustrous for several months and when it reacts with oxides, it slowly changes into a grey colour. This element is found in small amounts in most rocks and soils.
Thorium
Physical Properties of Thorium
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The properties of thorium are majorly dependent on the number of impurities present in the sample and one of the impurities is thorium dioxide.
- Thorium is an electropositive metal and is highly reactive.
- When heated in the air, it burns magnificently with white light.
- Thorium has 90 electrons and has 4 electrons in the valence shell.
- It is slowly attacked by water but it does not readily dissolve in acids.
Read More: Electropositivity
Chemical Properties of Thorium
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The chemical properties of Thorium are tabulated below:
| Group | 12 |
| Period | 7 |
| Block | f |
| Atomic Number | 90 |
| State At 20°C | Solid |
| Electron Configuration | [Rn] 6d27s2 |
| Melting Point | 1750°C, 3182°F, 2023 K |
| Boiling Point | 4785°C, 8645°F, 5058 K |
| Density (g cm−3) | 11.7 |
| Key Isotopes | 230Th, 232Th |
| Relative Atomic Mass | 232.038 |
Atomic Number and Symbol of Thorium
Applications of Thorium
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- Thorium is studied as the source of nuclear fuel. It is used in nuclear reactors to burn it without generating plutonium. Thorium is used to date the hominid acid.
- Thorium is used in the manufacture of refractory materials in the metallurgical industries.
- When thorium is added to glass it creates a high refractive index and low glass dispersion.
- It is very helpful in radiometric prosperity
- It is used in magnesium as an alloying element; it is used in electronic equipment to control the plutonium grain size.
- Thorium is used in gas mantles.
Health Effects of Thorium
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Thorium is available all over the earth and it also reacts with our body very badly it is very harmful because it is available in air, water, and some amount of food we eat in daily life.
- Thorium is there in research that inhaling thorium dust increases the risk of lungs and cancer. The reason behind cancer is that it is a dangerous element and is stored in the bone.
- Those who work in milling and mining thorium have difficulties breathing when there is lots of thorium.
- Thorium can cause lung, liver cancer, or breathing problems which can cause death.
- It can also cause pancreas disease.
Read More: Atomic Mass of Elements
Things to Remember
- Thorium is from the group of actinide family and it is a weakly metallic radioactive metallic chemical element.
- It was identified by Jons Jacob Berzelius in 1828.
- The atomic number of Thorium is 90 and is represented with the symbol ‘Th’ in the periodic table.
- It is a silvery-white metal in its pure form and is stable in air and remains lustrous for several months.
- It turns grey when it reacts with oxides.
- The main use of Thorium lies in nuclear fuel applications and it is used as an alloying element in magnesium, to coat tungsten wire in electrical equipment.
Sample Questions
Ques. Mention the occurrence or sources of Thorium. (3 Marks)
Ans. Thorium is a naturally occurring radioactive metal that is found in small amounts in most rocks and soils, and it is about three times more abundant than Uranium. Soil contains around 6 parts per million (ppm) of thorium on average. Since it is very insoluble, it is plentiful in sands but not in seawater.
Ques. List down the reaction of Thorium with air and water. (3 Marks)
Ans. Thorium is slowly attacked by water, however, it does not dissolve readily in acids, except hydrochloric acid.
Thorium turnings ignite and burn brilliantly with a white light when heated in the air.
Ques. Explain the presence of thorium in the environment. (3 Marks)
Ans. Thorium is present in trace quantities in almost all rock, soil, water, plants and animals. Where there is a higher concentration in rock or sands, it may be mined and refined, producing waste products such as mill tailings, which if not properly controlled, water and wind can introduce the tailings into the wider environment.
Ques. What are the health effects related to thorium? (3 Marks)
Ans. Thorium may remain in the lungs for long periods of time, depending on the chemical form, if inhaled as dust. If thorium is ingested, it leaves the body through faeces and urine within several days. However, if a small amount of thorium is left in the body, it will enter the bloodstream and be deposited in the bones where it may remain for many years.
Ques. Explain the use of Thorium as nuclear fuel. (3 Marks)
Ans. The properties of Thorium allow it to be used to fuel a nuclear chain reaction which can be used to run a power plant and produce electricity. However, Thorium will not split itself and release energy. When exposed to neutrons, thorium will undergo a series of nuclear reactions until it emerges as an isotope of uranium called U-233, which will then readily split and release energy the next time it absorbs a neutron. Thus, Thorium is called fertile, while U-233 is called fissile.
Ques. List down the important chemical properties of Thorium. (3 Marks)
Ans. The chemical properties of Thorium are
- Group - Actinides
- Period– 7
- Block– f
- Atomic Number– 90
- State at 20°C– Solid
- Melting Point- 1750°C, 3182°F,2023K
- Boiling Point- 4785°C, 8645°F, 5058K
Ques. Give some applications of Thorium. (3 Marks)
Ans. Some of the applications of Thorium are:
- Thorium is used in magnesium as an alloying element.
- Thorium is used to cast the tungsten wire and is used in the electronic equipment to control the plutonium grain size that finds application in the electric lamps.
- It is used in the metallurgical industries for the manufacture of refractory materials.
- Thorium is being used to study it as a source of nuclear fuel.
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