90
Th
Thorium

Thorium

Element 90 • Actinide
Atomic Mass 232.037700
Electron Config Unknown
Group/Period ?/7

Physical Properties

MEASURED
Atomic Mass
232.037700 u
Melting Point
1841.00 °C
Boiling Point
3500.00 °C
Ionization Energy
5.59 kJ/mol

Special Properties

CLASSIFIED
RADIOACTIVE This element emits radiation

Applications

CATALOGUED

Nuclear Fuel Applications

Thorium is increasingly recognized as a next-generation nuclear fuel with significant advantages over uranium-based fuels. Thorium-232, when bombarded with neutrons, converts to uranium-233, which is an excellent fissile material for nuclear reactors. This Thorium fuel cycle produces less long-lived radioactive waste and cannot easily be weaponized, making it an attractive option for peaceful nuclear energy.

Molten Salt Reactors

Thorium is the preferred fuel for molten salt reactor (MSR) technology, where Thorium fluoride is dissolved in molten salt that serves as both fuel and coolant. These reactors can operate at atmospheric pressure, have inherent safety features, and can consume existing nuclear waste. Countries like China and India are investing heavily in Thorium MSR development.

Gas Mantles and High-Temperature Applications

Historically, Thorium's most common use was in gas lantern mantles, where Thorium dioxide provided intense, bright light when heated. Although largely phased out due to radioactivity concerns, Thorium compounds are still used in specialized high-temperature applications, including refractory materials for crucibles and furnace linings that must withstand extreme heat.

Specialty Alloys and Materials

Thorium is used to create specialized magnesium-Thorium alloys for aerospace applications, where high strength-to-weight ratios are critical. These alloys maintain their properties at elevated temperatures, making them valuable for jet engine components and missile applications. The addition of small amounts of Thorium significantly improves the creep resistance of magnesium alloys.

Scientific and Research Applications

Research institutions use Thorium in various applications, including neutron sources, radiation detection equipment calibration, and fundamental nuclear physics research. Thorium compounds serve as reference standards for radiation measurements and are used in studying heavy element chemistry and nuclear decay processes.

Future Energy Applications

Advanced nuclear technologies are exploring Thorium's potential in accelerator-driven systems (ADS) and small modular reactors (SMRs). These systems could provide clean, safe nuclear power with reduced waste production and enhanced proliferation resistance, making Thorium a key element in future sustainable energy strategies.

Common Uses

INDEXED

Nuclear Energy Research

Thorium's most promising modern application is in advanced nuclear reactor designs. Research programs worldwide are developing Thorium molten salt reactors, which could provide safer, cleaner nuclear energy. India's three-stage nuclear program specifically targets Thorium utilization, given the country's large Thorium reserves.

High-Temperature Materials

Thorium dioxide (thoria) is used in specialized refractory applications where extreme temperature resistance is required. Its melting point of 3,300°C makes it valuable for crucibles, furnace linings, and high-temperature laboratory equipment used in materials research and metal processing.

Aerospace Alloys

Small amounts of Thorium are added to magnesium alloys to create materials with excellent high-temperature properties for aerospace applications. These alloys maintain strength and resistance to creep at elevated temperatures, making them suitable for aircraft engines and structural components.

Scientific Instrumentation

Thorium compounds serve as calibration standards for radiation detection equipment and as sources for neutron activation analysis. Research facilities use Thorium isotopes for studying nuclear decay processes and developing new radiochemical techniques.

Emerging Technologies

Thorium is being investigated for use in small modular reactors and other advanced nuclear technologies that could provide decentralized, clean energy. Its abundance and favorable nuclear properties make it an attractive alternative to uranium for future energy systems.

Natural Occurrence

SURVEYED

Abundant Natural Deposits

Thorium is relatively abundant in the Earth's crust, with an average concentration of 9.6 parts per million, making it about three times more abundant than uranium. It occurs primarily in igneous rocks and is concentrated in heavy mineral sands formed by weathering and erosion processes.

Primary Thorium Minerals

The most important Thorium-bearing mineral is monazite (a rare earth phosphate containing 4-12% Thorium dioxide), found in beach sands and river deposits. Other significant minerals include thorite (Thorium silicate), thorianite (Thorium dioxide), and bastnasite, which contains both Thorium and rare earth elements.

Global Distribution

Major Thorium deposits are located in India, Australia, Brazil, and the United States. India possesses the world's largest Thorium reserves, primarily in monazite beach sands along its eastern and southwestern coasts. Australia's reserves are mainly in mineral sands, while Brazil's deposits are in monazite-rich beach sands and weathered rock formations.

Mining and Extraction

Thorium is typically obtained as a byproduct of rare earth element mining rather than being mined specifically for Thorium. The extraction process involves acid leaching of monazite concentrates, followed by chemical separation techniques to isolate Thorium from rare earth elements and other components.

Environmental Occurrence

Thorium occurs naturally in granite rocks, soil, and water at low concentrations. It's present in coal at levels of 1-20 parts per million, and burning coal releases Thorium into the atmosphere. Natural background radiation includes a small contribution from Thorium and its decay products.

Discovery

ARCHIVED
1828

Jöns Jacob Berzelius Discovery

Thorium was discovered in 1828 by Swedish chemist Jöns Jacob Berzelius, one of the founding fathers of modern chemistry. Berzelius identified the new element while analyzing a black mineral sample sent to him by Norwegian mineralogist Morten Thrane Esmark, who had found it near Løvøya island in Norway.

The Norwegian Connection

The original sample was discovered by Morten Thrane Esmark in 1828 on the island of Løvøya in the Langesundsfjord region of Norway. Esmark, unable to identify the unusual black mineral, sent it to Berzelius in Stockholm for analysis. This collaboration between Norwegian field work and Swedish analytical chemistry led to the element's discovery.

Chemical Analysis

Berzelius used his advanced analytical techniques to isolate and characterize the new element. He initially thought he had discovered two new elements, which he named "thorium" and "thorina." Later analysis revealed these were the same element in different oxidation states. The name "thorium" was chosen after Thor, the Norse god of thunder.

19th Century Chemistry

The discovery occurred during the golden age of element discovery, when chemists were systematically analyzing new minerals using improved analytical methods. Berzelius's work with thorium contributed to the development of atomic weight determination and helped establish principles of chemical analysis that remain important today.

Radioactivity Discovery

Thorium's radioactive properties weren't discovered until 1898 by Gerhard Carl Schmidt and Marie Curie independently. This discovery came shortly after Becquerel's discovery of radioactivity and established thorium as only the second known radioactive element after uranium, launching the field of nuclear chemistry.

Scientific Legacy

The discovery of thorium exemplified 19th-century collaborative chemistry and established the foundation for understanding actinide elements. Berzelius's methodical approach to isolating and characterizing thorium became a model for discovering and studying other heavy elements.

Safety Information

CRITICAL

Radioactive Material

WARNING: Thorium is naturally radioactive with a half-life of 14 billion years.
While less intensely radioactive than many artificial isotopes, it still poses health risks through alpha radiation and the production of radioactive decay products, including radon gas.

Inhalation Risks

The primary health concern is inhalation of Thorium dust or particles, which can lodge in lung tissue and cause long-term radiation exposure. Workers in Thorium processing facilities or research laboratories must use appropriate respiratory protection and work in well-ventilated areas.

Handling Procedures

Thorium compounds should be handled using standard radiological safety protocols, including personal protective equipment, radiation monitoring, and proper storage in shielded containers. Areas where Thorium is used must be regularly monitored for radiation levels and contamination.

Historical Exposure Concerns

Past use of Thorium in gas mantles and consumer products created potential exposure pathways. Old gas mantles should be handled carefully and disposed of as radioactive waste. Some vintage ceramics and welding rods may contain Thorium and require proper handling.

Knowledge Database

Essential information about Thorium (Th)

Thorium is unique due to its atomic number of 90 and belongs to the Actinide category. With an atomic mass of 232.037700, it exhibits distinctive properties that make it valuable for various applications.

Thorium has several important physical properties:

Melting Point: 1841.00 K (1568°C)

Boiling Point: 3500.00 K (3227°C)

State at Room Temperature: solid

Atomic Radius: 180 pm

Thorium has various important applications in modern technology and industry:

Nuclear Fuel Applications

Thorium is increasingly recognized as a next-generation nuclear fuel with significant advantages over uranium-based fuels. Thorium-232, when bombarded with neutrons, converts to uranium-233, which is an excellent fissile material for nuclear reactors. This Thorium fuel cycle produces less long-lived radioactive waste and cannot easily be weaponized, making it an attractive option for peaceful nuclear energy.

Molten Salt Reactors

Thorium is the preferred fuel for molten salt reactor (MSR) technology, where Thorium fluoride is dissolved in molten salt that serves as both fuel and coolant. These reactors can operate at atmospheric pressure, have inherent safety features, and can consume existing nuclear waste. Countries like China and India are investing heavily in Thorium MSR development.

Gas Mantles and High-Temperature Applications

Historically, Thorium's most common use was in gas lantern mantles, where Thorium dioxide provided intense, bright light when heated. Although largely phased out due to radioactivity concerns, Thorium compounds are still used in specialized high-temperature applications, including refractory materials for crucibles and furnace linings that must withstand extreme heat.

Specialty Alloys and Materials

Thorium is used to create specialized magnesium-Thorium alloys for aerospace applications, where high strength-to-weight ratios are critical. These alloys maintain their properties at elevated temperatures, making them valuable for jet engine components and missile applications. The addition of small amounts of Thorium significantly improves the creep resistance of magnesium alloys.

Scientific and Research Applications

Research institutions use Thorium in various applications, including neutron sources, radiation detection equipment calibration, and fundamental nuclear physics research. Thorium compounds serve as reference standards for radiation measurements and are used in studying heavy element chemistry and nuclear decay processes.

Future Energy Applications

Advanced nuclear technologies are exploring Thorium's potential in accelerator-driven systems (ADS) and small modular reactors (SMRs). These systems could provide clean, safe nuclear power with reduced waste production and enhanced proliferation resistance, making Thorium a key element in future sustainable energy strategies.

1828

Jöns Jacob Berzelius Discovery

Thorium was discovered in 1828 by Swedish chemist Jöns Jacob Berzelius, one of the founding fathers of modern chemistry. Berzelius identified the new element while analyzing a black mineral sample sent to him by Norwegian mineralogist Morten Thrane Esmark, who had found it near Løvøya island in Norway.

The Norwegian Connection

The original sample was discovered by Morten Thrane Esmark in 1828 on the island of Løvøya in the Langesundsfjord region of Norway. Esmark, unable to identify the unusual black mineral, sent it to Berzelius in Stockholm for analysis. This collaboration between Norwegian field work and Swedish analytical chemistry led to the element's discovery.

Chemical Analysis

Berzelius used his advanced analytical techniques to isolate and characterize the new element. He initially thought he had discovered two new elements, which he named "thorium" and "thorina." Later analysis revealed these were the same element in different oxidation states. The name "thorium" was chosen after Thor, the Norse god of thunder.

19th Century Chemistry

The discovery occurred during the golden age of element discovery, when chemists were systematically analyzing new minerals using improved analytical methods. Berzelius's work with thorium contributed to the development of atomic weight determination and helped establish principles of chemical analysis that remain important today.

Radioactivity Discovery

Thorium's radioactive properties weren't discovered until 1898 by Gerhard Carl Schmidt and Marie Curie independently. This discovery came shortly after Becquerel's discovery of radioactivity and established thorium as only the second known radioactive element after uranium, launching the field of nuclear chemistry.

Scientific Legacy

The discovery of thorium exemplified 19th-century collaborative chemistry and established the foundation for understanding actinide elements. Berzelius's methodical approach to isolating and characterizing thorium became a model for discovering and studying other heavy elements.

Discovered by: <div class="discovery-section"> <h3><i class="fas fa-user-graduate"></i> Jöns Jacob Berzelius Discovery</h3> <p>Thorium was discovered in <strong>1828 by Swedish chemist Jöns Jacob Berzelius</strong>, one of the founding fathers of modern chemistry. Berzelius identified the new element while analyzing a black mineral sample sent to him by Norwegian mineralogist Morten Thrane Esmark, who had found it near Løvøya island in Norway.</p> <h3><i class="fas fa-hammer"></i> The Norwegian Connection</h3> <p>The original sample was discovered by <strong>Morten Thrane Esmark</strong> in 1828 on the island of Løvøya in the Langesundsfjord region of Norway. Esmark, unable to identify the unusual black mineral, sent it to Berzelius in Stockholm for analysis. This collaboration between Norwegian field work and Swedish analytical chemistry led to the element's discovery.</p> <h3><i class="fas fa="laboratory"></i> Chemical Analysis</h3> <p>Berzelius used his advanced analytical techniques to isolate and characterize the new element. He initially thought he had discovered two new elements, which he named "thorium" and "thorina." Later analysis revealed these were the same element in different oxidation states. The name "thorium" was chosen after <strong>Thor, the Norse god of thunder</strong>.</p> <h3><i class="fas fa-microscope"></i> 19th Century Chemistry</h3> <p>The discovery occurred during the golden age of element discovery, when chemists were systematically analyzing new minerals using improved analytical methods. Berzelius's work with thorium contributed to the development of <strong>atomic weight determination</strong> and helped establish principles of chemical analysis that remain important today.</p> <h3><i class="fas fa-radiation"></i> Radioactivity Discovery</h3> <p>Thorium's radioactive properties weren't discovered until <strong>1898 by Gerhard Carl Schmidt and Marie Curie</strong> independently. This discovery came shortly after Becquerel's discovery of radioactivity and established thorium as only the second known radioactive element after uranium, launching the field of nuclear chemistry.</p> <h3><i class="fas fa-award"></i> Scientific Legacy</h3> <p>The discovery of thorium exemplified 19th-century collaborative chemistry and established the foundation for understanding actinide elements. Berzelius's methodical approach to isolating and characterizing thorium became a model for discovering and studying other heavy elements.</p> </div>

Year of Discovery: 1828

Abundant Natural Deposits

Thorium is relatively abundant in the Earth's crust, with an average concentration of 9.6 parts per million, making it about three times more abundant than uranium. It occurs primarily in igneous rocks and is concentrated in heavy mineral sands formed by weathering and erosion processes.

Primary Thorium Minerals

The most important Thorium-bearing mineral is monazite (a rare earth phosphate containing 4-12% Thorium dioxide), found in beach sands and river deposits. Other significant minerals include thorite (Thorium silicate), thorianite (Thorium dioxide), and bastnasite, which contains both Thorium and rare earth elements.

Global Distribution

Major Thorium deposits are located in India, Australia, Brazil, and the United States. India possesses the world's largest Thorium reserves, primarily in monazite beach sands along its eastern and southwestern coasts. Australia's reserves are mainly in mineral sands, while Brazil's deposits are in monazite-rich beach sands and weathered rock formations.

Mining and Extraction

Thorium is typically obtained as a byproduct of rare earth element mining rather than being mined specifically for Thorium. The extraction process involves acid leaching of monazite concentrates, followed by chemical separation techniques to isolate Thorium from rare earth elements and other components.

Environmental Occurrence

Thorium occurs naturally in granite rocks, soil, and water at low concentrations. It's present in coal at levels of 1-20 parts per million, and burning coal releases Thorium into the atmosphere. Natural background radiation includes a small contribution from Thorium and its decay products.

⚠️ Caution: Thorium is radioactive and requires special handling procedures. Only trained professionals should work with this element.

Radioactive Material

WARNING: Thorium is naturally radioactive with a half-life of 14 billion years.
While less intensely radioactive than many artificial isotopes, it still poses health risks through alpha radiation and the production of radioactive decay products, including radon gas.

Inhalation Risks

The primary health concern is inhalation of Thorium dust or particles, which can lodge in lung tissue and cause long-term radiation exposure. Workers in Thorium processing facilities or research laboratories must use appropriate respiratory protection and work in well-ventilated areas.

Handling Procedures

Thorium compounds should be handled using standard radiological safety protocols, including personal protective equipment, radiation monitoring, and proper storage in shielded containers. Areas where Thorium is used must be regularly monitored for radiation levels and contamination.

Historical Exposure Concerns

Past use of Thorium in gas mantles and consumer products created potential exposure pathways. Old gas mantles should be handled carefully and disposed of as radioactive waste. Some vintage ceramics and welding rods may contain Thorium and require proper handling.

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