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Metals, alloys and elements

Thorium

Also known as 232Th, 90Th, Th

CAS 7440-29-1Formula ThMolar mass 232.04 g/molEC 231-139-7
GHS signal word: Danger. Pictograms: Oxidiser, Harmful or irritant, Serious health hazard 15 suppliers listed
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Element with atomic number and standard atomic weight

Key facts

What buyers check first

All properties
Appearance
Soft gray-white metal, cubic
Melting point
1,750 °C
Boiling point
4,788 °C
Density
11.7 g/cm³
Solubility
Insoluble in water, soluble in hydrochloric acid, sulfuric acid, aqua regia, slightly so…
HS code
284430
Category
Metals, alloys and elements
UN number
UN 2912
Illustrative photo, grey powder in an open woven sack in a warehouse
Typical packagingIllustrative packaging image, not the actual product

What is Thorium?

Plain description, key identifiers and synonyms

Thorium is an actinoid atom and a f-block element atom.

Thorium is a chemical element with symbol Th and atomic number 90.

Identifiers

Registry numbers, names and line notations, tap to copy

IUPAC name
thorium
CAS number
7440-29-1 CAS number cross-checkedOther or deprecated CAS: 15117-56-3
EC number
231-139-7
Molecular formula
Th
UNII
60YU5MIG9W
InChIKey
ZSLUVFAKFWKJRC-UHFFFAOYSA-N
InChI
InChI=1S/Th
SMILES (canonical and isomeric)
[Th]

Synonyms

  • 232Th
  • 90Th
  • Th
  • torio
  • Thorium, elemental
  • Thorium metal, pyrophoric
  • Thorium metal, pyrophoric [UN2975] [Radioactive]
  • Thorium Standard: Th @ 1000 microg/mL in 5% HNO3
  • Thorium Standard: Th @ 10000 microg/mL in 5% HNO3
  • Thorium element
  • Atomic Thorium
  • Element Thorium
  • Element:Thorium
  • Thorium atom
  • Element-Th
  • Element:Th
  • Thorium (atomic)
  • Th (element)
  • Thorium (element)
  • Th Standard Solution
  • Thorium, 99.1%, powder
  • AA standard THORIUM 1M HNO3 1000 ppm
  • AA standard THORIUM 1M HNO3 10000 ppm
  • Thorium - Th @ 1000 microg/mL in 5% HNO3
  • ICP standard Thorium 2-5% HNO3 1000 microg/mL

Physical and chemical properties

Measured values and descriptors computed from the structure

Physical and chemical properties

Measured values, check the supplier specification for your grade

Appearance
Soft gray-white metal, cubicexp.
Melting point
1,750 °Cexp.
Boiling point
4,788 °Cexp.
Density
11.7 g/cm³exp.
Autoignition temperature
270 °Cexp.
Solubility
Insoluble in water, soluble in hydrochloric acid, sulfuric acid, aqua regia, slightly soluble in nitric acidexp.
Vapour pressure
Log(p/atm) = -28,780 (T/K)-1 + 5991 at 1757-1956 Kexp.

Values vary by grade. Ask suppliers for the COA or TDS of the batch you buy.

Computed descriptors

Calculated from the structure, useful for screening and formulation

Molecular weight
232.04 g/molcalc.
Exact mass
232.0381 Dacalc.
LogP (octanol/water)
0calc.
Topological polar surface area
0 Ųcalc.
Hydrogen bond donors
0calc.
Hydrogen bond acceptors
0calc.
Rotatable bonds
0calc.
Heavy atoms
1calc.
Rings
0calc.
Aromatic rings
0calc.
Fraction sp3 carbons
0calc.
Formal charge
0calc.
Stereocentres
0calc.

Calculated for screening. Confirm critical figures with the supplier.

Safety and hazards

GHS classification summary, not a safety data sheet

GHS signal word
Danger
GHS03: Oxidiser
Oxidiser
GHS07: Harmful or irritant
Harmful or irritant
GHS08: Serious health hazard
Serious health hazard

Hazard statements

  • H272May intensify fire, oxidiser.
  • H302Harmful if swallowed.
  • H315Causes skin irritation.
  • H319Causes serious eye irritation.
  • H335May cause respiratory irritation.
  • H373May cause damage to organs through prolonged or repeated exposure.
Precautionary statements (23)
  • P210Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
  • P220Keep away from clothing and other combustible materials.
  • P260Do not breathe dust, fume, gas, mist, vapours or spray.
  • P261Avoid breathing dust, fume, gas, mist, vapours or spray.
  • P264Wash skin thoroughly after handling.
  • P264 + P265Wash skin thoroughly after handling. Do not touch eyes.
  • P270Do not eat, drink or smoke when using this product.
  • P271Use only outdoors or in a well-ventilated area.
  • P280Wear protective gloves, protective clothing, eye protection and face protection.
  • P301 + P317If swallowed: Get medical help.
  • P302 + P352If on skin: Wash with plenty of water.
  • P304 + P340If inhaled: Remove person to fresh air and keep comfortable for breathing.
  • P305 + P351 + P338If in eyes: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P319Get medical help if you feel unwell.
  • P321Specific treatment (see supplemental first aid instructions on the label).
  • P330Rinse mouth.
  • P332 + P317If skin irritation occurs: Get medical help.
  • P337 + P317If eye irritation persists: Get medical help.
  • P362 + P364Take off contaminated clothing. And wash it before reuse.
  • P370 + P378In case of fire: Use appropriate media to extinguish.
  • P403 + P233Store in a well-ventilated place. Keep container tightly closed.
  • P405Store locked up.
  • P501Dispose of contents and container in accordance with local regulations.
UN number
UN 2912
Transport hazard class
7

GHS classification summary, not a safety data sheet (SDS). Classifications can differ by supplier, grade and concentration. Always check the supplier's SDS.

Full safety data and first aid

Thorium suppliers

Sponsored listings first, then the documented ranking: membership, verification, replies, completeness, freshness and ratings

All 15 suppliers
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Where suppliers are based

15 suppliers in 9 countries

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Thorium price

Indicative price range per kg from live supplier offers

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Uses and applications

What the substance is used for, by industry and function

Because the thorium atom density is higher in thorium metal than in any thorium compound, metal is the preferred form of thorium where the highest nuclear reactivity or highest density is wanted.

As fuel in nuclear reactors, as source of fissionable uranium-233. In manufacture of incandescent gas-light mantles, welding electrodes, ceramics. As hardener in Mg alloys, for filament coatings in incandescent lamps and vacuum tubes, as chemical catalyst.

Nuclear fuel (thorium-232 is converted to uranium-233 on neutron bombardment after several decay steps), sun lamps, photoelectric cells, target in X-ray tubes, alloys.

In ceramics & in welding electrodes.

Use classes: Inorganic substances, Radionuclides.

How it is made

The route to thorium metal is ... reaction of the oxide or a halide with metals, electrolysis in molten salts, or thermal decomposition of a halide. The principal reactions that have led to production processes are: ... 1) Electrolysis of fused salts: KThF5 in NaCl, ThF4 in NaCl - KCl, ThCl4 in NaCl - KCl. 2) Reduction with reactive metals: ThO2 with Ca, ThCl4 with Mg, ThF4 with Ca. 3) Thermal dissociation of ThI4. ...

Read more

The following four production methods have been tested on a full scale: (1) reduction of fluorides and chlorides, (2) reduction of ThO2, (3) thermal decomposition of ThI4, and (4) fused salt electrolysis.

It can be obtained by reducing thorium oxide with calcium, by electrolysis of anhydrous thorium chloride in fused mixture of sodium and potassium chlorides, by calcium redn of thorium tetrachloride mixed with anhydrous zinc chloride, and by redn of thorium tetrachloride with alkali metal.

(1) Reduction of thorium dioxide with calcium, (2) fused salt electrolysis of the double fluoride ThF4.KF. The product of both processes is thorium powder, fabricated into the metal by powder metallurgy techniques. Hot surface decomposition of the iodide produces crystal bar thorium.

Regulatory status

Inventories, regulations and trade controls that list this substance

United States

  • TSCA inventory (USA)
    Status: Active in US commerce

HS code and trade data

Customs classification and reported world trade statistics

Global trade

World import and export statistics for the HS code Thorium is traded under.

HS 2844.30Exact HS code

Uranium depleted in U 235 and its compounds, thorium and its compounds, alloys…

World exports in 2024
$91M
+16.8% vs 2023, imports $48M
2019 to 2024
Top exporters
  1. South Africa73.2%
  2. United States13.4%
  3. Sweden6.9%
Top importers
  1. Belgium53.7%
  2. France * partner reported9.2%
  3. Canada8.8%

* Partner reported figures, a lower bound.

Reported customs values in USD, not prices.Full trade data

The HS code shown for Thorium is indicative (it was matched by name in the HS nomenclature). Confirm the classification with your customs broker before shipping.

Frequently asked questions

Quick answers about Thorium, based on the data on this page

What is Thorium?

Thorium is an actinoid atom and a f-block element atom.

What is the CAS number of Thorium?

The CAS registry number of Thorium is 7440-29-1. Other or deprecated CAS numbers: 15117-56-3.

What is the molecular formula and weight of Thorium?

The molecular formula of Thorium is Th and its molar mass is 232.04 g/mol.

What is Thorium used for?

Because the thorium atom density is higher in thorium metal than in any thorium compound, metal is the preferred form of thorium where the highest nuclear reactivity or highest density is wanted. As fuel in nuclear reactors, as source of fissionable uranium-233.

Is Thorium hazardous?

Thorium carries the GHS signal word "Danger". Main hazards: may intensify fire, oxidiser, harmful if swallowed, causes skin irritation. This summary is not an SDS, always read the supplier safety data sheet.

What is the HS code of Thorium?

Thorium is usually classified under HS code 284430 (Uranium depleted in U 235 and its compounds, thorium and its compounds, alloys…). This is indicative, confirm it with your customs broker before shipping.

Where can I buy Thorium?

CompoundList lists 15 suppliers of Thorium in China, United States, Australia, Germany and 5 more. Send one free request to get and compare quotes. Your contact details stay private until you accept a quote.

What is the price of Thorium?

Suppliers quote Thorium on request because prices depend on grade, purity, quantity and destination. A free request on CompoundList gets you several quotes to compare.

Guides for buyers

Practical guides that help when you source, ship or handle Thorium

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Data last updated 7 Oct 2026. Details may have changed, please confirm them with the supplier. Report an error on this page
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