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Metals, alloys and elements

Thallium

Also known as Ramor, Thallium, elemental, Thulium Metallicum

CAS 7440-28-0Formula TlMolar mass 204.38 g/molEC 231-138-1
GHS signal word: Danger. Pictograms: Acute toxicity (severe), Serious health hazard 36 suppliers listed Drug substance
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Element with atomic number and standard atomic weight

Key facts

What buyers check first

All properties
Appearance
Bluish-white, very soft, inelastic, easily fusible, heavy metal
Melting point
304 °C
Boiling point
1,473 °C
Density
11.8 g/cm³
Flash point
215.6 °C
HS code
811251
Category
Metals, alloys and elements
UN number
UN 3288
Illustrative photo, fine white powder in an amber glass reagent bottle on a laboratory bench
Typical packagingIllustrative packaging image, not the actual product

What is Thallium?

Plain description, key identifiers and synonyms

Thallium is a naturally occurring trace metalloid element with atomic symbol Tl, atomic number 81, and atomic weight 204.383. Thallium is used in manufacturing, as well as in some chemical reactions and medical procedures. Use as a pesticide has been banned in the United States due to toxicity from accidental exposure. It is characterized as an odorless, bluish-white, metallic soft solid that turns to a gray powder with an aromatic odor when exposed to air. Exposure occurs by inhalation of fumes, ingestion, or contact.

Thallium is a chemical element with symbol Tl and atomic number 81.

Identifiers

Registry numbers, names and line notations, tap to copy

IUPAC name
thallium
CAS number
7440-28-0 CAS number cross-checked
EC number
231-138-1
Molecular formula
Tl
UNII
AD84R52XLF
InChIKey
BKVIYDNLLOSFOA-UHFFFAOYSA-N
InChI
InChI=1S/Tl
SMILES (canonical and isomeric)
[Tl]

Synonyms

  • Ramor
  • Thallium, elemental
  • Thulium Metallicum
  • lambda1-thallanylium
  • Thallium 205
  • Muscle spasms
  • Thallium metallicum
  • 81Tl
  • Talio
  • Tl
  • Thallium granules
  • Ramor, Thallium, metallic, Thallium, elemental,
  • Thallium Standard: Tl @ 1000 microg/mL in 5% HNO3
  • Thallium Standard: Tl @ 10000 microg/mL in 5% HNO3
  • Thallium AA Standard: Tl @ 1000 microg/mL in 5% HNO3
  • Thallium Standard: Tl @ 1000 microg/g in Hydrocarbon Oil
  • thallium atom
  • Atomic Thallium
  • Element Thallium
  • Element-Tl
  • Element:Thallium
  • Element:Tl
  • thallium metallic
  • Sulfur-Free Thallium Concentrate: Tl @ approx. 3 wt% in Hydrocarbons
  • thallium elemental
Show all 37 synonyms
  • Thallium (atomic)
  • Tl (element)
  • Thallium (element)
  • Thallium element
  • Thallium Nanoparticle Dispersion
  • Thallium, 99.98%
  • Thallium rod, 12.7mm (0.5in) dia
  • Thallium granules, 6mm (0.2in) & down
  • AA standard THALLIUM 1M HNO3 10000 ppm
  • Thallium - Tl @ 1000 microg/mL in 5% HNO3
  • Thallium - Tl @ 1000 microg/g in Hydrocarbon Oil
  • Thallium Hollow Cathode Lamp: 2.0" Diameter, 4-pin, Cableless

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
Bluish-white, very soft, inelastic, easily fusible, heavy metalexp.
Melting point
304 °Cexp.
Boiling point
1,473 °Cexp.
Density
11.8 g/cm³exp.
Flash point
215.6 °Cexp.
Solubility
Insoluble in water, reacts with acidexp.
Vapour pressure
1.59 × 10⁻⁵ Pa at 400 K, 0.0931 at 800 K, 16.9 Pa at 1000 K /Calculated/exp.

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
204.38 g/molcalc.
Exact mass
204.9744 Dacalc.
LogP (octanol/water)
-0.38calc.
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
GHS06: Acute toxicity (severe)
Acute toxicity (severe)
GHS08: Serious health hazard
Serious health hazard

Hazard statements

  • H300Fatal if swallowed.
  • H330Fatal if inhaled.
  • H373May cause damage to organs through prolonged or repeated exposure.
  • H413May cause long lasting harmful effects to aquatic life.
Precautionary statements (16)
  • P260Do not breathe dust, fume, gas, mist, vapours or spray.
  • P264Wash skin thoroughly after handling.
  • P270Do not eat, drink or smoke when using this product.
  • P271Use only outdoors or in a well-ventilated area.
  • P273Avoid release to the environment.
  • P284In case of inadequate ventilation wear respiratory protection.
  • P301 + P316If swallowed: Get emergency medical help immediately.
  • P304 + P340If inhaled: Remove person to fresh air and keep comfortable for breathing.
  • P316Get emergency medical help immediately.
  • P319Get medical help if you feel unwell.
  • P320Specific treatment is urgent (see supplemental first aid instructions on the label).
  • P321Specific treatment (see supplemental first aid instructions on the label).
  • P330Rinse mouth.
  • 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 3288
Transport hazard class
6.1
Packing group
II

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

Thallium suppliers

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All 36 suppliers
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Where suppliers are based

36 suppliers in 11 countries

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Thallium 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

Thallium-203 is a target for accelerator production of thalium-201, which is used in cardiac imaging.

The unalloyed metal is unsuitable for direct use, owing to its unfavorable mechanical properties and marked tendency to oxidize.

In semi-conductor industry, alloyed with mercury for switches and closures which operate at subzero temperatures.

In photoelectric cells, lamps, and, in electronics, in scintillation counters. As catalyst in organic synthesis.

Thallium was discovered by Sir William Crookes in 1861. It is a soft, heavy, inelastic metal. Thallium is tasteless and odorless and has been used by murderers as a difficult to detect poison. It is found in trace amounts in the earth’s crust. Thallium has not been produced in the United States since 1984, but is imported for use in the manufacture of electronics, low temperature thermometers, optical lenses, and imitation precious jewels.

Read more

It also has use in some chemical reactions and medical procedures. Thallium was used historically as a rodenticide, but has since been banned in the United States due to its toxicity from accidental exposure.

Use classes: Inorganic substances.

Functional uses

  • Surface modifier

How it is made

Flue dusts from lead and zinc smelting. The thallium compounds recovered are treated to obtain the metal by electrolysis, precipitation, or reduction.

The simplest process is leaching with water without pretreatment. With airborne dusts from lead or zinc smelting works, or cementation slimes, a yield of 85-90% of the thallium can be obtained. The thallium-containing liquor, which usually also contains cadmium and zinc, is filtered, precipitated with zinc amalgam, and the relatively pure metal is obtained by an electrolytic process.

Methods ...

Read more

(for) pretreating the starting material before leaching ... include: oxidative roasting at 500 °C, sulfatization at 175-250 °C, and alkaline pretreatment. Leaching of the raw material after pretreatment can extract 50-60% of the thallium. Flue dusts that contain bismuth, copper, zinc, iron, arsenic, cadmium, thallium, selenium, etc., are given an alkaline pretreatment (fusion with caustic soda and lead sulfide). The alkaline slag so formed is granulated with hot water. On cooling, sodium and thallium arsenates are precipitated, and processed to obtain the thallium.

Regulatory status

Inventories, regulations and trade controls that list this substance

Europe

  • EU harmonised classification (CLP Annex VI)
    Index no: 081-001-00-3

Health and food

  • EU Cosmetics Regulation Annex II, prohibited in cosmetics
    Name: Thallium and its compounds, Ref no: 317, Annex ref: II/317
  • Active ingredient in FDA approved drug labels

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 Thallium is traded under.

HS 8112.51Indicative HS code

Unwrought thallium, powders

Our trade statistics cover HS chapters 25 to 40 (minerals, chemicals, plastics and rubber). This code is in chapter 81, metals, which is not included yet.

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

The HS code shown for Thallium is indicative (it is known at chapter level only). Confirm the classification with your customs broker before shipping.

Frequently asked questions

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

What is Thallium?

Thallium is a naturally occurring trace metalloid element with atomic symbol Tl, atomic number 81, and atomic weight 204.383. Thallium is used in manufacturing, as well as in some chemical reactions and medical procedures. Use as a pesticide has been banned in the United States due to toxicity from accidental exposure.

What is the CAS number of Thallium?

The CAS registry number of Thallium is 7440-28-0.

What is the molecular formula and weight of Thallium?

The molecular formula of Thallium is Tl and its molar mass is 204.38 g/mol.

What is Thallium used for?

Thallium-203 is a target for accelerator production of thalium-201, which is used in cardiac imaging. The unalloyed metal is unsuitable for direct use, owing to its unfavorable mechanical properties and marked tendency to oxidize.

Is Thallium hazardous?

Thallium carries the GHS signal word "Danger". Main hazards: fatal if swallowed, fatal if inhaled, may cause damage to organs through prolonged or repeated exposure. This summary is not an SDS, always read the supplier safety data sheet.

What is the HS code of Thallium?

Thallium is usually classified under HS code 811251 (Unwrought, powders). This is indicative, confirm it with your customs broker before shipping.

Where can I buy Thallium?

CompoundList lists 36 suppliers of Thallium in United States, China, Germany, Spain and 7 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 Thallium?

Suppliers quote Thallium 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 Thallium

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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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