Structure
Not a diagram of dots on rings — a Monte-Carlo sample of the actual probability density |ψ|² for each occupied subshell. Drag to rotate. Blue and violet mark opposite signs of the wavefunction, which is what makes bonding possible.
Measured values
Every bar shows where bismuth sits among all 118 elements for that property.
Sources: IUPAC 2021 standard atomic weights · CRC Handbook of Chemistry and Physics · NIST. Values marked ~ are predicted rather than measured.
Size, to scale
Radius 149 pm — that is 0.149 nm, so about 3356 million of them side by side would span a millimetre.
Thermal range
Bismuth is liquid over a 1292 K window, from 545 K to 1837 K.
The story
The heaviest element that is very nearly stable, and the one that grows spectacular rainbow crystals.
Bismuth's discovery story is one of gradual recognition rather than a single eureka moment. Ancient civilizations encountered bismuth for thousands of years but consistently confused it with lead or tin due to its similar appearance and low melting point.
Archaeological evidence suggests that Inca and other South American civilizations worked with native bismuth as early as 1400 CE, using it for decorative objects and tools. However, they didn't recognize it as a distinct metal, calling it by names that translates to "white lead" or "soft tin."
Medieval European miners in Germany and Bohemia (now Czech Republic) frequently encountered bismuth in silver and lead mines but dismissed it as an inferior form of lead that was difficult to work. They called it "wismut" or "wissmuth," possibly meaning "white mass" in old German.
The first person to systematically study bismuth as a potentially distinct metal was Basil Valentine, a German alchemist, around 1450. In his alchemical writings, he described a metal that was "like lead but not lead," noting its unusual properties including its brittleness when compared to lead's malleability.
However, the definitive recognition of bismuth as a unique element came much later through the work of Claude François Geoffroy in 1753. This French chemist conducted careful experiments comparing bismuth with lead and tin, demonstrating conclusively that bismuth was a distinct metal with its own characteristic properties.
Geoffroy's key observations included:
The name "bismuth" has murky origins that reflect the confusion surrounding its identity. The German miners' term "wismut" eventually evolved into the Latin "bismuthum" used by early chemists and alchemists.
Alternative theories suggest the name derives from the Arabic "bi ismid" meaning "having the properties of antimony," reflecting early confusion between bismuth and antimony compounds. Both elements produce similar-appearing white oxides and were often found together in mineral deposits.
Carl Linnaeus, the famous botanist who also contributed to chemical nomenclature, helped standardize the name "bismuth" in his systematic classification of natural substances in the mid-18th century.
The late 18th century brought systematic chemical investigation of bismuth. Antoine Lavoisier included bismuth in his significant list of chemical elements in 1789, definitively establishing it as a fundamental substance that could not be broken down further.
Torbern Bergman, a Swedish chemist, made significant contributions to understanding bismuth chemistry in the 1770s. He discovered several bismuth compounds and noted the element's unusual behavior - sometimes acting like a metal, other times showing properties more similar to metalloids.
Martin Heinrich Klaproth, who discovered uranium and zirconium, also worked extensively with bismuth in the 1790s. His precise analytical work established bismuth's atomic weight and confirmed its status as a distinct element.
The 19th century saw growing practical interest in bismuth. German pharmacist Valentin Rose developed bismuth subnitrate in 1786 as a medicinal compound, marking the beginning of bismuth's pharmaceutical applications.
The discovery of bismuth's unusual expansion upon freezing was made by several researchers in the early 1800s, leading to its use in type metal for printing. This property, shared with only a few other substances like water, made bismuth valuable for creating sharp, detailed castings.
Percy Williams Bridgman, who won the Nobel Prize for high-pressure physics, conducted extensive studies of bismuth's properties under extreme conditions in the early 20th century, revealing its complex phase behavior and contributing to modern solid-state physics.
The 20th century brought significant understanding of bismuth's properties. The discovery of its thermoelectric properties in the 1920s led to applications in temperature measurement and solid-state cooling devices.
Perhaps most surprisingly, in 2003, scientists at the Institut Laue-Langevin in France discovered that bismuth is actually weakly radioactive with an incredibly long half-life of 1.9 × 10¹⁹ years - longer than the age of the universe by a billion times. This makes bismuth the heaviest stable element for all practical purposes, though technically it's the longest-lived radioactive element.
Recent research has revealed bismuth's potential in quantum physics applications, particularly as a topological insulator. These discoveries show that even "ancient" elements can surprise us with new properties and applications.
Bismuth's discovery story reflects the gradual evolution of chemistry from alchemy to modern science. What began as confusion with other metals eventually led to recognition as a unique element with extraordinary properties that continue to surprise scientists today.
From medieval miners' "false lead" to modern quantum materials, bismuth exemplifies how scientific understanding deepens over centuries of investigation.
Applications
Bismuth subsalicylate (Pepto-Bismol) is the most familiar bismuth compound, used worldwide for treating digestive disorders including diarrhea, nausea, and stomach upset. The pink liquid contains bismuth in a form that coats the stomach lining and has mild antibacterial properties.
Helicobacter pylori treatment uses bismuth compounds as part of quadruple therapy regimens to eradicate the bacteria that causes stomach ulcers. Bismuth potassium citrate and colloidal bismuth subcitrate are prescribed medications that work synergistically with antibiotics.
Wound care products incorporate bismuth-based compounds for their antiseptic properties. Medical dressings containing bismuth help prevent infection while promoting healing, particularly for burns and chronic wounds.
Dental applications use bismuth oxide in root canal sealers and temporary filling materials. Bismuth's radiopacity makes it valuable for dental X-rays, allowing dentists to verify proper placement of fillings and treatments.
Fire sprinkler systems rely on bismuth-based low-melting-point alloys for temperature-sensitive triggers. These alloys melt at precisely controlled temperatures (typically 57-79°C), releasing water when fires reach dangerous levels.
Fusible links in fire doors and ventilation systems use bismuth alloys that melt to automatically close fire barriers or redirect air flow during emergencies. The predictable melting point ensures reliable operation under fire conditions.
Fire detection devices incorporate bismuth alloys in heat-sensitive elements that trigger alarms when ambient temperature exceeds safe limits. These systems provide early warning in industrial facilities and high-risk areas.
Lead-free soldering increasingly uses bismuth-containing alloys as environmentally safer alternatives to traditional lead-tin solders. Bismuth-tin and bismuth-silver-copper alloys provide excellent electrical conductivity and mechanical strength for electronics manufacturing.
Machineable alloys incorporate bismuth to improve the cutting properties of steel and other metals. Bismuth forms brittle inclusions that break away during machining, resulting in better surface finish and longer tool life.
Casting alloys use bismuth's unusual property of expanding upon solidification. This expansion helps fill mold cavities completely, producing castings with sharp detail and minimal shrinkage defects in decorative and precision applications.
Thermostat metals in bimetallic strips utilize bismuth alloys for temperature-responsive switching in heating and cooling systems. The differential expansion creates mechanical movement for temperature control.
Pearl essence and bismuth oxychloride create the shimmering, iridescent effects in makeup products including eyeshadows, lipsticks, and nail polishes. Bismuth's crystal structure produces unique optical properties that scatter light beautifully.
Foundation and concealer formulations use bismuth oxychloride for its light-reflecting properties that help minimize skin imperfections. The compound provides coverage while maintaining a natural appearance.
Specialized pigments containing bismuth produce unique colors and effects in automotive paints, artist materials, and decorative coatings. These pigments are valued for their stability and low-toxicity nature compared to heavy metal alternatives.
Neutron detection utilizes bismuth's nuclear properties in specialized radiation detectors for research reactors and particle accelerators. Bismuth-loaded plastic scintillators can discriminate between neutrons and gamma rays.
Thermoelectric devices employ bismuth telluride (Bi₂Te₃) as one of the most efficient thermoelectric materials available. These devices convert heat directly to electricity or provide solid-state cooling without moving parts.
Superconductor research investigates bismuth-based cuprate compounds that exhibit high-temperature superconductivity. BSCCO (bismuth strontium calcium copper oxide) family materials are important for understanding superconducting mechanisms.
Topological insulators based on bismuth compounds represent cutting-edge research in quantum materials. These materials conduct electricity on their surface while remaining insulating in their bulk, with potential applications in quantum computing.
Catalyst applications use bismuth compounds in organic synthesis, particularly for oxidation reactions and polymerization processes. Bismuth catalysts are often more environmentally friendly than traditional heavy metal catalysts.
Glass manufacturing incorporates bismuth oxide to create high-refractive-index optical glasses with unique properties for specialized lenses and prisms. These glasses are used in high-end optical instruments.
Nuclear applications utilize bismuth as a target material for producing polonium-210 and other radioisotopes. Bismuth's nuclear properties make it suitable for certain research and industrial radioisotope production.
Pepto-Bismol and similar products are the most common way people encounter bismuth. The familiar pink liquid contains bismuth subsalicylate, which helps with:
Unlike many stomach medications, bismuth-based products can safely be used by most people without prescription, though they can temporarily darken the tongue and stool.
Makeup products use bismuth oxychloride to create shimmering, pearl-like effects. You'll find bismuth in:
Bismuth-based cosmetics are considered safer alternatives to products containing lead or mercury-based ingredients.
Fire sprinkler systems in homes and buildings use bismuth alloys in their trigger mechanisms. These systems automatically activate when the temperature reaches about 155°F (68°C), with the bismuth alloy melting to release the sprinkler head.
Thermal fuses in household appliances often contain bismuth alloys that melt to break electrical circuits if overheating occurs, preventing fires in coffee makers, hair dryers, and space heaters.
Lead-free fishing weights increasingly use bismuth alloys as environmentally safer alternatives. These weights provide similar density to lead while being low-toxicity to wildlife and fish. Bismuth fishing weights are especially popular in areas where lead tackle is restricted.
Lead-free solder containing bismuth is increasingly used in electronics assembly as environmental regulations phase out lead-based solders. Bismuth-tin alloys provide:
Prescription medications for treating H. pylori infections (stomach ulcer bacteria) often include bismuth compounds. These work alongside antibiotics to eliminate the bacteria more effectively than antibiotics alone.
Dental procedures use bismuth-containing materials for temporary fillings and root canal treatments because bismuth shows up clearly on X-rays, helping dentists verify proper placement.
Metal casting by artists and hobbyists often uses bismuth alloys because they expand slightly when cooling, filling mold details perfectly. Bismuth creates beautiful crystalline structures when cooled slowly, making it popular for decorative casting.
Special effect paints containing bismuth compounds create unique color-shifting and iridescent effects in automotive painting, art projects, and decorative applications.
One of bismuth's greatest advantages is its relative safety compared to other heavy metals. Unlike lead, mercury, or cadmium, bismuth has very low toxicity and is even used medicinally. This makes it an excellent green alternative for many applications where toxic metals were previously used.
Key safety benefits include:
Bismuth has some fascinating properties that make it useful in unexpected ways:
Where it comes from
0.0085 mg/kg of Earth's crust · more abundant than 38% of elements
Bismuth is one of the rarest naturally occurring elements, with an average crustal abundance of only 0.009 parts per million (9 parts per billion). This makes it approximately 20,000 times rarer than lead and similar in abundance to precious metals like silver and gold.
Despite its rarity, bismuth is widely distributed in trace amounts throughout the Earth's crust. It shows a slight preference for granitic rocks over mafic rocks, reflecting its lithophile (rock-loving) behavior during magmatic differentiation processes.
The extreme rarity means that economic bismuth deposits are quite unusual and typically associated with other metallic ore deposits, particularly those containing lead, copper, tin, or tungsten.
Native bismuth metal is surprisingly common in nature compared to other metals, occurring as small silvery masses and crystals in hydrothermal veins. The largest native bismuth specimens come from Bolivia, Canada, and Germany, with some weighing several pounds.
Primary bismuth minerals include:
Many bismuth minerals form spectacular crystal specimens prized by collectors, particularly the geometric native bismuth crystals with their distinctive stepped, hopper-crystal shapes.
China dominates global bismuth production with approximately 80% of world supply, primarily from the Hunan, Guangxi, and Yunnan provinces. Most Chinese bismuth comes as a byproduct of lead-zinc mining and tungsten extraction.
Bolivia hosts some of the world's richest bismuth deposits in the Eastern Cordillera, particularly around Tasna and Chorolque. These high-altitude deposits (over 4,000m elevation) contain native bismuth associated with tin, tungsten, and silver mineralization.
Australia produces bismuth mainly from the Kingsgate mine in New South Wales and as a byproduct from Olympic Dam's copper-uranium operations. The country has significant reserves but limited active production.
Canada has historically important bismuth mines in the Yukon Territory (particularly around Mayo) and British Columbia, though most are inactive. Canada also recovers bismuth from copper smelting operations.
Peru and Mexico produce smaller amounts, mainly as byproducts of base metal mining operations, particularly from silver-lead deposits in their mountain ranges.
Hydrothermal deposits are the most important source of economic bismuth concentrations. These form when metal-rich fluids, typically at temperatures of 200-500°C, deposit bismuth minerals in veins, replacements, and contact metamorphic zones.
Pegmatite deposits sometimes contain bismuth minerals, formed during the final stages of granite crystallization when rare elements concentrate in residual fluids. These deposits often contain bismuth alongside other rare metals.
Contact metamorphic (skarn) deposits form where intrusive igneous rocks contact limestone or other carbonate rocks, creating high-temperature reaction zones where bismuth can precipitate with other chalcophile elements.
Greisen deposits associated with highly evolved granites can contain bismuth, particularly in tungsten-tin bearing systems where bismuth substitutes for other metals in sulfide minerals.
Most bismuth is actually recovered as a byproduct during the refining of other metals, particularly lead, copper, and tin. The bismuth concentrates in slimes, drosses, and other processing residues that are then treated to extract the bismuth.
Soils typically contain 0.01-0.3 ppm bismuth, with higher concentrations near mineralized areas or industrial activities. Bismuth doesn't readily leach from soils due to its low solubility in most natural waters.
Seawater contains extremely low bismuth concentrations (about 0.02 parts per billion), making it one of the least abundant elements in marine environments. The low concentration reflects bismuth's tendency to form insoluble compounds.
Freshwater systems generally contain even lower bismuth levels than seawater, typically less than 0.01 ppb. However, mining activities and industrial processing can locally elevate bismuth concentrations in water and sediments.
Atmospheric bismuth is extremely low under natural conditions but can be elevated near smelters and other industrial sources. Bismuth particles in air typically settle quickly due to the element's high density.
Global bismuth production is only about 8,000-12,000 tons annually, making it one of the least-produced metals commercially available. This small market size means that bismuth prices can be quite volatile and sensitive to supply disruptions.
World reserves are estimated at around 320,000 tons, with China holding the largest reserves followed by Australia and Bolivia. However, reserve estimates are uncertain due to bismuth's status as primarily a byproduct metal.
The strategic importance of bismuth is growing due to its use in green technologies and as a replacement for toxic metals, potentially increasing demand despite the limited supply base.
Handling
Bismuth is one of the safest heavy metals, with very low toxicity and extensive use in medicine and consumer products.
FDA approved for medicinal use: Bismuth compounds like bismuth subsalicylate (Pepto-Bismol) are widely used over-the-counter medications with an excellent safety record spanning over 100 years.
Low absorption: Bismuth compounds are poorly absorbed from the gastrointestinal tract, with less than 1% of ingested bismuth entering the bloodstream. Most passes through the body unchanged.
Therapeutic doses: Standard medicinal doses (525 mg bismuth subsalicylate every 30-60 minutes) are well-tolerated by most adults and children over 12 years old.
Elimination: Absorbed bismuth is rapidly excreted through urine and feces, with a biological half-life of only 3-5 days in most tissues.
Low-hazard discoloration: The most common "side effect" is temporary darkening of the tongue and stool, caused by bismuth sulfide formation. This is of low hazard and reversible.
Gastrointestinal effects: Large doses may cause constipation, nausea, or stomach upset. These effects are generally mild and resolve when dosing stops.
Allergic reactions: Rare allergic reactions to bismuth compounds can occur, typically manifesting as skin rash or digestive symptoms.
Salicylate sensitivity: People allergic to aspirin should avoid bismuth subsalicylate due to the salicylate component, not the bismuth itself.
Industrial handling: Bismuth metal and most compounds pose minimal health risks during normal industrial handling. Standard metal-working precautions are usually sufficient.
Dust inhalation: Prolonged inhalation of bismuth dust should be avoided. Use appropriate respiratory protection in dusty environments and ensure adequate ventilation.
Skin contact: Bismuth metal and most compounds are not skin sensitizers or irritants. Normal hygiene practices (washing hands after handling) are adequate.
Eye protection: As with any fine powder or metal dust, eye protection prevents mechanical irritation from bismuth particles.
Chemical reactivity: Bismuth metal is relatively unreactive under normal conditions. It oxidizes slowly in air and doesn't react with water at room temperature.
Acid reactions: Bismuth dissolves in concentrated nitric acid and hot sulfuric acid, producing nitrogen oxides or sulfur dioxide respectively. Use appropriate fume extraction.
Fire safety: Bismuth metal is not flammable, though fine powders may present combustion risks like other metal powders. Bismuth compounds are generally non-combustible.
Storage: Store bismuth and its compounds in cool, dry conditions. No special containment requirements beyond normal chemical storage practices.
Low environmental impact: Bismuth is considered environmentally benign compared to other heavy metals. It doesn't bioaccumulate significantly in food chains.
Water solubility: Most bismuth compounds have very low water solubility, limiting environmental mobility and uptake by organisms.
Soil interactions: Bismuth binds strongly to soil particles and organic matter, preventing leaching into groundwater systems.
Biodegradation: While bismuth doesn't biodegrade (being an element), it also doesn't interfere significantly with biological processes in the environment.
Pregnancy and nursing: Bismuth compounds should be used during pregnancy only when clearly needed. Consult healthcare providers before use.
Children: Bismuth subsalicylate is not recommended for children under 12 due to salicylate content, not bismuth toxicity. Pure bismuth compounds are generally safe for children.
Elderly patients: No special precautions needed for bismuth use in elderly populations beyond normal medical supervision.
Kidney disease: While bismuth is rapidly excreted by kidneys, patients with severe kidney disease should use bismuth compounds under medical supervision.
Bismuth's excellent safety profile makes it an ideal green alternative to toxic heavy metals in many applications:
Quick answers
Bismuth (symbol Bi) is element 83 on the periodic table, a post-transition metal in period 6, group 15. The heaviest element that is very nearly stable, and the one that grows spectacular rainbow crystals. At room temperature it is a solid.
[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p³, giving 6 occupied shells holding 2, 8, 18, 32, 18, 5 electrons respectively. Its outer shell holds 5 electrons, which is what sets its bonding behaviour.Bismuth melts at 544.7 K (271.6 °C) and boils at 1837 K (1563.9 °C).
The standard atomic weight of Bismuth is 208.98 u. That is a weighted average across its naturally occurring isotopes, which is why it is rarely a whole number.
Bismuth has a density of 9.78 g/cm³. Water is 1.0 g/cm³, so a block of bismuth is about 9.8× heavier.
Bismuth has a Pauling electronegativity of 2.02. The scale runs from 0.70 (francium, the least greedy for electrons) to 3.98 (fluorine, the most). Values in this middle band tend to form covalent rather than strongly ionic bonds.
Bismuth was discovered in 1753 by Claude Francois Geoffroy. It is named after german weisse Masse, "white mass".
Bismuth makes up about 0.0085 mg/kg of the Earth's crust — genuinely rare, which is why it is expensive.
Technically yes, but only just. Bismuth-209 was shown in 2003 to undergo alpha decay with a half-life around 2×10¹⁹ years — about a billion times the age of the universe. For every practical purpose it behaves as a stable element, and it is routinely used as a non-toxic substitute for lead.