Atomic number 83

Bismuth

Bi
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− phase

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83 electrons in 6 shells: 2, 8, 18, 32, 18, 5.

Shells are a teaching model: an electron does not travel on a ring at a fixed distance.

Category: Post-transition metal
Period: 6
Group: 15
Block: p
Standard atomic weight: 208.98(1) Da
Electron configuration: [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p³
Phase at 25 °C: solid
Melting point: 271.5 °C
Boiling point: 1564 °C
Density: 9.807 g/cm³
Electronegativity (Pauling): 2.02
Discovered: 1753, shown distinct from lead; the metal itself was known in ancient times, Claude Geoffroy the Younger

Neighbours in the table

A broken lump of bismuth shows a white, crystalline face with a pinkish tinge, and the metal shatters where most metals bend. OpenStax counts malleability and good conduction of heat among the marks of a metallic solid. Los Alamos describes bismuth as brittle, and says its thermal conductivity is lower than that of any metal except mercury.

A magnet reveals two further oddities. Los Alamos reports the largest Hall effect of any metal: in a magnetic field, bismuth’s electrical resistance climbs more than any other metal’s. It also calls bismuth the most diamagnetic of all metals, diamagnetic meaning that an applied field induces a weak field pointing the other way.

The configuration ends [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p³, five valence electrons in the sixth shell. Active nonmetals take three of them readily, leaving Bi³⁺. The group’s +5 oxidation state, a bookkeeping number, not a charge, needs strong oxidising agents, OpenStax says. OpenStax files the stable +3 state under the inert pair effect, with the 6s pair kept back. Heated in air, bismuth burns with a blue flame into yellow fumes of Bi₂O₃.

Where it is found

Bismuth is scarce: PubChem’s record gives 8.5 × 10⁻³ milligrams per kilogram of crust and 2 × 10⁻⁵ milligrams per litre of seawater. It turns up as native metal and in bismuthinite, Bi₂S₃, and bismite, Bi₂O₃, the two ores Los Alamos ranks first. Jefferson Lab’s text in the same record puts the largest deposits in Bolivia.

Its minerals seldom collect in amounts worth mining for themselves, so the US Geological Survey finds most bismuth recovered from lead ore. China and Vietnam also take it from tungsten ore, Japan and the Republic of Korea from zinc ore. The survey knows of two mines where bismuth was the main product: Bolivia’s Tasna Mine, idle since 1996, and one in China.

World refinery output was about 16,000 metric tons in 2024, 13,000 of it Chinese, with Laos at 1,100 and the Republic of Korea at 1,000. Los Alamos names Peru, Japan, Mexico, Bolivia and Canada as major producers instead. The United States stopped refining primary bismuth in 1997; imports, two-thirds from China over 2020–23, met 89 per cent of its 2024 needs.

Why it matters

The US Geological Survey presents bismuth as a nontoxic stand-in for lead: in brass, in free-machining steels and aluminium alloys, and in solders. Its use in plumbing brass grew after 2014, when the Safe Drinking Water Act’s meaning of lead-free cut the lead allowed in fixtures from 8 to 0.25 per cent. Fishing weights, hunting ammunition and lubricating greases take it in lead’s place as well.

The metal melts at 271.5 °C, and the survey ties its fusible alloys to uses where a low melting point is ideal. Such alloys plug abandoned oil wells, fill tubes temporarily so bending does not damage them, and trigger fire sprinklers. Jefferson Lab’s text adds electrical fuses. Liquid bismuth expands by 3.32 per cent as it solidifies, which Los Alamos says suits its alloys to sharp castings.

Most American bismuth goes into chemicals for cosmetic, industrial, laboratory and pharmaceutical use; Los Alamos notes heavy use of the oxychloride in cosmetics. Two short-lived isotopes, bismuth-212 and bismuth-213, ride on antibodies to cancer cells. IUPAC’s note says bismuth-213 mostly emits a beta particle, becoming polonium-213, whose alpha particle, carrying 8.4 MeV (million electronvolts) of energy, kills the cell. The IAEA table gives that branch 97.91 per cent and a direct alpha branch 2.09 per cent.

Properties

Properties of bismuth Standard atomic weights from IUPAC/CIAAW (abridged, 2024); other values from PubChem's periodic table, kelvin converted to °C.
Property	Value	Unit	Source
Atomic number	83
Standard atomic weight	208.98(1) Da	Da	IUPAC/CIAAW 2024
Melting point	271.5 °C	°C	Los Alamos: 271.5 °C
Boiling point	1564 °C	°C	Los Alamos: 1564 °C
Density	9.807 g/cm³	g/cm³
Electronegativity (Pauling)	2.02
Electron configuration	1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p³
Phase at 25 °C	solid

Safety

A bar or lump of bismuth is of low hazard in everyday handling, and Haz-Map, in PubChem’s record, calls the elemental metal nontoxic. Classifications differ: 324 of 382 company reports to the European Chemicals Agency (ECHA) find no hazard under the Globally Harmonized System (GHS). Japan’s 2009 classification instead marks it Danger for damage to organs, naming the nervous system, kidney and bone joints. The powder is flammable, and the PubChem Laboratory Chemical Safety Summary is the sheet for anyone working with it.

Questions

Is bismuth radioactive?

Only barely. Jefferson Lab's text in PubChem's record reports experiments in 2002 showing that bismuth-209, the one isotope found in nature, decays by alpha emission to thallium-205. Its half-life is roughly 1.9 × 10¹⁹ years in Jefferson Lab's figure and 2.01 × 10¹⁹ years in the IAEA Atomic Mass Data Center table. OpenStax adds that the neptunium decay series, once thought to end at bismuth-209, now ends at thallium-205.

What is bismuth used for in medicine?

Its compounds, not the metal, reach the pharmacy shelf. The US Geological Survey says bismuth subsalicylate is what does the work in stomach remedies sold without prescription, and lists bismuth compounds for burns, intestinal disorders and stomach ulcers. Jefferson Lab's text in PubChem's record gives bismuth carbonate, Bi₂(CO₃)₃, for diarrhoea and gastric ulcers. Los Alamos adds the subnitrate and subcarbonate, and pharmaceutical chemicals are part of most American bismuth consumption.

Who discovered bismuth?

The metal was known in ancient times and often confused with lead and tin, Jefferson Lab notes, so the credit goes to the chemist who proved it separate. In 1753 a French chemist showed it distinct from lead. Jefferson Lab calls him Claude Geoffroy the Younger; CIAAW gives Claude-Francois Geoffroy. The name comes from the German weisse Masse, white mass, which CIAAW links to the colour of its oxides.

What does bismuth have to do with polonium?

Marie Curie's new element kept company with bismuth: her electroscope showed it separating with that metal, Los Alamos records. In 1934 neutrons fired at natural bismuth-209 gave bismuth-210, the parent of polonium. IUPAC's note in PubChem's record has bismuth-210 turning into polonium-210 by beta decay. The IAEA table gives it a half-life of 5.012 days and adds a second, tiny branch: about 0.000132 per cent of its decays emit an alpha particle.