ChemSphere
83Bi208.98

Bismuth

Post-transition metal · Period 6 · Group 15 · p-block

The rainbow-crystal metal gentle enough to go in stomach medicine

Atomic mass
208.98 u
State at 25 °C
Solid
Electronegativity
2.02
Melting point
271.6 °C
Boiling point
1,563.9 °C
Configuration
[Xe] 4f14 5d10 6s2 6p3
Building atom…
83 protons 126 neutrons 83 electrons

Nucleus drawn at reduced count for clarity. Drag to rotate.

Bismuth, explained

Video lesson in production

Bhavya’s explainer for this element will play here.

Overview

Bismuth is a brittle, pinkish-silver metal at the bottom of group 15, below nitrogen, phosphorus, arsenic and antimony. Its outer electrons are 6s2 6p3, and as in thallium and lead, the 6s pair is held tightly, so bismuth usually loses only three electrons to form Bi3+. Unlike its toxic neighbours, bismuth and most of its compounds have low toxicity, partly because its salts are poorly absorbed from the gut. That makes it the one heavy metal routinely swallowed as medicine.

Bismuth has a puckered layered crystal structure that gives it unusual physical properties. It is the most strongly diamagnetic metal, pushed away by magnetic fields, and among the poorest metallic conductors of heat. Like water, it expands by about 3% when it freezes. When molten bismuth cools it forms stepped 'hopper' crystals, and a thin oxide film on their surface produces rainbow colours by thin-film interference. Its only natural isotope, bismuth-209, was shown in 2003 to be very weakly radioactive.

Discovery

Bismuth was known to medieval metalworkers but was often confused with lead and tin. The German mineralogist Georgius Agricola described it in the 1500s, and in 1753 Claude François Geoffroy showed that it was a distinct element. The name probably comes from the German wismut, possibly from weisse Masse ('white mass'), which was Latinised as bisemutum.

Where it’s found
Bismuth is a rare crust element, found occasionally native and in bismuthinite (Bi2S3), and is obtained mainly as a byproduct of lead, copper and tungsten refining.
What it’s used for
  • Stomach medicines
  • Lead-free solder
  • Fire sprinkler fusible links
  • Pearlescent cosmetics
  • Non-toxic shot
  • Yellow pigments
In living things
Bismuth has no biological role; it has low toxicity compared with neighbouring heavy metals, though large or prolonged doses can harm the kidneys and nervous system.
Safety
Bismuth metal is considered low-hazard, but its dust and some soluble compounds should not be inhaled or swallowed in quantity. Molten bismuth causes burns like any hot metal.

How it compares

Where Bismuth sits among all 118 elements on the trends that shape the table.

  • Electronegativity2.02Pauling

    #29 of 100 elements with data

  • Ionization energy703kJ/mol

    #49 of 104 elements with data

  • Atomic radius160pm

    #36 of 95 elements with data

  • Electron affinity90.9kJ/mol

    #33 of 109 elements with data

  • Density9.78g/cm³

    #42 of 114 elements with data

  • Melting point545K

    #81 of 110 elements with data

Density
9.78 g/cm³
Atomic radius
160 pm
Covalent radius
151 pm
Molar heat
25.52 J/(mol·K)
Appearance
lustrous silver
Discovered by
Claude François Geoffroy

Inside the atom

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

Orbital diagram

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p3 · shorthand [Xe] 4f14 5d10 6s2 6p3

  1. 1s2
  2. 2s2
  3. 2p6
  4. 3s2
  5. 3p6
  6. 4s2
  7. 3d10
  8. 4p6
  9. 5s2
  10. 4d10
  11. 5p6
  12. 6s2
  13. 4f14
  14. 5d10
  15. 6p3

Each box is an orbital holding up to two electrons of opposite spin. Highlighted subshells hold the valence electrons that decide how Bismuth bonds.

Ionization energies

Energy to remove each electron in turn, on a log scale. Each electron is harder to remove than the last, because the remaining ones feel more of the nucleus.

Signature reactions

The chemistry Bismuth is known for.

  1. Hydrolysis · Precipitation

    Hydrolysis of bismuth chloride

    Diluting a clear bismuth chloride solution makes it turn milky white as insoluble bismuth oxychloride forms. Adding acid reverses the change, and the same compound is used as a pearly pigment.

    BiCl3(aq)+H2O(l)BiOCl(s)+2HCl(aq)

    Conditions: diluting with water

  2. Redox · Combustion

    Burning bismuth

    Heated bismuth burns with a bluish flame to form yellow bismuth(III) oxide. Bismuth oxide is used in glass, ceramics and as an oxide-ion conductor in fuel-cell research.

    4Bi(s)+3O2(g)2Bi2O3(s)

    Conditions: strong heating in air

  3. Redox · Acid oxidation

    Dissolving in nitric acid

    Bismuth does not react with most non-oxidising acids, but nitric acid oxidises it to Bi3+ while being reduced to nitric oxide. Bismuth nitrate is the usual starting point for making other bismuth compounds.

    Bi(s)+4HNO3(aq)Bi(NO3)3(aq)+NO(g)+2H2O(l)

    Conditions: dilute nitric acid, warm

Where you’ll meet it

  • Hopper crystal

    Hopper crystal

    Lab-grown bismuth forms stepped hopper crystals whose oxide film shimmers with interference colours.

    Photo: Wikimedia Commons
  • Bismuthinite

    Bismuthinite

    Bismuthinite, bismuth sulfide, is the most important bismuth ore mineral.

    Photo: Wikimedia Commons
  • Wood's metal

    Wood's metal

    Wood's metal, about half bismuth, melts at roughly 70 °C, below the boiling point of water.

    Photo: Wikimedia Commons
  • Fire sprinkler

    Fire sprinkler

    Many sprinkler heads use a link of low-melting bismuth alloy that melts in a fire to release water.

    Photo: Wikimedia Commons

Research

No research on Bismuth yet

When Bhavya publishes a project that studies Bismuth, it will be linked here.

See all research