Bismuth
Atomic Data
| Atomic Number | 83 |
| Symbol | Bi |
| Atomic Weight | 208.98 u |
| Density (STP) | 9.747 g/cm³ |
| Melting Point | 271.4 °C (544.55 K) |
| Boiling Point | 1563.85 °C (1837 K) |
| Electronegativity | 2.02 (Pauling) |
| Electron Config. | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p3 |
| Oxidation States | +3, +5 |
| Phase at STP | Solid |
| Category | Post-Transition Metal |
| Period / Group | 6 / 15 |
| CAS Number | 7440-69-9 |
Electron Configuration
[Xe] 4f14 5d10 6s2 6p3
| Shell | n | Subshell | Electrons | Cumulative |
|---|---|---|---|---|
| K | 1 | 1s | 2 | 2 |
| L | 2 | 2s | 2 | 4 |
| L | 2 | 2p | 6 | 10 |
| M | 3 | 3s | 2 | 12 |
| M | 3 | 3p | 6 | 18 |
| M | 3 | 3d | 10 | 28 |
| N | 4 | 4s | 2 | 30 |
| N | 4 | 4p | 6 | 36 |
| N | 4 | 4d | 10 | 46 |
| N | 4 | 4f | 14 | 60 |
| O | 5 | 5s | 2 | 62 |
| O | 5 | 5p | 6 | 68 |
| O | 5 | 5d | 10 | 78 |
| P | 6 | 6s | 2 | 80 |
| P | 6 | 6p | 3 | 83 |
| Total | 83 | 83 | ||
Isotopes of Bismuth
Bismuth is monoisotopic: ²⁰⁹Bi is its only naturally occurring stable isotope, accounting for 100% of all natural Bismuth.
| Isotope | Symbol | Protons | Neutrons | Abundance | Stability |
|---|---|---|---|---|---|
| Bismuth-209 | ²⁰⁹Bi | 83 | 126 | 100 | Stable |
Abundance & Occurrence
Bismuth is present in Earth's crust at approximately 0.025 ppm by mass and at approximately 0.007 ppm by mass throughout the universe.
Earth's Crust (ppm by mass)
Universe (ppm by mass)
Discovery & History
Read more about the discovery of the periodic table of elements →
Safety & Handling
- Low acute toxicity: Bismuth metal and bismuth subsalicylate have low acute toxicity; bismuth compounds have been used medicinally for over a century (Pepto-Bismol) and are generally considered safe at therapeutic doses.
- Bismuth encephalopathy: Excessive bismuth intake: historically from high-dose bismuth subnitrate or subgallate used as gut astringents: has caused bismuth encephalopathy (confusion, tremor, myoclonus) in elderly patients; the condition is reversible on stopping bismuth.
- Kidney effects: Very high-dose exposure to soluble bismuth salts can cause kidney damage; bismuth trichloride and other reactive compounds are corrosive and should be handled with appropriate PPE.
- Radioactive decay: Natural bismuth-209 is very slightly radioactive (t½ ≈ 1.9 × 1019 years); its activity is so low that it poses no radiation hazard under any practical handling conditions.
Bismuth in the Real World
Real-World Uses
- Pharmaceuticals (gastrointestinal): Bismuth subsalicylate (Pepto-Bismol) treats nausea, heartburn, indigestion, and traveller's diarrhoea; bismuth salts (tripotassium dicitratobismuthate) are used with antibiotics to eradicate Helicobacter pylori bacteria that cause peptic ulcers.
- Low-melting fusible alloys: Bismuth forms low-melting alloys (Wood's metal, Field's metal) with tin, lead, indium, and cadmium; these are used in fire sprinkler system fusible links, safety plugs in compressed gas cylinders, and casting tools for benchwork.
- Cosmetics (pearlescent effect): Bismuth oxychloride (BiOCl) produces the shimmery, metallic pearlescent effect in blushers, eye shadows, highlighters, and nail polish, and is a non-toxic alternative to older metallic pigments.
- Lead-free ammunition and fishing weights: Bismuth shot and sinkers are used as a non-toxic alternative to lead in waterfowl hunting and fishing, where lead poisoning of birds and aquatic life from ingested pellets and weights is a regulatory concern.
- Thermoelectric materials: Bismuth telluride (Bi₂Te₃) is the standard thermoelectric material at near-ambient temperatures, used in Peltier coolers for electronic thermal management, portable refrigerators, and seat cooling systems.
Downloadable Resources
Free periodic table reference sheets for classrooms, study sessions, and laboratory use.
Frequently Asked Questions
What is bismuth used for?
Bismuth's largest use is in pharmaceuticals: bismuth subsalicylate is the active ingredient in Pepto-Bismol, used for nausea, heartburn, and diarrhoea. Bismuth compounds are used as a replacement for lead in lead-free solders, low-melting alloys (such as Wood's metal), and in shotgun pellets (replacing toxic lead shot). Bismuth oxychloride is used as a pearlescent pigment in cosmetics.
Is bismuth the heaviest stable element?
Bismuth (Z=83) was long considered the heaviest stable element. However, in 2003 it was discovered that bismuth-209: the only natural isotope: is very slightly radioactive, decaying by alpha emission with a half-life of 2.01 × 10^19 years, over a billion times the age of the universe. Bismuth is therefore technically radioactive but so slowly that it is entirely safe and effectively stable for all practical purposes.
How was bismuth discovered?
Bismuth was known in antiquity and often confused with lead, tin, or antimony. It was recognised as a distinct metal in the 15th century. The French chemist Claude François Geoffroy demonstrated in 1753 that bismuth was a distinct element rather than a form of lead. Its name may derive from the German 'Weisse Masse' (white mass) or from an Arabic word, via Latin 'bisemutum'.
Why is bismuth replacing lead in many applications?
Bismuth has a density close to lead (9.8 g/cm3 vs 11.3 g/cm3) and is relatively non-toxic, making it a practical substitute in many applications where lead is being phased out due to its toxicity. Bismuth-tin alloys are used as lead-free solders, bismuth shot is used instead of lead shot for waterfowl hunting (which was banned partly because waterfowl swallow spent pellets), and bismuth alloys are used in low-melting fusible alloys for safety devices such as fire sprinklers.