Bismuth
Bismuth is a brittle, silvery-white metal with a faint pinkish tinge, best known outside chemistry labs for the strikingly colorful, geometric crystals it forms and for its role in the pink stomach-soothing medicine many people have in their medicine cabinet. For centuries it was confused with lead and tin, and it took careful experimentation to prove it was really its own distinct element.
- Group · Period
- 15 · 6
- At room temp
- solid
- Melts at
- 544.55 K
- Density
- 9.807 g/cm³
- Discovered
- 1753
Uses
Bismuth’s low toxicity compared to other heavy metals has made it a popular replacement for lead in several applications, including fishing weights, shotgun pellets, and some plumbing fixtures, where regulations increasingly restrict lead. It’s also alloyed into low-melting-point metals used in fire sprinkler triggers, fuses, and specialty solders, since adding bismuth can lower an alloy’s melting point dramatically. In medicine, bismuth subsalicylate is the active ingredient in well-known over-the-counter stomach remedies that treat indigestion, nausea, and diarrhea.
Bismuth oxychloride, a compound that produces a soft, pearly shimmer, is also widely used as a pigment in cosmetics like eyeshadow and nail polish, and bismuth’s naturally colorful crystal formations have made it a popular subject for hobbyist crystal growing.
History
Bismuth had been mined and used since medieval times, but for centuries it was frequently confused with lead, tin, and even antimony, since early metallurgists lacked the tools to tell chemically similar-looking metals apart. In 1753, French chemist Claude François Geoffroy carried out experiments that clearly distinguished bismuth’s properties from those of lead, establishing it as a genuinely separate element. Its name is generally thought to trace back to old German mining terms, though its exact origins are less certain than those of many other elements from the same era.
Fun facts
- Bismuth is one of the very few metals that expands as it solidifies from a liquid, a rare property it shares with water.
- Hand-grown bismuth crystals form colorful, stair-step geometric patterns caused by a thin oxide layer that interferes light into rainbow colors, similar to how a soap bubble looks.
- Bismuth is the active ingredient in bismuth subsalicylate, the compound behind the pink stomach-relief medicine sold under brand names like Pepto-Bismol.
Frequently asked questions
Why do bismuth crystals look so colorful and geometric?
When molten bismuth cools, it grows in a distinctive stair-step, hopper-crystal pattern because it solidifies faster along the edges than the faces. A very thin layer of oxide forms on the surface as it cools, and that thin film bends light in a way that produces the swirling rainbow colors, the same basic effect you see in a soap film or an oil slick.
Is bismuth toxic like lead?
No — bismuth is generally considered one of the least toxic heavy metals, which is exactly why it's used in stomach medicine and why it's become a popular substitute for lead in products like fishing weights, ammunition, and some solders where lead was once standard.
Was bismuth really mistaken for other metals?
Yes, for a long time miners and early chemists lumped bismuth in with lead and tin because it looks and behaves somewhat similarly as a soft, low-melting metal. It wasn't until 1753 that careful chemical experiments clearly showed bismuth was a separate element rather than a form of one of those more familiar metals.
Compounds
5 notable compounds containing Bi
- BiOClpigment
Bismuth oxychloride
A pearly white powder built from stacked layers that scatter light with a soft, nacre-like shimmer, giving it an optical effect similar to ground mother-of-pearl.
Used for: Pearlescent shimmer pigment in cosmetics such as eyeshadow and foundation
- C7H5BiO4pharmaceutical
Bismuth subsalicylate
A pale yellow, water-insoluble organobismuth compound that coats and soothes the stomach lining while its salicylate portion provides mild anti-inflammatory action.
Used for: Active ingredient in over-the-counter upset-stomach remedies like Pepto-Bismol
- Bi2Te3semiconductor
Bismuth telluride
A gray, layered crystalline semiconductor whose electrons carry heat and charge in a way that makes it the most efficient known material for converting small temperature differences directly into electricity near room temperature.
Used for: Peltier coolers and thermoelectric power generators
- BiCl3salt
Bismuth trichloride
A moisture-sensitive white solid that fumes in humid air as it hydrolyzes, and acts as a comparatively gentle, low-toxicity Lewis acid in organic chemistry.
Used for: Lewis acid catalyst in organic synthesis
- Bi2O3oxide
Bismuth trioxide
A pale yellow solid and the most important commercial bismuth compound, serving as the starting point from which nearly all other bismuth chemicals are produced.
Used for: Precursor for bismuth chemicals and ingredient in ceramic glazes and electroceramics
Isotopes
41 known isotopes
Swipe to see all columns →
| Isotope | Natural abundance | Half-life | Decay mode | Mass excess | Binding energy / nucleon | Decay width |
|---|---|---|---|---|---|---|
| Bi-209 | 100% | 2.01E19 Y | Alpha decay (100%) | -18,258.59 keV | 7,847.99 keV | 7.19 × 10-43 eV |
Show all 41 isotopes
| Bi-184 | — | 13 ms | Alpha decay (100%) | 1,254 keV | 7,712 keV | 3.51 × 10-14 eV |
| Bi-185 | — | 58 us | Proton emission (90%), Alpha decay (10%) | -2,236 keV | 7,732 keV | 7.87 × 10-12 eV |
| Bi-186 | — | 14.8 ms | Alpha decay (95.5%), Electron capture / beta-plus decay (4.5%), SF+EC+B+ (0.02%) | -3,145.5 keV | 7,739.12 keV | 3.08 × 10-14 eV |
| Bi-187 | — | 37 ms | Alpha decay (100%) | -6,383.28 keV | 7,758.21 keV | 1.23 × 10-14 eV |
| Bi-188 | — | 60 ms | Alpha decay (100%) | -7,194.8 keV | 7,764.19 keV | 7.60 × 10-15 eV |
| Bi-189 | — | 688 ms | Alpha decay (100%) | -10,064.66 keV | 7,781 keV | 6.63 × 10-16 eV |
| Bi-190 | — | 6.3 s | Alpha decay (90%), Electron capture / beta-plus decay (10%), SF+EC+B+ (0.000023%) | -10,595.91 keV | 7,785.32 keV | 7.24 × 10-17 eV |
| Bi-191 | — | 12.4 s | Alpha decay (51%), Electron capture / beta-plus decay (49%) | -13,239.35 keV | 7,800.66 keV | 3.68 × 10-17 eV |
| Bi-192 | — | 34.6 s | Electron capture / beta-plus decay (88%), Alpha decay (12%) | -13,534.54 keV | 7,803.61 keV | 1.32 × 10-17 eV |
| Bi-193 | — | 63.6 s | Electron capture / beta-plus decay (96.5%), Alpha decay (3.5%) | -15,884.56 keV | 7,817.17 keV | 7.17 × 10-18 eV |
| Bi-194 | — | 95 s | Electron capture / beta-plus decay (99.54%), Alpha decay (0.46%) | -16,023.02 keV | 7,819.2 keV | 4.80 × 10-18 eV |
| Bi-195 | — | 183 s | Electron capture / beta-plus decay (99.97%), Alpha decay (0.03%) | -18,025.57 keV | 7,830.76 keV | 2.49 × 10-18 eV |
| Bi-196 | — | 308 s | Electron capture / beta-plus decay (100%), Alpha decay (0.00115%) | -18,009.03 keV | 7,831.9 keV | 1.48 × 10-18 eV |
| Bi-197 | — | 9.33 m | Electron capture / beta-plus decay (100%), Alpha decay (0.0001%) | -19,687.2 keV | 7,841.63 keV | 8.15 × 10-19 eV |
| Bi-198 | — | 10.3 m | Electron capture / beta-plus decay (100%) | -19,373.85 keV | 7,841.21 keV | 7.38 × 10-19 eV |
| Bi-199 | — | 27 m | Electron capture / beta-plus decay (100%) | -20,797.62 keV | 7,849.52 keV | 2.82 × 10-19 eV |
| Bi-200 | — | 36.4 m | Electron capture / beta-plus decay (100%) | -20,370.57 keV | 7,848.5 keV | 2.09 × 10-19 eV |
| Bi-201 | — | 103 m | Electron capture / beta-plus decay (100%) | -21,429.01 keV | 7,854.87 keV | 7.38 × 10-20 eV |
| Bi-202 | — | 1.71 h | Electron capture / beta-plus decay (100%) | -20,750.85 keV | 7,852.59 keV | 7.41 × 10-20 eV |
| Bi-203 | — | 11.76 h | Electron capture / beta-plus decay (100%) | -21,524.89 keV | 7,857.48 keV | 1.08 × 10-20 eV |
| Bi-204 | — | 11.22 h | Electron capture / beta-plus decay (100%) | -20,645.93 keV | 7,854.22 keV | 1.13 × 10-20 eV |
| Bi-205 | — | 14.91 d | Electron capture / beta-plus decay (100%) | -21,065.57 keV | 7,857.32 keV | 3.54 × 10-22 eV |
| Bi-206 | — | 6.243 d | Electron capture / beta-plus decay (100%) | -20,028.2 keV | 7,853.32 keV | 8.46 × 10-22 eV |
| Bi-207 | — | 31.55 Y | Electron capture / beta-plus decay (100%) | -20,054.55 keV | 7,854.51 keV | 4.58 × 10-25 eV |
| Bi-208 | — | 3.68E+5 Y | Electron capture / beta-plus decay (100%) | -18,870.15 keV | 7,849.85 keV | 3.93 × 10-29 eV |
| Bi-210 | — | 5.012 d | Beta-minus decay (100%), Alpha decay (0.000132%) | -14,791.91 keV | 7,832.54 keV | 1.05 × 10-21 eV |
| Bi-211 | — | 2.14 m | Alpha decay (99.724%), Beta-minus decay (0.276%) | -11,859.12 keV | 7,819.77 keV | 3.55 × 10-18 eV |
| Bi-212 | — | 60.55 m | Beta-minus decay (64.06%), Alpha decay (35.94%) | -8,117.94 keV | 7,803.31 keV | 1.26 × 10-19 eV |
| Bi-213 | — | 45.59 m | Beta-minus decay (97.86%), Alpha decay (2.14%) | -5,231.67 keV | 7,791.02 keV | 1.67 × 10-19 eV |
| Bi-214 | — | 19.71 m | Beta-minus decay (99.979%), Alpha decay (0.021%), Beta-minus, alpha emission (0.003%) | -1,200.78 keV | 7,773.5 keV | 3.86 × 10-19 eV |
| Bi-215 | — | 7.6 m | Beta-minus decay (100%) | 1,629.27 keV | 7,761.72 keV | 1.00 × 10-18 eV |
| Bi-216 | — | 2.25 m | Beta-minus decay (100%) | 5,873.99 keV | 7,743.5 keV | 3.38 × 10-18 eV |
| Bi-217 | — | 98.5 s | Beta-minus decay (100%) | 8,729.96 keV | 7,731.85 keV | 4.63 × 10-18 eV |
| Bi-218 | — | 33 s | Beta-minus decay (100%) | 13,216.04 keV | 7,712.83 keV | 1.38 × 10-17 eV |
| Bi-219 | — | 22 s | Beta-minus decay (100%) | 16,320 keV | 7,700 keV | 2.07 × 10-17 eV |
| Bi-220 | — | 300 ns | Beta-minus decay | 20,960 keV | 7,681 keV | 1.52 × 10-9 eV |
| Bi-221 | — | 300 ns | Beta-minus, neutron emission, Beta-minus decay | 24,200 keV | 7,668 keV | 1.52 × 10-9 eV |
| Bi-222 | — | 300 ns | Beta-minus, neutron emission, Beta-minus decay | 28,950 keV | 7,648 keV | 1.52 × 10-9 eV |
| Bi-223 | — | 300 ns | Beta-minus, neutron emission, Beta-minus decay | 32,240 keV | 7,636 keV | 1.52 × 10-9 eV |
| Bi-224 | — | — | Beta-minus decay (100%), Beta-minus, neutron emission | 37,070 keV | 7,616 keV | — |