31 Properties of Bismuth (Facts You Don’t Know!)

Bismuth (Bi), atomic number 83, density 9.78 g/cm³, melting point 271.3°C. It’s the most diamagnetic element, with low thermal conductivity. Notable for its low toxicity and use in cosmetics, pharmaceuticals, and alloys. Bi-209 is stable, but Bi-209 decays to Th-205 with a half-life of >1.9×10¹⁹ years.

Basic Properties of Bismuth

Property	Value
Atomic Number	83
Atomic Mass	208.98040 u
State at Room Temperature	Solid
Density	9.78 g/cm3
Number of Electrons	83
Number of Protons	83
Number of Neutrons	126
Period	6
Group	15
Discovery	Ancient times, commonly occurring as a free element
Cost	~$5/lb (2022)

Bismuth is a post-transition metal with unique electrical, optical, and thermal properties. It has a lustrous silver appearance with a rhombohedral crystalline structure. Bismuth displays diamagnetism and has the lowest thermal conductivity of any metal.

Image Credit: Bismuth crystal by Alchemist-hp,Richard Bartz, further modifications by Poke2001

Bismuth Physical Properties

Property	Value
Melting Point	271.3°C
Boiling Point	1560°C
Solubility in Water	Insoluble
Electrical Conductivity	1 x 10^6 S/m
Magnetism	Diamagnetic
Color	Silver, reddish tinge
Odor	Odorless
Hardness	2.5 Mohs
Vapor Pressure	1 mm Hg at 817°C
Viscosity	N/A
Surface Tension	N/A
Refractive Index	N/A
Specific Heat Capacity	0.122 J/g°C
Coefficient of Thermal Expansion	13 x 10^-6/°C

Bismuth has unusually low thermal and electrical conductivity compared to metals. It expands significantly during solidification, resulting in crisp details for castings. Bismuth compounds are often vibrantly colorful.

Bismuth Chemical Properties

Property	Value
Reactivity	Low, oxide layer forms in air
Flammability	Non-flammable
pH	N/A
Oxidation States	+3, +5
Electronegativity	2.02
Corrosion Resistance	Good, passivation layer forms
Chemical Stability	Stable in dry air
Heat of Combustion	N/A
Rate of Reaction	Slow reactant
Acid-Base Behavior	Amphoteric (can act as acid or base)
Redox Potential	-0.13V (Bi^3+/Bi)

Bismuth reacts slowly with oxygen and water vapor. It forms bismuth(III) oxide as a protective layer, providing good corrosion resistance. Bismuth compounds demonstrate significant photoconductivity.

Spectroscopic Properties of Bismuth

Property	Value
Absorption Wavelengths	300 – 600 nm
Emission Wavelengths	1000 – 1700 nm (near IR)
NMR Frequencies	-296 ppm (Bi-209)

Bismuth and its compounds absorb visible light and emit infrared photons. This property is useful for optical filters, detectors, and fiber optic communications.

Crystallographic Properties of Bismuth

Property	Value
Crystal Structure	Rhombohedral
Lattice Constants	a = 4.5465 Å, c = 11.8597 Å
Coordination Number	6
Point Group	-3m (C3i)

The rhombohedral unit cell of bismuth contains 2 atoms. It can be described as a distorted simple cubic lattice. Bismuth crystals demonstrate electrical resistance anisotropy.

Bismuth Electronic Properties

Property	Value
Band Gap	15-25 meV
Electrical Resistivity	106-108 nΩ⋅m
Electron Mobility	400-1050 cm^2/V⋅s
Effective Mass	0.001-0.26 m_e

Bismuth is a semimetal with a very small overlapping conduction and valence band. It has 100x higher resistance than copper. The low effective mass and high mobility of electrons in bismuth have applications in thermoelectric devices.

Bismuth Isotopic Composition

Isotope	Natural Abundance (%)	Half-life	Decay Mode
209Bi	100	Stable	N/A
208Bi	Synthetic	3.68E+5 years	β-decay to 208Pb
210Bi	Trace (from decay of 238U)	5.012 days	β-decay to 210Po
207Bi	Synthetic	31.55 years	β-decay to 207Pb

Bismuth Discovery Details

Property	Detail
Discoverer	Claude François Geoffroy
Year	1753
Origin of Name	From the German word “Weisse Masse” meaning white mass, later adapted to “Bismuth”

Interesting Facts on Bismuth

Fact	Detail
Low Thermal Conductivity	7.97 W/(m·K) at 300K, making it useful in thermal interfaces
High Electron Mobility	1.8 m^2/(V·s), facilitating its use in semiconductors
Unique Crystalline Structure	Rhombohedral lattice structure contributes to its low melting point and high brittleness
Non-toxic Alternative	Used as a non-toxic replacement for lead in various applications
Diamagnetic Properties	Strong diamagnetic properties, useful in magnetic levitation experiments

Applications and Uses of Bismuth

Application Category	Specific Applications	Details
Industrial Uses	Alloys, Fire Safety, Soldering	Low melting point alloys, fire detection systems, lead-free solders
Medical Uses	Pepto-Bismol, Radiotherapy	Used in gastrointestinal treatments, radiopaque shield in radiotherapy
Agricultural Uses	Pesticides	Bismuth compounds as fungicides and snail repellents
Energy Production	Thermoelectric Materials	Bismuth telluride used in thermoelectric cooling and power generation
Technology and Electronics	Semiconductors, Data Storage	High mobility semiconductors, phase-change memory components
Environmental Applications	Pollution Control, Lead Replacement	Bismuth compounds in heavy metal pollutant immobilization, non-toxic alternative to lead in fishing weights

Safety Precautions for Bismuth

Precaution Category	Precaution Details	Implementation
Handling	Wear protective equipment	Gloves, goggles, and lab coat to prevent skin and eye contact
Inhalation	Ensure adequate ventilation	Use fume hoods or respirators in areas of high dust concentration
Ingestion	Avoid eating or drinking in lab	Implement strict hygiene practices to avoid accidental ingestion
Environmental Precautions	Prevent release to environment	Collect spillages to prevent contamination, dispose of waste responsibly
Storage	Store in a cool, dry, well-ventilated area	Separate from incompatible materials such as strong acids and bases

References: www.rsc.org, britannica, wikipedia