Category: Metalloid
Atomic Number: 51
Period: 5 | Group: 15
Block: p-block
A brittle metalloid used since antiquity as eye cosmetic, and now as a flame retardant.
| Property | Value |
|---|---|
| Phase at STP | Solid |
| Density | N/A |
| Melting Point | 903.78 K (630.63 °C) |
| Boiling Point | 1860.00 K (1586.85 °C) |
| Heat Capacity | N/A |
| Property | Value |
|---|---|
| Atomic Mass | 121.7600 u |
| Electronegativity (Pauling) | N/A |
| Oxidation States | -3, +3, +5 |
| Electron Configuration |
| Discovered By | Unknown |
|---|---|
| Discovery Year | Ancient |
| Named After | Greek anti + monos; symbol from stibium |
Ancient Beauty Secret to Modern Element
Ancient Egyptian Origins (3000 BCE)
Antimony's story begins with ancient beauty rituals . Egyptian queens, including Cleopatra, used ground stibnite (antimony sulfide) as "kohl" - dramatic black eye makeup that also protected against eye infections and glare from desert sun.
Medieval Alchemy
Medieval alchemists called antimony "the wolf of metals" because it seemed to "devour" other metals when heated together. The symbol ♁ represented antimony in alchemical texts, and practitioners believed it held transmutation powers.
The Monk's Mysterious Discovery
Around 1450, a German Benedictine monk named Basil Valentine (possibly a pseudonym) wrote extensively about antimony in his manuscript "The Triumphal Chariot of Antimony." He described methods for extracting metallic antimony and its medical applications - though his treatments often proved toxic!
Noble Metal Confusion
For centuries, antimony was confused with lead and tin. The name comes from Greek "anti-monos" meaning "not alone" because it was rarely found in pure form. Arabic alchemists called it "al-ithmid," later corrupted to "antimony."
Scientific Recognition
Nicolas Lémery (1707) first clearly distinguished antimony as a distinct element in his chemical treatise. He demonstrated that antimony could be isolated as a brittle, silvery metal with unique properties different from lead or tin.
Industrial Revolution Applications
The Industrial Revolution revealed antimony's true potential:
1780s: Type metal alloys for printing presses transformed publishing
1840s: Antimony in friction matches and percussion caps
1860s: Britannia metal (antimony-tin alloy) for decorative items
1890s: Lead-antimony battery grids developed for early automobiles
20th Century Flame Retardants
1950s Discovery: Scientists discovered that antimony trioxide dramatically enhanced the flame-retardant properties of halogenated compounds. This breakthrough led to antimony's most important modern application - saving countless lives through fire prevention.
Modern Understanding
Today we understand antimony as a metalloid with unique properties:
Electron Configuration: [Kr] 4d¹⁰ 5s² 5p³
Allotropy: Exists in multiple crystalline forms
Semiconductor Properties: Used in modern electronics and infrared detectors
Journey: From Cleopatra's eye makeup to modern fire safety - antimony's 5,000-year journey shows how ancient materials can find new purposes through scientific understanding!
| ISOTOPE | Neutrons | Natural Abundance | Half-life | Decay Mode |
|---|---|---|---|---|
| Sb-121 | 70 | 57.21% | Stable | - |
| Sb-123 | 72 | 42.79% | Stable | - |
Data: IAEA Nuclear Data Section, LiveChart of Nuclides, ground-state evaluations, retrieved October 10, 2026. Abundance is the share of atoms in the natural element; a dash means the isotope has no standard natural abundance.
Fire Safety & Flame Retardants
Antimony trioxide (Sb₂O₃) is the world's most important flame retardant synergist, one of the two largest uses of antimony (36% of U.S. primary antimony consumption in 2022). It works by releasing antimony halides that interfere with combustion chemistry, protecting everything from children's pajamas to aircraft interiors.
Automotive Industry
Brake Pads: Antimony sulfide provides friction material that performs consistently at high temperatures
Battery Grids: Lead-antimony alloys (2-6% Sb) in car batteries provide mechanical strength and corrosion resistance
Bearing Alloys: Antimony-tin-copper Babbitt metals for heavy-duty engine bearings
Soldering: Antimony in lead-free solders for automotive electronics
Glass & Ceramics
Glass Clarification: Antimony trioxide removes bubbles and improves clarity in high-quality glass production
Decolorizing Agent: Neutralizes yellow and green tints caused by iron impurities in glass
Opacifying Agent: Creates white, opaque glass and ceramic glazes
Television Screens: Antimony compounds in cathode ray tube glass for radiation shielding
Textiles & Plastics
Polyester Production: Antimony catalysts (antimony trioxide) enable polyethylene terephthalate (PET) polymerization
Flame-Retardant Fabrics: Antimony compounds in carpets, upholstery, and protective clothing
Plastic Additives: Antimony trioxide combined with halogenated compounds in rigid PVC and thermoset plastics
Pigments & Paints
Naples Yellow: Lead antimonate creates this historic artistic pigment used since ancient times
Camouflage Paints: Antimony compounds reduce infrared reflectance for military applications
Ceramic Glazes: Antimony creates yellow and white colors in pottery and tiles
Electronics & Semiconductors
Semiconductor Doping: Ultra-pure antimony as n-type dopant in silicon and germanium
Thermoelectric Devices: Bismuth-antimony alloys for Peltier cooling systems
Infrared Detectors: Indium antimonide (InSb) for military and scientific applications
Diodes: Antimony compounds in tunnel diodes and microwave devices
Military & Defense
Tracer Ammunition: Antimony compounds create visible bullet trajectories
Primer Compositions: Antimony trisulfide in percussion caps and small arms primers
Armor Piercing: Antimony hardens lead cores in armor-piercing projectiles
Pharmaceutical Applications
Antiparasitic Drugs: Antimony compounds treat leishmaniasis and schistosomiasis
Veterinary Medicine: Antimony potassium tartrate for treating certain animal parasites
| Earth's Crust | N/A |
|---|---|
| Universe | N/A |