Antimony
Antimony is a brittle, silvery metalloid that has been used since ancient times, most famously as a dark eye cosmetic ground from its natural mineral form. It sits chemically between metals and nonmetals, and today it's best known for hardening lead alloys and as a flame-retardant additive in plastics and textiles.
- Group · Period
- 15 · 5
- At room temp
- solid
- Melts at
- 903.78 K
- Density
- 6.685 g/cm³
- Discovered
- Ancient
Uses
Antimony’s most common modern use is as a hardening agent for lead: alloyed together, the mixture is stiffer and more durable than pure lead, which makes it valuable for the grids inside lead-acid batteries, for cast bullets, and historically for the type metal used in printing presses. Antimony trioxide, a compound made from the element, is also one of the most widely used flame-retardant additives, mixed into plastics, textiles and electronic housings to make them resist catching fire.
Antimony compounds have a much older history as well — stibnite, the natural mineral form of antimony sulfide, was ground into the dark kohl eyeliner worn in ancient Egypt and other early civilizations, one of the earliest documented cosmetic uses of any element.
History
Antimony has no single discoverer, since its compounds, especially the mineral stibnite, were recognized and used by ancient civilizations long before the idea of a chemical element existed. Egyptian, Mesopotamian and other early cultures used antimony sulfide as a cosmetic and in early metal alloys, and by the medieval period alchemists were experimenting with it extensively. Its chemical symbol, Sb, comes from stibium, the Latin name tied to that same ancient mineral, a naming pattern shared with a handful of other elements whose everyday names and symbols come from different linguistic roots.
Fun facts
- Ancient Egyptians ground the mineral stibnite, a natural antimony compound, into the dark kohl eyeliner used for thousands of years.
- Adding antimony to lead makes it noticeably harder, which is why the alloy is used for battery plates, bullets and, historically, printing type.
- Antimony trioxide is one of the most widely used flame-retardant additives in plastics, textiles and electronics casings.
Frequently asked questions
Is antimony toxic like some other heavy elements?
Many antimony compounds are toxic in significant doses, similar in that respect to arsenic and other elements near it on the periodic table, so it's handled with care industrially. That said, antimony sulfide was used directly on the skin as kohl eyeliner in the ancient world, an illustration of how differently exposure levels and specific compounds can behave compared with pure or concentrated forms.
Why does antimony's symbol, Sb, not match its name?
Its symbol comes from stibium, the Latin name for the mineral stibnite that antimony was traditionally extracted from and used in. Antimony is one of several elements, along with iron, gold, sodium and a few others, whose modern names diverged from the older Latin terms their chemical symbols still preserve.
Why is antimony added to lead?
Pure lead is quite soft, which limits how it can be used. Alloying it with a small amount of antimony makes it noticeably harder and more rigid without losing lead's other useful properties, which is why antimony-lead alloys are used for things like battery grids and cast bullets that need to hold their shape.
Compounds
5 notable compounds containing Sb
- SbCl5halide
Antimony pentachloride
A yellow, fuming liquid and powerful Lewis acid that hydrolyzes readily in moist air, used to catalyze chlorination reactions.
Used for: Catalyst for chlorination and polymerization reactions
- SbCl3halide
Antimony trichloride
A white, fuming solid known historically as "butter of antimony," used as a chlorinating agent and Lewis acid catalyst in organic synthesis.
Used for: Catalyst and intermediate in organic and dye chemistry
- Sb2O3oxide
Antimony trioxide
A white powder and antimony's most important commercial compound, prized as a synergist that boosts the effectiveness of halogenated flame retardants.
Used for: Flame-retardant synergist in plastics and textiles
- InSbsemiconductor
Indium antimonide
A narrow-bandgap III-V semiconductor crystal that responds strongly to infrared light, especially when cooled to cryogenic temperatures.
Used for: Infrared detectors and thermal imaging sensors
- Sb2S3mineral
Stibnite
A lustrous, metallic gray mineral and the principal ore of antimony, long used in the ancient world as a dark eye cosmetic known as kohl.
Used for: Primary ore of antimony metal; historic cosmetic pigment
Isotopes
40 known isotopes
Swipe to see all columns →
| Isotope | Natural abundance | Half-life | Decay mode | Mass excess | Binding energy / nucleon | Decay width |
|---|---|---|---|---|---|---|
| Sb-121 stable | 57.21% | Stable | — | -89,599.16 keV | 8,482.06 keV | — |
| Sb-123 stable | 42.79% | Stable | — | -89,222.89 keV | 8,472.32 keV | — |
Show all 40 isotopes
| Sb-103 | — | 49 ns | Proton emission | -56,670 keV | 8,234 keV | 9.31 × 10-9 eV |
| Sb-104 | — | 0.44 s | Electron capture / beta-plus decay (100%), ECP (7%), Proton emission (1%) | -59,295 keV | 8,258 keV | 1.04 × 10-15 eV |
| Sb-105 | — | 1.22 s | Electron capture / beta-plus decay (100%), Proton emission | -64,015.49 keV | 8,300.99 keV | 3.74 × 10-16 eV |
| Sb-106 | — | 0.6 s | Electron capture / beta-plus decay | -66,473.3 keV | 8,322.01 keV | 7.60 × 10-16 eV |
| Sb-107 | — | 4.0 s | Electron capture / beta-plus decay (100%) | -70,653.25 keV | 8,358.73 keV | 1.14 × 10-16 eV |
| Sb-108 | — | 7.4 s | Electron capture / beta-plus decay (100%) | -72,445.34 keV | 8,372.67 keV | 6.17 × 10-17 eV |
| Sb-109 | — | 17.2 s | Electron capture / beta-plus decay (100%) | -76,250.99 keV | 8,404.82 keV | 2.65 × 10-17 eV |
| Sb-110 | — | 23.6 s | Electron capture / beta-plus decay (100%) | -77,449.75 keV | 8,412.68 keV | 1.93 × 10-17 eV |
| Sb-111 | — | 75 s | Electron capture / beta-plus decay (100%) | -80,836.75 keV | 8,440.12 keV | 6.08 × 10-18 eV |
| Sb-112 | — | 53.5 s | Electron capture / beta-plus decay (100%) | -81,598.97 keV | 8,443.63 keV | 8.53 × 10-18 eV |
| Sb-113 | — | 6.67 m | Electron capture / beta-plus decay (100%) | -84,416.97 keV | 8,465.28 keV | 1.14 × 10-18 eV |
| Sb-114 | — | 3.49 m | Electron capture / beta-plus decay (100%) | -84,496.62 keV | 8,462.52 keV | 2.18 × 10-18 eV |
| Sb-115 | — | 32.1 m | Electron capture / beta-plus decay (100%) | -87,003.41 keV | 8,480.92 keV | 2.37 × 10-19 eV |
| Sb-116 | — | 15.8 m | Electron capture / beta-plus decay (100%) | -86,822.02 keV | 8,475.82 keV | 4.81 × 10-19 eV |
| Sb-117 | — | 2.80 h | Electron capture / beta-plus decay (100%), Beta-plus decay (1.7%) | -88,639.56 keV | 8,487.9 keV | 4.53 × 10-20 eV |
| Sb-118 | — | 3.6 m | Electron capture / beta-plus decay (100%) | -87,996.2 keV | 8,478.92 keV | 2.11 × 10-18 eV |
| Sb-119 | — | 38.19 h | Electron capture (100%) | -89,475.54 keV | 8,487.92 keV | 3.32 × 10-21 eV |
| Sb-120 | — | 15.89 m | Electron capture / beta-plus decay (100%) | -88,417.13 keV | 8,475.63 keV | 4.79 × 10-19 eV |
| Sb-122 | — | 2.7238 d | Beta-minus decay (97.59%), Electron capture / beta-plus decay (2.41%) | -88,334.21 keV | 8,468.32 keV | 1.94 × 10-21 eV |
| Sb-124 | — | 60.20 d | Beta-minus decay (100%) | -87,619.07 keV | 8,456.15 keV | 8.77 × 10-23 eV |
| Sb-125 | — | 2.75856 Y | Beta-minus decay (100%) | -88,255.09 keV | 8,458.16 keV | 5.24 × 10-24 eV |
| Sb-126 | — | 12.35 d | Beta-minus decay (100%) | -86,393.14 keV | 8,440.31 keV | 4.28 × 10-22 eV |
| Sb-127 | — | 3.85 d | Beta-minus decay (100%) | -86,698.29 keV | 8,439.81 keV | 1.37 × 10-21 eV |
| Sb-128 | — | 9.05 h | Beta-minus decay (100%) | -84,629.85 keV | 8,420.77 keV | 1.40 × 10-20 eV |
| Sb-129 | — | 4.366 h | Beta-minus decay (100%) | -84,629.38 keV | 8,418.06 keV | 2.90 × 10-20 eV |
| Sb-130 | — | 39.5 m | Beta-minus decay (100%) | -82,285.69 keV | 8,397.36 keV | 1.93 × 10-19 eV |
| Sb-131 | — | 23.03 m | Beta-minus decay (100%) | -81,981.41 keV | 8,392.55 keV | 3.30 × 10-19 eV |
| Sb-132 | — | 2.79 m | Beta-minus decay (100%) | -79,635.28 keV | 8,372.35 keV | 2.73 × 10-18 eV |
| Sb-133 | — | 2.34 m | Beta-minus decay (100%) | -78,923.51 keV | 8,364.73 keV | 3.25 × 10-18 eV |
| Sb-134 | — | 0.78 s | Beta-minus decay (100%) | -74,019 keV | 8,325.94 keV | 5.85 × 10-16 eV |
| Sb-135 | — | 1.679 s | Beta-minus decay (100%), Beta-minus, neutron emission (22%) | -69,690.33 keV | 8,291.99 keV | 2.72 × 10-16 eV |
| Sb-136 | — | 0.923 s | Beta-minus decay (100%), Beta-minus, neutron emission (18.5%), B-2N (1%) | -64,506.89 keV | 8,252.25 keV | 4.94 × 10-16 eV |
| Sb-137 | — | 450 ms | Beta-minus decay (100%), Beta-minus, neutron emission (49%) | -60,060.39 keV | 8,218.48 keV | 1.01 × 10-15 eV |
| Sb-138 | — | 348 ms | Beta-minus, neutron emission (72%), Beta-minus decay, B-2N | -54,650 keV | 8,178 keV | 1.31 × 10-15 eV |
| Sb-139 | — | 93 ms | Beta-minus decay (100%), Beta-minus, neutron emission (90%), B-2N | -50,050 keV | 8,144 keV | 4.91 × 10-15 eV |
| Sb-140 | — | 173 ms | Beta-minus decay (100%), Beta-minus, neutron emission (23%), B-2N (7.6%) | -44,390 keV | 8,103 keV | 2.64 × 10-15 eV |
| Sb-141 | — | 103 ms | Beta-minus decay (100%), B-2N, Beta-minus, neutron emission | -39,540 keV | 8,069 keV | 4.43 × 10-15 eV |
| Sb-142 | — | 53 ms | Beta-minus decay (100%), B-2N, Beta-minus, neutron emission | -33,610 keV | 8,027 keV | 8.61 × 10-15 eV |