Antimony (Sb)
Antimony (symbol Sb) is the chemical element with atomic number 51: a metalloid, solid at 0 °C, with an atomic mass of 121.76 u. Known since antiquity.
Antimony is a brittle metalloid known since antiquity: its black sulfide was used as eye makeup. Today it is used mainly to make plastics and textiles less flammable and to harden the lead in batteries. China controls a large share of its production, making it a material seen as strategic.
Key facts
- Atomic number
- 51
- Symbol
- Sb
- French name
- Antimoine
- Atomic mass
- 121.76 u
- Molar mass
- 121.76 g/mol
- Family
- Metalloids
- Position
- period 5, group 15, p-block
- State at 0 °C
- Solid
- Melting point
- 630.6 °C
- Boiling point
- 1,634.9 °C
- Density
- 6.7 g/cm³
- Electronegativity (Pauling)
- 2.05
- First ionization energy
- 834 kJ/mol
- Atomic radius
- 145 pm
- Electron configuration
- [Kr] 4d¹⁰ 5s² 5p³
- Abundance in Earth's crust
- 0.2 ppm (65th most abundant element)
- Indicative price
- 6 $/kg (order of magnitude)
- Radioactive
- no
- Discovery
- Antiquity
Origin of the name
From the medieval Latin antimonium; the symbol Sb comes from stibium.
What does antimony look like?
A gray, silvery solid with bluish glints, metallic-looking and very brittle, that breaks into flaky crystals.
Where is antimony found?
About 0.2 ppm of Earth's crust. It is concentrated mostly in stibnite, a sulfide that forms spectacular needle-like crystals.
Natural sources
- Stibnite
- Valentinite
- Native antimony
- Tetrahedrite
How is antimony produced?
Stibnite is roasted into oxide and then reduced with carbon, or reduced directly with iron. World mine output is on the order of 80,000 to 100,000 tonnes a year, nearly half of it in China.
Top producers
- China
- Tajikistan
- Turkey
- Russia
- Bolivia
What is antimony used for?
- Flame retardants (antimony trioxide) in plastics and textiles.
- Hardening the lead in car batteries.
- Catalyst for making PET plastic.
- Fining (clarifying) display glass and technical glass.
- Ammunition and antifriction alloys.
In everyday life
- Lead-acid car battery
- PET plastic bottle
- Flame-retardant curtains and foams
Role in living things
No biological role. Antimony compounds are, however, used as drugs against leishmaniasis, a tropical parasitic disease.
Hazards of antimony
Its compounds are toxic, in ways similar to but milder than those of its neighbor arsenic: vomiting, heart and liver damage. Antimony trioxide is classified as a possible carcinogen.
Cosmic origin
- Neutron stars: Created when two neutron stars collide — the “forge” of gold.
- Dying stars: Made slowly in red giants (stars like the Sun at the end of their lives).
History of antimony
Egyptians used ground stibnite as kohl as early as the 3rd millennium BC (the makeup was also made from galena). The symbol Sb comes from the Latin stibium. Alchemists were fascinated by it, and 17th-century treatises describe how to prepare it in metallic form.
Did you know?
- Like water, antimony expands as it solidifies: added to the lead of printing type, it produced crisp letters that filled the whole mold.
- People once swallowed antimony “everlasting pills” as a purgative; recovered after use, they could be used again and were handed down in families.
- Stibnite crystals from the Wuning mine in China are prized pieces in mineralogy museums.
Isotopes of antimony
Two stable isotopes, antimony-121 and antimony-123. Antimony-124, paired with beryllium, makes a neutron source for starting up reactors.
- antimony-121: 57.21% of natural antimony, stable
- antimony-123: 42.79% of natural antimony, stable
- antimony-124: radioactive, half-life 60.2 days. Coupled with beryllium, it serves as a startup neutron source.
- antimony-125: radioactive, half-life 2.76 years. Fission product found in discharges from nuclear reprocessing.
Related elements
Same family (metalloids): Boron (B), Silicon (Si), Germanium (Ge), Arsenic (As), Tellurium (Te).
Same column (group 15): Nitrogen (N), Phosphorus (P), Arsenic (As), Bismuth (Bi), Moscovium (Mc).