Antimony
[Kr] 4d¹⁰ 5s² 5p³ · 2 · 8 · 18 · 18 · 5
A metalloid known since antiquity as cosmetic and as medicine. Antimony expands on freezing — a rare property that made its alloy fill a type mould cleanly for Gutenberg's printing.
3D model
Bohr model: nucleus and electron shells from the real configuration. Valence electrons are highlighted.
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Atomic properties
- Atomic number
- 51
- Atomic mass
- 121.76 а.е.м.
- Electron configuration
- [Kr] 4d¹⁰ 5s² 5p³
- Electrons per shell
- 2 · 8 · 18 · 18 · 5
- Block
- p-block
- Group
- Pnictogens
- Period
- 5
- Electronegativity (Pauling)
- 2.05
- Electronegativity (Allen)
- 1.98
- Atomic radius
- 133 pm
- Covalent radius
- 139 pm
- Van der Waals radius
- 206 pm
- Ionisation energy 1
- 834 kJ/mol
- Ionisation energy 2
- 1 594.9 kJ/mol
- Ionisation energy 3
- 2 440 kJ/mol
- Ionisation energy 4
- 4 260 kJ/mol
- Ionisation energy 5
- 5 400 kJ/mol
- Electron affinity
- 101 kJ/mol
- Common oxidation states
- -3, +3, +5
- Oxidation states
- -3, -2, -1, +1, +2, +3, +4, +5
Physical properties
- State at 25 °C
- solid
- Density
- 6.697 g/cm³
- Melting point
- 903.78 K · 630.6 °C
- Boiling point
- 1 908 K · 1 634.9 °C
- Speed of sound
- 3 420 m/s
Thermal properties
- Heat of fusion
- 19.79 kJ/mol
- Heat of vaporisation
- 193.43 kJ/mol
- Specific heat capacity
- 0.207 J/(g·K)
- Thermal conductivity
- 24.4 W/(m·K)
Mechanical properties
- Young's modulus
- 55 GPa
- Shear modulus
- 20 GPa
- Bulk modulus
- 42 GPa
- Poisson ratio
- 0.25
- Mohs hardness
- 3
- Brinell hardness
- 294 MPa
Electrical and magnetic properties
- Electrical resistivity
- 417 nΩ·m
- Magnetic ordering
- diamagnetic
- Curie point
- no data
- Néel point
- no data
- Superconducting point
- no data
Crystal structure
- Crystal structure
- rhombohedral
- Lattice constants
- a = 430.7 pm · c = 1 127.3 pm
Abundance
- In the crust
- 0.2 mg/kg
- In the ocean
- 0.00024 mg/L
- In the universe
- 0.004 mg/kg
- In the human body
- 7·10⁻⁵ mg/kg
Isotopes
| Isotope | Abundance | Half-life | Decay mode |
|---|---|---|---|
| 121Sb | 57.21 % | stable | — |
| 123Sb | 42.79 % | stable | — |
Two stable isotopes. Antimony-125, half-life 2.8 years, is a fission product that matters in waste handling.
Discovery
- Year of discovery
- known since antiquity
- Discovered by
- known since antiquity
- Where
- no data
- Origin of the name
- the symbol Sb is from Latin stibium, the eye-paint mineral
History
Stibnite was used in Egypt as eye paint three thousand years BCE. The symbol Sb comes from Latin stibium, the name of exactly that cosmetic. Various antimony preparations served medieval medicine as emetics.
Where it occurs
0.2 mg/kg of the crust. The main mineral is stibnite, Sb₂S₃; over half of world production is in China.
How it is produced
By roasting stibnite to the oxide and reducing with carbon. A noticeable share comes alongside lead ores.
Role in living things
No biological role. Antimony compounds act much like arsenic ones, but more weakly.
Safety
Toxic, attacking the heart and liver. Pentavalent antimony drugs remain the mainstay treatment for leishmaniasis despite severe side effects.
Uses
- Antimony trioxide flame retardants in plastics and textiles — the largest use
- Lead-antimony alloys for battery grids
- Semiconductors: indium antimonide in infrared detectors
- A catalyst in PET plastic production
Curiosities
- Antimony expands on freezing, as water does — which is why type metal fills a letter mould exactly.
- Egyptian kohl eyeliner is antimony sulfide.
- Medieval Europe sold everlasting pills of metallic antimony: they acted as an emetic and, having passed through, were used again.
- The symbol Sb has nothing to do with the English name and comes from Latin stibium.