Neon
[He] 2s² 2p⁶ · 2 · 8
A noble gas whose one notable chemical property is having no chemistry at all. In an electric discharge, though, neon glows the orange-red that defined the look of the twentieth-century night city.
3D model
Bohr model: nucleus and electron shells from the real configuration. Valence electrons are highlighted.
Drag to rotate, scroll to zoom
Atomic properties
- Atomic number
- 10
- Atomic mass
- 20.18 а.е.м.
- Electron configuration
- [He] 2s² 2p⁶
- Electrons per shell
- 2 · 8
- Block
- p-block
- Group
- Noble gases
- Period
- 2
- Electronegativity (Pauling)
- no data
- Electronegativity (Allen)
- 4.79
- Atomic radius
- 38 pm
- Covalent radius
- 58 pm
- Van der Waals radius
- 154 pm
- Ionisation energy 1
- 2 080.7 kJ/mol
- Ionisation energy 2
- 3 952.3 kJ/mol
- Ionisation energy 3
- 6 122 kJ/mol
- Electron affinity
- 0 kJ/mol
- Common oxidation states
- 0
- Oxidation states
- 0
Physical properties
- State at 25 °C
- gas
- Density
- 0.0009 g/cm³
- Melting point
- 24.56 K · -248.6 °C
- Boiling point
- 27.1 K · -246 °C
- Speed of sound
- 936 m/s
Thermal properties
- Heat of fusion
- 0.335 kJ/mol
- Heat of vaporisation
- 1.71 kJ/mol
- Specific heat capacity
- 1.03 J/(g·K)
- Thermal conductivity
- 0.0491 W/(m·K)
Mechanical properties
- Young's modulus
- no data
- Shear modulus
- no data
- Bulk modulus
- no data
- Poisson ratio
- no data
- Mohs hardness
- no data
- Brinell hardness
- no data
Electrical and magnetic properties
- Electrical resistivity
- no data
- Magnetic ordering
- diamagnetic
- Curie point
- no data
- Néel point
- no data
- Superconducting point
- no data
Crystal structure
- Crystal structure
- face-centred cubic (fcc)
- Lattice constants
- a = 442.9 pm
Abundance
- In the crust
- 0.005 mg/kg
- In the ocean
- 0.00012 mg/L
- In the universe
- 1.3·10⁶ mg/kg
- In the human body
- 0 mg/kg
Isotopes
| Isotope | Abundance | Half-life | Decay mode |
|---|---|---|---|
| 20Ne | 90.48 % | stable | — |
| 21Ne | 0.27 % | stable | — |
| 22Ne | 9.25 % | stable | — |
Neon isotope ratios in meteorites and mantle rocks point to primordial gas trapped as the Earth formed.
Discovery
- Year of discovery
- 1898
- Discovered by
- William Ramsay and Morris Travers
- Where
- England
- Origin of the name
- from Greek neos (new)
History
Ramsay and Travers found neon in 1898 while distilling liquid air in search of the missing noble gases. On seeing the spectrum, Travers wrote that the crimson glow "told its own story".
Where it occurs
18 ppm of the atmosphere — rare on Earth, but the fifth most abundant element in the universe. Earth lost nearly all of its primordial neon.
How it is produced
Only from air, by fractional distillation. Its low concentration makes neon markedly dearer than argon or helium.
Role in living things
No biological role; it does not linger in the body or take part in any reaction.
Safety
Non-toxic and chemically harmless; the only hazard is oxygen displacement in a confined space.
Uses
- Discharge tubes: neon signage and indicator lamps
- A cryogenic refrigerant in the 25–40 K range, more effective per unit volume than liquid helium
- Excimer lasers for chip photolithography
- High-voltage spark gaps and lightning arresters
Curiosities
- Real neon glows only red-orange: signs in other colours hold argon or xenon, or are phosphor-coated.
- Liquid neon has forty times the refrigerating capacity per unit volume of liquid helium.
- Neon is so inert that not one stable compound of it is known — not even fluorine will touch it.
- The name came from Ramsay's thirteen-year-old son Willie, who suggested the Greek for new.