Neon Element Properties

Complete reference for Neon (Ne, element 10): atomic data, electron configuration, isotopes, physical constants, and thermodynamic properties.

10 Ne 20.180

Neon

Noble Gas — Period 2, Group 18

Atomic Identity

Atomic Number
10
Z
Symbol
Ne
Standard Atomic Wt.
20.1797 u
IUPAC 2021
Period
2
Group
18
VIIIA
Block
p-block
CAS Number
7440-01-9
Ne
Discovery
William Ramsay & Morris Travers
1898
Named After
Greek: neos
"new"

Electron Configuration

Full notation 1s² 2s² 2p⁶
Noble gas shorthand [Ne] (defines the neon core)
Electrons per shell 2, 8
Valence electrons 8
Unpaired electrons 0
Spin multiplicity 1 (singlet)
Orbital Diagram
1s
2s
2p
Diamagnetic

All orbitals fully paired

Isotopes of Neon

Isotope Symbol Protons Neutrons Mass (u) Natural Abundance Stability
Neon-20 ²⁰Ne 10 10 19.9924401754 90.48% Stable
Neon-21 ²¹Ne 10 11 20.9938853 0.27% Stable
Neon-22 ²²Ne 10 12 21.9913851 9.25% Stable
Neon-17 ¹⁷Ne 10 7 17.01767 Trace Unstable
β⁺ decay, t½ = 109.2 ms
Neon-19 ¹⁹Ne 10 9 19.0018802 Trace Unstable
β⁺ decay, t½ = 17.22 s
Neon-23 ²³Ne 10 13 22.9944669 Trace Unstable
β⁻ decay, t½ = 37.15 s
Neon-24 ²⁴Ne 10 14 23.9936108 Trace Unstable
β⁻ decay, t½ = 3.38 min

Physical Properties

State at STP Gas
Color Colorless
Odor Odorless
Density (gas, 0 °C, 1 atm) 0.9002 g/L
Density (liquid at bp) 1.207 g/cm³
Melting Point −248.59 °C (24.56 K) at 43.2 kPa
Boiling Point −246.08 °C (27.07 K)
Triple Point 24.556 K, 43.37 kPa
Critical Temperature −228.7 °C (44.49 K)
Critical Pressure 2.76 MPa
Heat of Vaporization 1.7326 kJ/mol
Heat of Fusion 0.335 kJ/mol
Specific Heat (gas) 20.786 J/(mol·K)
Thermal Conductivity 0.04991 W/(m·K) at 300 K
Speed of Sound (gas) 435 m/s (0 °C)
Viscosity 31.11 μPa·s (25 °C)

Chemical Properties

Electronegativity (Pauling) N/A (noble gas)
Electron Affinity −0.07 eV (essentially 0)
1st Ionization Energy 2080.7 kJ/mol (21.564 eV)
2nd Ionization Energy 3952.3 kJ/mol
3rd Ionization Energy 6122 kJ/mol
Covalent Radius 58 pm
Van der Waals Radius 154 pm
Oxidation States 0 (standard)
Reactivity Chemically inert
Magnetic Ordering Diamagnetic
Molar Volume (STP) 22.405 L/mol
Known Compounds None stable (std. conditions)
Flammability Non-flammable

Ground State Quantum Numbers

Principal (n) 2 (outermost shell)
Azimuthal (l) 1 (p orbital)
Magnetic (mₗ) −1, 0, +1 (all filled)
Spin (mₛ) All ±½ pairs
Term symbol ¹S₀
Degeneracy 1 (singlet ground state)

Notable Emission Lines

540.06 nm
Green
585.25 nm
Yellow-orange
614.31 nm
Orange
632.82 nm
Orange-red
640.22 nm
Red
703.24 nm
Deep red
724.52 nm
Far red

The combination of orange and red lines produces the iconic warm red-orange glow seen in neon signs and discharge tubes.

Key Facts About Neon

Neon Signs

Neon gas in sealed glass tubes was used in signs as early as 1910 by Georges Claude. The characteristic red-orange glow comes from electron transitions producing photons in the 580–750 nm range.

Second-Lowest Boiling Point

Neon boils at 27.07 K (−246.08 °C), giving liquid neon the second-lowest boiling point among all elements. It serves as an effective cryogenic coolant in the 27–40 K range, bridging the gap between liquid hydrogen and helium.

Highest Ionization Energy (Period 2)

Neon's first ionization energy of 21.56 eV is the second highest of all elements (after helium), making it the most resistant Period 2 element to ionization and virtually impossible to ionize under normal laboratory conditions.

He-Ne Laser

The helium-neon laser (632.8 nm red beam) is one of the oldest and most widely used laser types, relying on energy transfer from excited helium atoms to neon atoms, which then emit coherent red light.

Fifth Most Abundant in Universe

Neon is the fifth most abundant element in the universe by mass (after hydrogen, helium, oxygen, and carbon), produced primarily by alpha-capture reactions during stellar helium burning.

Cosmochemical Tracer

The ratio of neon isotopes (²¹Ne/²²Ne and ²⁰Ne/²²Ne) is used in cosmochemistry to trace solar wind exposure in meteorites, lunar samples, and the origin of noble gases trapped in Earth's mantle.

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Summary

Complete reference for Neon (Ne, element 10): atomic data, electron configuration, isotopes, physical constants, and thermodynamic properties.

How it works

  1. Browse the atomic identity section for symbol, atomic number, and standard atomic weight.
  2. Check the electron configuration panel for orbital notation and quantum numbers.
  3. Review the isotopes table for neon-20, neon-21, and neon-22 data including natural abundances.
  4. Consult the physical properties panel for boiling point, density, and state at STP.
  5. Use the chemical properties section to understand the noble gas behavior and ionization energies.
  6. Explore the spectral lines section to see the emission wavelengths responsible for the red-orange glow.
  7. Copy any value with one click for use in reports or calculations.

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Last updated: 2026-05-28 · Reviewed by Nham Vu