Neon

Neon (Ne) is a noble gas with atomic number 10 and an atomic mass of 20.18. Its electron configuration is [He] 2s2 2p6, which gives it 8 valence electrons.

Neon key data

Symbol	Ne
Atomic number	10
Atomic mass (standard atomic weight)	20.18
Molar mass	20.18 g/mol
Protons	10
Neutrons (most abundant isotope, neon-20)	10
Electrons (neutral atom)	10
Valence electrons	8
Category	Noble gas
Period	2
Group	18
Block	p-block
Noble gas notation	[He] 2s2 2p6
Full electron configuration	1s2 2s2 2p6
Electrons per shell	2, 8

Atomic mass: IUPAC CIAAW abridged standard atomic weights, 2024. Most abundant isotope: NIST Atomic Weights and Isotopic Compositions.

Measured properties of neon

From PubChem, the US National Institutes of Health. Public domain. PubChem’s periodic table gives no value for the rows not shown.

Melting point	24.56 K (−248.59 °C), 101st of 103 by melting point
Boiling point	27.07 K (−246.08 °C), 91st of 93 by boiling point
Density	0.0008999 g/cm³, 94th of 96 by density
State at room temperature	Gas
Van der Waals radius	154 pm, 92nd of 99 by atomic radius
First ionisation energy	21.565 eV (2080.7 kJ/mol), 2nd of 102 by first ionisation energy
Common oxidation states	0
Discovered	1898

Each rank counts down from the highest value, among the elements PubChem’s table gives one for, and links to that property ranked across the whole table. All of them are collected under periodic trends.

Neon electron configuration

The full electron configuration of neon is 1s2 2s2 2p6. With the noble-gas core collapsed it is [He] 2s2 2p6, and the outermost subshell is 2p6.

Bohr model of neon (Ne): a nucleus and two shells holding 2 and 8 electrons from the inside out. — Bohr model of neon (Ne). Image © ScienceQuest, CC BY 4.0: free to reuse with credit to ScienceQuest and a link to this page, as the image licence explains.

Orbital box diagram of neon (Ne), 1s2 2s2 2p6: one box per orbital, filled by Hund’s rule, showing every orbital drawn holds a pair of electrons. — Orbital diagram of neon (Ne). Image © ScienceQuest, CC BY 4.0: free to reuse with credit to ScienceQuest and a link to this page, as the image licence explains.

Why group and block follow from this is set out in how the periodic table maps electron configuration, and the electron configuration of every element is listed on one page.

Mass of one neon atom

A molar mass is grams per mole, so dividing by the Avogadro constant gives the mass of a single atom, or for an element with more than one natural isotope the average mass of its atoms, and the reciprocal gives how many atoms sit in a gram.

Mass of one atom

one atom = 20.18 / (6.02214076 × 10²³)
= 3.3510 × 10⁻²³ g

Atoms in one gram

atoms per gram = 6.02214076 × 10²³ / 20.18
= 2.9842 × 10²² atoms

Neon on the periodic table

Neon is in period 2, group 18, in the p-block.

The other elements of group 18 are helium, argon, krypton, xenon, radon and oganesson.