He 2

Helium (He)

noble-gas

Period: 1 Group: 18 Block: s

Gas

Standard Atomic Weight

Electron configuration

1s²

Melting point

-272.2 °C (0.95 K)

Boiling point

-268.93 °C (4.22 K)

Density

0.1785 kg/m³

Oxidation states

Electronegativity (Pauling)

N/A

Ionization energy (1st)

Discovery year

1868

Atomic radius

120 pm

Details

Name origin Greek: hêlios (sun).

Discovery country Scotland/Sweden

Discoverers Sir William Ramsey, Nils Langet, P.T.Cleve

Helium is a noble gas and the second element in the periodic table. It is chemically inert under ordinary conditions because its 1s electron shell is filled, and it exists as monatomic He rather than as a molecule. Its low density, very low boiling point, high thermal conductivity, and nonflammability make it technologically important. On Earth it is uncommon in the atmosphere but can accumulate in some natural gas reservoirs through radioactive decay of uranium and thorium.

Helium has the lowest melting point of any element and is widely used in cryogenic research because its boiling point is close to absolute zero. Also, the element is vital in the study of super conductivity.

Using liquid helium, Kurti, co-workers and others have succeeded in obtaining temperatures of a few microkelvins by the adiabatic demagnetization of copper nuclei.

Helium has other peculiar properties: It is the only liquid that cannot be solidified by lowering the temperature. It remains liquid down to absolute zero at ordinary pressures, but will readily solidify by increasing the pressure. Solid 3He and 4He are unusual in that both can be changed in volume by more than 30% by applying pressure.

The specific heat of helium gas is unusually high. The density of helium vapor at the normal boiling point is also very high, with the vapor expanding greatly when heated to room temperature. Containers filled with helium gas at 5 to 10 K should be treated as though they contained liquid helium due to the large increase in pressure resulting from warming the gas to room temperature.

While helium normally has a 0 valence, it seems to have a weak tendency to combine with certain other elements. Means of preparing helium difluoride have been studied, and species such as HeNe and the molecular ions He+ and He++ have been investigated.

The name derives from the Greek helios for "sun". The element was discovered by spectroscopy during a solar eclipse in the sun's chromosphere by the French astronomer Pierre-Jules-Cesar Janssen in 1868. It was independently discovered and named helium by the English astronomer Joseph Norman Lockyer.

Helium was thought to be only a solar constituent until it was later found to be identical to the helium in the uranium ore cleveite by the Scottish chemist William Ramsay in 1895. The Swedish chemists Per Theodore Cleve and Nils Abraham Langet independently found helium in cleveite at about the same time.

Helium, the second most abundant element in the universe, was discovered on the sun before it was found on the earth. Pierre-Jules-César Janssen, a French astronomer, noticed a yellow line in the sun's spectrum while studying a total solar eclipse in 1868. Sir Norman Lockyer, an English astronomer, realized that this line, with a wavelength of 587.49 nanometers, could not be produced by any element known at the time. It was hypothesized that a new element on the sun was responsible for this mysterious yellow emission. This unknown element was named helium by Lockyer. The hunt to find helium on earth ended in 1895. Sir William Ramsay, a Scottish chemist, conducted an experiment with a mineral containing uranium called clevite. He exposed the clevite to mineral acids and collected the gases that were produced. He then sent a sample of these gases to two scientists, Lockyer and Sir William Crookes, who were able to identify the helium within it. Two Swedish chemists, Nils Langlet and Per Theodor Cleve, independently found helium in clevite at about the same time as Ramsay.

Helium makes up about 0.0005% of the earth's atmosphere. This trace amount of helium is not gravitationally bound to the earth and is constantly lost to space. The earth's atmospheric helium is replaced by the decay of radioactive elements in the earth's crust. Alpha decay, one type of radioactive decay, produces particles called alpha particles. An alpha particle can become a helium atom once it captures two electrons from its surroundings. This newly formed helium can eventually work its way to the atmosphere through cracks in the crust.

From the Greek word helios, the sun. Janssen obtained the first evidence of helium during the solar eclipse of 1868 when he detected a new line in the solar spectrum. Lockyer and Frankland suggested the name helium for the new element. In 1895 Ramsay discovered helium in the uranium mineral cleveite while it was independently discovered in cleveite by the Swedish chemists Cleve and Langlet at about the same time. Rutherford and Royds in 1907 demonstrated that alpha particles are helium nuclei.

Read about Helium on Wikipedia

Images

Properties

Physical

Atomic radius (empirical) 120 pm

Covalent radius 28 pm

Van der Waals radius 140 pm

Density

Molar volume 0.0318 L/mol

Phase at STP gas

Melting point -272.2 °C

Boiling point -268.93 °C

Thermal conductivity 0.152 W/(m·K)

Specific heat capacity 5.193 J/(g·K)

Molar heat capacity 20.786 J/(mol·K)

Crystal structure hcp

Chemical

Electronegativity (Allen) 4.16

Electron affinity

Ionization energy (1st)

Ionization energy (2nd)

Oxidation states 0

Valence electrons 2

Electron configuration

Electron configuration (semantic)

Thermodynamic

Triple point (temperature) -270.973 °C

Triple point (pressure) 5043 Pa

Critical point (temperature) -267.955 °C

Critical point (pressure) 2.274600e+5 Pa

Heat of fusion 1.430274e-4 eV

Heat of vaporization 8.291444e-4 eV

Heat of atomization 0 eV

Nuclear

Stable isotopes 2

Discovery year 1868

Abundance

Abundance (Earth's crust) 0.008 mg/kg

Abundance (ocean)

Reactivity

N/A

Crystal Structure

Lattice constant a 357 pm

Electronic Structure

Electrons per shell 2

Identifiers

CAS number 7440-59-7

Term symbol

InChI InChI=1S/He

InChI Key SWQJXJOGLNCZEY-UHFFFAOYSA-N

Electron Configuration Measured

Ion charge

Protons 2

Electrons 2

Charge Neutral

Configuration He: 1s²

1s²

Orbital diagram

↑↓

2/2

Total electrons: 2 Unpaired: 0

Atomic model

Protons 2

Neutrons 2

Electrons 2

Mass number 4

Stability Stable

Isotopes change neutron count, mass, and stability — not the electron configuration of a neutral atom.

Schematic atomic model, not to scale.

Atomic Fingerprint

Emission / Absorption Spectrum

Emission Visible: 380–750 nm

Isotope Distribution

Mass number	Atomic mass (u)	Natural abundance	Half-life
3 Stable	3.0160293201 ± 0.0000000025	0.0001%	Stable
4 Stable	4.00260325413 ± 0.00000000006	99.9999%	Stable

Measured

Phase / State

Gas 25 °C (298.15 K)

Reason: 293.9 °C above boiling point (-268.93 °C)

Melting point -272.2 °C

Boiling point -268.93 °C

Above boiling by 293.9 °C

0 K Current temperature: 25 °C 6000 K

Phase timeline

Schematic, not to scale

Solid

Liquid

Gas

Melting

Boiling

25°C

Solid

Liquid

Gas

Current

Phase transition points

Melting point Literature

-272.2 °C

Boiling point Literature

-268.93 °C

Current phase Calculated
Gas

Transition energies

Heat of fusion Literature

1.430274e-4 eV

Energy required to melt 1 mol at melting point

Heat of vaporization Literature

8.291444e-4 eV

Energy required to vaporize 1 mol at boiling point

Density

Reference density Literature

0.1785 kg/m³

At standard conditions

Current density Estimated

0.16360253 kg/m³

Estimated via ideal gas law at current T

Advanced

Triple point Literature

-270.973 °C

Critical point Literature

-267.955 °C

Atomic Spectra

Lines Holdings ?

Ion	Charge	Total lines	Transition probabilities	Level designations
3He I Isotope	0	2289	0	2289
He I	0	2300	2289	2300
He II	+1	140	140	140
3He II Isotope	+1	140	140	140

NIST Lines Holdings →

Levels Holdings ?

Ion	Charge	Levels
3He I Isotope	0	188
He I	0	843
He II	+1	149
3He II Isotope	+1	149

NIST Levels Holdings →

2 He 4.002602

Helium — Atomic Orbital Visualizer

1s2

Energy levels 2

Oxidation states 0

HOMO 1s n=1 · l=0 · m=0

Helium — Atomic Orbital Visualizer Preview

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2 He 4.002602

Helium — Crystal Structure Visualizer

Primitive Hexagonal · Pearson hP2

Experimental

Pearson hP2

Coord. № 12

Packing 74.048%

No crystal structure at standard conditions — gas at 298 K, 1 atm

Solid phase structure at 293 K

Helium — Crystal Structure Visualizer Preview

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Compounds

4.003 u

3.016 u

8.034 u

6.019 u

4.003 u

Isotopes (2)

Seven isotopes of helium are known: Liquid helium (He-4) exists in two forms: He-4I and He-4II, with a sharp transition point at 2.174K. He-4I (above this temperature) is a normal liquid, but He-4II (below it) is unlike any other known substance. It expands on cooling, its conductivity for heat is enormous, and neither its heat conduction nor viscosity obeys normal rules.

	Mass number	Atomic mass (u)	Natural abundance	Half-life	Decay mode
	3 Stable	3.0160293201 ± 0.0000000025	0.0001% ± 0.0000%	Stable	stable
	4 Stable	4.00260325413 ± 0.00000000006	99.9999% ± 0.0000%	Stable	stable

3 Stable

Atomic mass (u) 3.0160293201 ± 0.0000000025

Natural abundance 0.0001% ± 0.0000%

Half-life Stable

Decay mode

stable

4 Stable

Atomic mass (u) 4.00260325413 ± 0.00000000006

Natural abundance 99.9999% ± 0.0000%

Half-life Stable

Decay mode

stable

Spectral Lines

Wavelength (nm)	Intensity	Ion stage	Type	Transition	Accuracy	Source
381.9601975 nm	N/A	He I	emission	1s.2p 3P* → 1s.6d 3D	Measured	NIST
381.9602773 nm	N/A	He I	emission	1s.2p 3P* → 1s.6d 3D	Measured	NIST
381.9602828 nm	N/A	He I	emission	1s.2p 3P* → 1s.6d 3D	Measured	NIST
381.9613129 nm	N/A	He I	emission	1s.2p 3P* → 1s.6d 3D	Measured	NIST
381.9613927 nm	N/A	He I	emission	1s.2p 3P* → 1s.6d 3D	Measured	NIST
381.975731 nm	1	He I	emission	1s.2p 3P* → 1s.6d 3D	Measured	NIST
383.3548713 nm	0	He I	emission	1s.2p 1P* → 1s.10d 1D	Measured	NIST
383.8100125 nm	N/A	He I	emission	1s.2p 1P* → 1s.10s 1S	Measured	NIST
386.7472343 nm	N/A	He I	emission	1s.2p 3P* → 1s.6s 3S	Measured	NIST
386.7483778 nm	N/A	He I	emission	1s.2p 3P* → 1s.6s 3S	Measured	NIST
386.7631595 nm	1	He I	emission	1s.2p 3P* → 1s.6s 3S	Measured	NIST
387.1786406 nm	1	He I	emission	1s.2p 1P* → 1s.9d 1D	Measured	NIST
387.8176858 nm	N/A	He I	emission	1s.2p 1P* → 1s.9s 1S	Measured	NIST
388.8604644 nm	N/A	He I	emission	1s.2s 3S → 1s.3p 3P*	Measured	NIST
388.864559 nm	N/A	He I	emission	1s.2s 3S → 1s.3p 3P*	Measured	NIST
388.8648915 nm	N/A	He I	emission	1s.2s 3S → 1s.3p 3P*	Measured	NIST
392.6544387 nm	1	He I	emission	1s.2p 1P* → 1s.8d 1D	Measured	NIST
393.5945223 nm	0	He I	emission	1s.2p 1P* → 1s.8s 1S	Measured	NIST
396.4728829 nm	20	He I	emission	1s.2s 1S → 1s.4p 1P*	Measured	NIST
397.2015454 nm	N/A	He I	emission	1s.2s 1S → 1s.4d 1D	Measured	NIST
400.9256516 nm	1	He I	emission	1s.2p 1P* → 1s.7d 1D	Measured	NIST
402.3979795 nm	1	He I	emission	1s.2p 1P* → 1s.7s 1S	Measured	NIST
402.6184368 nm	N/A	He I	emission	1s.2p 3P* → 1s.5d 3D	Measured	NIST
402.6185901 nm	N/A	He I	emission	1s.2p 3P* → 1s.5d 3D	Measured	NIST
402.6186005 nm	N/A	He I	emission	1s.2p 3P* → 1s.5d 3D	Measured	NIST
402.619676 nm	N/A	He I	emission	1s.2p 3P* → 1s.5d 3D	Measured	NIST
402.6198294 nm	N/A	He I	emission	1s.2p 3P* → 1s.5d 3D	Measured	NIST
402.6356959 nm	5	He I	emission	1s.2p 3P* → 1s.5d 3D	Measured	NIST
412.0810765 nm	N/A	He I	emission	1s.2p 3P* → 1s.5s 3S	Measured	NIST
412.0823747 nm	N/A	He I	emission	1s.2p 3P* → 1s.5s 3S	Measured	NIST
412.0991564 nm	2	He I	emission	1s.2p 3P* → 1s.5s 3S	Measured	NIST
414.1332157 nm	N/A	He I	emission	1s.2p 1P* → 1s.6p 1P*	Measured	NIST
414.3759059 nm	3	He I	emission	1s.2p 1P* → 1s.6d 1D	Measured	NIST
416.8971512 nm	1	He I	emission	1s.2p 1P* → 1s.6s 1S	Measured	NIST
438.3278555 nm	N/A	He I	emission	1s.2p 1P* → 1s.5p 1P*	Measured	NIST
438.7929143 nm	10	He I	emission	1s.2p 1P* → 1s.5d 1D	Measured	NIST
443.7553428 nm	3	He I	emission	1s.2p 1P* → 1s.5s 1S	Measured	NIST
447.1470373 nm	N/A	He I	emission	1s.2p 3P* → 1s.4d 3D	Measured	NIST
447.1474077 nm	N/A	He I	emission	1s.2p 3P* → 1s.4d 3D	Measured	NIST
447.1474317 nm	N/A	He I	emission	1s.2p 3P* → 1s.4d 3D	Measured	NIST
447.1485658 nm	N/A	He I	emission	1s.2p 3P* → 1s.4d 3D	Measured	NIST
447.1489362 nm	N/A	He I	emission	1s.2p 3P* → 1s.4d 3D	Measured	NIST
447.1683251 nm	25	He I	emission	1s.2p 3P* → 1s.4d 3D	Measured	NIST
468.537685 nm	N/A	He II	emission	3p 2P* → 4d 2D	Measured	NIST
468.5407226 nm	N/A	He II	emission	3s 2S → 4p 2P*	Measured	NIST
468.5524404 nm	N/A	He II	emission	3p 2P* → 4s 2S	Measured	NIST
468.5568006 nm	N/A	He II	emission	3s 2S → 4p 2P*	Measured	NIST
468.570385 nm	N/A	He II	emission	3d 2D → 4f 2F*	Measured	NIST
468.570438 nm	N/A	He II	emission	3p 2P* → 4d 2D	Measured	NIST
468.575708 nm	N/A	He II	emission	3d 2D → 4p 2P*	Measured	NIST
468.5757975 nm	N/A	He II	emission	3p 2P* → 4d 2D	Measured	NIST
468.5804092 nm	N/A	He II	emission	3d 2D → 4f 2F*	Measured	NIST
468.583089 nm	N/A	He II	emission	3d 2D → 4f 2F*	Measured	NIST
468.5884123 nm	N/A	He II	emission	3d 2D → 4p 2P*	Measured	NIST
468.5905553 nm	N/A	He II	emission	3p 2P* → 4s 2S	Measured	NIST
468.5917885 nm	N/A	He II	emission	3d 2D → 4p 2P*	Measured	NIST
471.3139173 nm	N/A	He I	emission	1s.2p 3P* → 1s.4s 3S	Measured	NIST
471.3156155 nm	N/A	He I	emission	1s.2p 3P* → 1s.4s 3S	Measured	NIST
471.3375684 nm	4	He I	emission	1s.2p 3P* → 1s.4s 3S	Measured	NIST
491.074748 nm	N/A	He I	emission	1s.2p 1P* → 1s.4p 1P*	Measured	NIST
492.0612726 nm	N/A	He I	emission	1s.2p 1P* → 1s.4f 1F*	Measured	NIST
492.1931036 nm	20	He I	emission	1s.2p 1P* → 1s.4d 1D	Measured	NIST
501.567801 nm	100	He I	emission	1s.2s 1S → 1s.3p 1P*	Measured	NIST
504.208749 nm	N/A	He I	emission	1s.2s 1S → 1s.3d 1D	Measured	NIST
504.773857 nm	10	He I	emission	1s.2p 1P* → 1s.4s 1S	Measured	NIST
587.443388 nm	N/A	He I	emission	1s.2p 3P* → 1s.3d 1D	Measured	NIST
587.446026 nm	N/A	He I	emission	1s.2p 3P* → 1s.3d 1D	Measured	NIST
587.559871 nm	N/A	He I	emission	1s.2p 3P* → 1s.3d 3D	Measured	NIST
587.561397 nm	N/A	He I	emission	1s.2p 3P* → 1s.3d 3D	Measured	NIST
587.561484 nm	N/A	He I	emission	1s.2p 3P* → 1s.3d 3D	Measured	NIST
587.56251 nm	N/A	He I	emission	1s.2p 3P* → 1s.3d 3D	Measured	NIST
587.564036 nm	N/A	He I	emission	1s.2p 3P* → 1s.3d 3D	Measured	NIST
587.596628 nm	100	He I	emission	1s.2p 3P* → 1s.3d 3D	Measured	NIST
655.976872 nm	N/A	He II	emission	4p 2P* → 6d 2D	Measured	NIST
655.979395 nm	N/A	He II	emission	4s 2S → 6p 2P*	Measured	NIST
655.98544 nm	N/A	He II	emission	4p 2P* → 6s 2S	Measured	NIST
655.988733 nm	N/A	He II	emission	4s 2S → 6p 2P*	Measured	NIST
656.005227 nm	N/A	He II	emission	4d 2D → 6f 2F*	Measured	NIST
656.005274 nm	N/A	He II	emission	4p 2P* → 6d 2D	Measured	NIST
656.008318 nm	N/A	He II	emission	4d 2D → 6p 2P*	Measured	NIST
656.008387 nm	N/A	He II	emission	4p 2P* → 6d 2D	Measured	NIST
656.01416 nm	N/A	He II	emission	4f 2F* → 6g 2G	Measured	NIST
656.014176 nm	N/A	He II	emission	4d 2D → 6f 2F*	Measured	NIST
656.015708 nm	N/A	He II	emission	4f 2F* → 6d 2D	Measured	NIST
656.015732 nm	N/A	He II	emission	4d 2D → 6f 2F*	Measured	NIST
656.016955 nm	N/A	He II	emission	4p 2P* → 6s 2S	Measured	NIST
656.017657 nm	N/A	He II	emission	4d 2D → 6p 2P*	Measured	NIST
656.018478 nm	N/A	He II	emission	4f 2F* → 6g 2G	Measured	NIST
656.01882 nm	N/A	He II	emission	4f 2F* → 6d 2D	Measured	NIST
656.018823 nm	N/A	He II	emission	4d 2D → 6p 2P*	Measured	NIST
656.019412 nm	N/A	He II	emission	4f 2F* → 6g 2G	Measured	NIST
656.02096 nm	N/A	He II	emission	4f 2F* → 6d 2D	Measured	NIST
663.190187 nm	N/A	He I	emission	1s.2p 1P* → 1s.3p 1P*	Measured	NIST
667.815174 nm	100	He I	emission	1s.2p 1P* → 1s.3d 1D	Measured	NIST
667.967687 nm	N/A	He I	emission	1s.2p 1P* → 1s.3d 3D	Measured	NIST
706.517716 nm	N/A	He I	emission	1s.2p 3P* → 1s.3s 3S	Measured	NIST
706.521532 nm	N/A	He I	emission	1s.2p 3P* → 1s.3s 3S	Measured	NIST
706.570863 nm	30	He I	emission	1s.2p 3P* → 1s.3s 3S	Measured	NIST
716.055563 nm	N/A	He I	emission	1s.3s 3S → 1s.10p 3P*	Measured	NIST
716.055907 nm	N/A	He I	emission	1s.3s 3S → 1s.10p 3P*	Measured	NIST
716.055935 nm	N/A	He I	emission	1s.3s 3S → 1s.10p 3P*	Measured	NIST
728.13508 nm	50	He I	emission	1s.2p 1P* → 1s.3s 1S	Measured	NIST
729.803204 nm	N/A	He I	emission	1s.3s 3S → 1s.9p 3P*	Measured	NIST
729.803696 nm	N/A	He I	emission	1s.3s 3S → 1s.9p 3P*	Measured	NIST
729.803736 nm	N/A	He I	emission	1s.3s 3S → 1s.9p 3P*	Measured	NIST
749.984714 nm	N/A	He I	emission	1s.3s 3S → 1s.8p 3P*	Measured	NIST
749.985457 nm	N/A	He I	emission	1s.3s 3S → 1s.8p 3P*	Measured	NIST
749.985518 nm	N/A	He I	emission	1s.3s 3S → 1s.8p 3P*	Measured	NIST

Extended Properties

Covalent Radii (Extended)

Covalent radius (Pyykkö)

Van der Waals Radii

Bondi

Alvarez

UFF

MM3

Atomic & Metallic Radii

Atomic radius (Rahm)

Metallic radius (C12)

Numbering Scales

Mendeleev

Pettifor

Glawe

Electronegativity Scales

Ghosh

Gunnarsson–Lundqvist

Robles–Bartolotti

Polarizability & Dispersion

Dipole polarizability

Dipole polarizability (unc.)

C₆

C₆ (Gould–Bučko)

Chemical Affinity

Proton affinity

Gas basicity

Supply Risk & Economics

Production concentration

Relative supply risk

Reserve distribution

Political stability (top producer)

Political stability (top reserve)

Noble Gas Properties

Density (25 °C) 0.164 g/L

Reactions

Phase Transitions & Allotropes

Boiling point	4.22 K
Critical point (temperature)	5.19 K
Critical point (pressure)	0.23 MPa
Triple point (temperature)	2.18 K
Triple point (pressure)	5.04 kPa

Advanced Reference Data

Screening Constants (1)

n	Orbital	σ
1	s	0.3125

Isotope Decay Modes (9)

Isotope	Mode	Intensity
5	n	100%
6	B-	100%
6	B-d	0%
7	n	100%
8	B-	100%
8	B-n	16%
8	B-t	0.9%
9	n	100%
10	2n	100%

X‑ray Scattering Factors (501)

Energy (eV)	f₁	f₂
10	—	0
10.1617	—	0
10.3261	—	0
10.4931	—	0
10.6628	—	0
10.8353	—	0
11.0106	—	0
11.1886	—	0
11.3696	—	0
11.5535	—	0

Additional Data

Estimated Crustal Abundance

The estimated element abundance in the earth's crust.

8×10-3 milligrams per kilogram

References (1)

[5] Helium https://education.jlab.org/itselemental/ele002.html

Estimated Oceanic Abundance

The estimated element abundance in the earth's oceans.

7×10-6 milligrams per liter

References (1)

[5] Helium https://education.jlab.org/itselemental/ele002.html

Sources

Sources of this element.

Except for hydrogen, helium is the most abundant element found in the universe. Helium is extracted from natural gas. In fact, all natural gas contains at least trace quantities of helium.

It has been detected spectroscopically in great abundance, especially in the hotter stars, and it is an important component in both the proton-proton reaction and the carbon cycle, which account for the energy of the sun and stars.

The helium content of the atmosphere is about 1 part in 200,000. While it is present in various radioactive minerals as a decay product, the bulk of the Free World's supply is obtained from wells in Texas, Oklahoma, and Kansas. Outside the United States, the only known helium extraction plants, in 1984 were in Eastern Europe (Poland), the USSR, and a few in India.

References (1)

[6] Helium https://periodic.lanl.gov/2.shtml

References

(9)

1 PubChem

Data deposited in or computed by PubChem

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2 Atomic Mass Data Center (AMDC), International Atomic Energy Agency (IAEA)

The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.

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3 IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW)

Helium

Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.

Visit source License

4 IUPAC Periodic Table of the Elements and Isotopes (IPTEI)

The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.

Visit source License

License note: Copyright (c) 2020 International Union of Pure and Applied Chemistry. The International Union of Pure and Applied Chemistry (IUPAC) contribution within Pubchem is provided under a CC-BY-NC-ND 4.0 license, unless otherwise stated.

5 Jefferson Lab, U.S. Department of Energy

Helium

Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/

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License note: Please see citation and linking information: https://education.jlab.org/faq/index.html

6 Los Alamos National Laboratory, U.S. Department of Energy

Helium

The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.

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7 NIST Physical Measurement Laboratory

Helium

The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database

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8 PubChem Elements

Helium

This section provides all form of data related to element Helium.

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9 PubChem Elements

Helium

The element property data was retrieved from publications.

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Last updated: May 1, 2026

Data verified: May 12, 2026

Content is reviewed against latest scientific data.