> **PROTOTYPE:** a suggestion, not an official CIAAW or IUPAC page. Official values are at [ciaaw.org](https://ciaaw.org).

# helium

| Property | Value |
| --- | --- |
| Symbol | He |
| Atomic number | 2 |
| IRI | `https://hendrikborgelt.github.io/Draft_for_IUPAC_CIAAW-Isotopic-Abundances-and-Atomic-Weights/elements/Helium` |
| Wikidata | [Q560](https://www.wikidata.org/wiki/Q560) |

## Standard atomic weight

| Value | Year | Source | Status | Declaration |
| --- | --- | --- | --- | --- |
| 4.002 602(2) | 1983 | [10.1351/pac198456060653](https://doi.org/10.1351/pac198456060653) | Current | [`AW-He-standard`](../id/AW-He-standard.md) |
| 4.002 60(1) | 1969 | [10.1351/pac197021010091](https://doi.org/10.1351/pac197021010091) | Deprecated, see [`AW-He-standard`](../id/AW-He-standard.md) | [`AW-He-standard-1969`](../id/AW-He-standard-1969.md) |
| 4.0026 | 1961 | [10.1021/ja00881a001](https://doi.org/10.1021/ja00881a001) | Deprecated, see [`AW-He-standard-1969`](../id/AW-He-standard-1969.md) | [`AW-He-standard-1961`](../id/AW-He-standard-1961.md) |
| 4.003 | 1938 | [10.1039/JR9380001101](https://doi.org/10.1039/JR9380001101) | Deprecated, see [`AW-He-standard-1961`](../id/AW-He-standard-1961.md) | [`AW-He-standard-1938`](../id/AW-He-standard-1938.md) |
| 4.002 | 1931 | [10.1039/JR9310001617](https://doi.org/10.1039/JR9310001617) | Deprecated, see [`AW-He-standard-1938`](../id/AW-He-standard-1938.md) | [`AW-He-standard-1931`](../id/AW-He-standard-1931.md) |
| 4 | 1916 | [10.1021/ja02176a001](https://doi.org/10.1021/ja02176a001) | Deprecated, see [`AW-He-standard-1931`](../id/AW-He-standard-1931.md) | [`AW-He-standard-1916`](../id/AW-He-standard-1916.md) |
| 3.99 | 1911 | [10.1021/ja01928a001](https://doi.org/10.1021/ja01928a001) | Deprecated, see [`AW-He-standard-1916`](../id/AW-He-standard-1916.md) | [`AW-He-standard-1911`](../id/AW-He-standard-1911.md) |
| 4 | 1902 | [10.1007/BF01370337](https://doi.org/10.1007/BF01370337) | Deprecated, see [`AW-He-standard-1911`](../id/AW-He-standard-1911.md) | [`AW-He-standard-1902`](../id/AW-He-standard-1902.md) |

Notes: [g](#note-g) [r](#note-r)

## Isotopes

| A | Representative isotopic composition | Year | Source | Declaration | ChEBI | Wikidata |
| --- | --- | --- | --- | --- | --- | --- |
| [3](../id/He-3.md) | 0.000 002(2) | — | — | [`Abundance-He3`](../id/Abundance-He3.md) | — | [Q533498](https://www.wikidata.org/wiki/Q533498) |
| [4](../id/He-4.md) | 0.999 998(2) | — | — | [`Abundance-He4`](../id/Abundance-He4.md) | — | [Q1151346](https://www.wikidata.org/wiki/Q1151346) |

Notes: [g](#note-g) [r](#note-r)

## Notes

<a id="note-g"></a>**g** Geological and biological materials are known in which the element has an isotopic composition outside the limits for normal material. The difference between the atomic weight of the element in such materials and that given in the table may exceed the stated uncertainty.

<a id="note-r"></a>**r** Range in isotopic composition of normal terrestrial material prevents a more precise standard atomic weight being given; the tabulated value and uncertainty should be applicable to normal material.

## Bibliography

<div class="csl-bib-body">
<div class="csl-entry">ANNUAL REPORT OF THE INTERNATIONAL COMMITTEE ON ATOMIC WEIGHTS, 1916. (1915). <i>Journal of the American Chemical Society</i>, <i>37</i>(11), 2449–2452. https://doi.org/10.1021/ja02176a001 <a href="https://doi.org/10.1021/ja02176a001">CrossRef</a> <a href="https://qlever.scholia.wiki/doi/10.1021/ja02176a001">Scholia</a></div>
<div class="csl-entry">Atomic weights of the elements 1969. (1970). <i>Pure and Applied Chemistry</i>, <i>21</i>(1), 91–108. https://doi.org/10.1351/pac197021010091 <a href="https://doi.org/10.1351/pac197021010091">CrossRef</a> <a href="https://qlever.scholia.wiki/doi/10.1351/pac197021010091">Scholia</a></div>
<div class="csl-entry">Baxter, G. P., Curie, Mme. M., Hönigschmid, O., Lebeau, P., &#38; Meyer, R. J. (1931). First Report of the Committee on the Atomic Weights of the International Union of Chemistry. <i>J. Chem. Soc.</i>, <i>0</i>(0), 1617–1627. https://doi.org/10.1039/jr9310001617 <a href="https://doi.org/10.1039/JR9310001617">CrossRef</a> <a href="https://qlever.scholia.wiki/doi/10.1039/JR9310001617">Scholia</a></div>
<div class="csl-entry">Baxter, G. P., Hönigschmid, O., &#38; Lebeau, P. (1938). Eighth Report of the Committee on Atomic Weights of the International Union of Chemistry. <i>J. Chem. Soc.</i>, <i>0</i>(0), 1101–1109. https://doi.org/10.1039/jr9380001101 <a href="https://doi.org/10.1039/JR9380001101">CrossRef</a> <a href="https://qlever.scholia.wiki/doi/10.1039/JR9380001101">Scholia</a></div>
<div class="csl-entry">Cameron, A. E., &#38; Wichers, Edward. (1962). <b>Report of the International Commission on Atomic Weights<sup>*</sup>(1961)</b>. <i>Journal of the American Chemical Society</i>, <i>84</i>(22), 4175–4197. https://doi.org/10.1021/ja00881a001 <a href="https://doi.org/10.1021/ja00881a001">CrossRef</a> <a href="https://qlever.scholia.wiki/doi/10.1021/ja00881a001">Scholia</a></div>
<div class="csl-entry">Clarke, F. W., Thorpe, T. E., Ostwald, W., &#38; Urbain, G. (1910). ANNUAL REPORT OF THE INTERNATIONAL COMMITTEE ON ATOMIC WEIGHTS, 1911. <i>Journal of the American Chemical Society</i>, <i>32</i>(10), 1113–1116. https://doi.org/10.1021/ja01928a001 <a href="https://doi.org/10.1021/ja01928a001">CrossRef</a> <a href="https://qlever.scholia.wiki/doi/10.1021/ja01928a001">Scholia</a></div>
<div class="csl-entry">Holden, N. E., &#38; Martin, R. L. (1984). Atomic weights of the elements 1983. <i>Pure and Applied Chemistry</i>, <i>56</i>(6), 653–674. https://doi.org/10.1351/pac198456060653 <a href="https://doi.org/10.1351/pac198456060653">CrossRef</a> <a href="https://qlever.scholia.wiki/doi/10.1351/pac198456060653">Scholia</a></div>
<div class="csl-entry">Richards, Baxter, Hinrichsen, Köthner, P., &#38; Pellini, S. (1902). Zur Festsetzung der Atomgewichte. <i>Fresenius’ Zeitschrift für analytische Chemie</i>, <i>41</i>(2), 139–140. https://doi.org/10.1007/bf01370337 <a href="https://doi.org/10.1007/BF01370337">CrossRef</a> <a href="https://qlever.scholia.wiki/doi/10.1007/BF01370337">Scholia</a></div>
</div>

## Turtle

This resource as a file: [Helium.ttl](Helium.ttl)

```turtle
# Prototype: a suggestion, not an official CIAAW or IUPAC record. Official values are at https://ciaaw.org

@prefix adms: <http://www.w3.org/ns/adms#> .
@prefix chemrof: <https://w3id.org/chemrof/> .
@prefix ciaaw: <https://hendrikborgelt.github.io/Draft_for_IUPAC_CIAAW-Isotopic-Abundances-and-Atomic-Weights/ciaaw-draft#> .
@prefix ciaaw_draft: <https://hendrikborgelt.github.io/Draft_for_IUPAC_CIAAW-Isotopic-Abundances-and-Atomic-Weights/id/> .
@prefix dcterms: <http://purl.org/dc/terms/> .
@prefix element: <https://hendrikborgelt.github.io/Draft_for_IUPAC_CIAAW-Isotopic-Abundances-and-Atomic-Weights/elements/> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix qudt: <http://qudt.org/schema/qudt/> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix skos: <http://www.w3.org/2004/02/skos/core#> .
@prefix unit: <http://qudt.org/vocab/unit/> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

ciaaw:note-g a ciaaw:Footnote ;
    skos:definition "Geological and biological materials are known in which the element has an isotopic composition outside the limits for normal material. The difference between the atomic weight of the element in such materials and that given in the table may exceed the stated uncertainty."@en ;
    skos:notation "g" .

ciaaw:note-r a ciaaw:Footnote ;
    skos:definition "Range in isotopic composition of normal terrestrial material prevents a more precise standard atomic weight being given; the tabulated value and uncertainty should be applicable to normal material."@en ;
    skos:notation "r" .

ciaaw_draft:AW-He-standard-1902 a ciaaw:StandardAtomicWeightDeclaration ;
    dcterms:isReplacedBy ciaaw_draft:AW-He-standard-1911 ;
    dcterms:issued "1902"^^xsd:gYear ;
    dcterms:source <https://doi.org/10.1007/BF01370337> ;
    owl:deprecated true ;
    adms:status <http://purl.org/adms/status/Deprecated> ;
    ciaaw:ofElement element:Helium ;
    ciaaw:value [ a qudt:QuantityValue ;
            qudt:hasUnit unit:UNITLESS ;
            qudt:numericValue 4.0 ] .

ciaaw_draft:AW-He-standard a ciaaw:StandardAtomicWeightDeclaration ;
    dcterms:issued "1983"^^xsd:gYear ;
    dcterms:replaces ciaaw_draft:AW-He-standard-1969 ;
    dcterms:source <https://doi.org/10.1351/pac198456060653> ;
    ciaaw:footnote ciaaw:note-g,
        ciaaw:note-r ;
    ciaaw:ofElement element:Helium ;
    ciaaw:value [ a qudt:QuantityValue ;
            qudt:hasUnit unit:UNITLESS ;
            qudt:numericValue 4.002602 ;
            qudt:standardUncertainty 0.000002 ;
            ciaaw:significantFigures 7 ;
            ciaaw:significantFiguresUncertainty 1 ] .

ciaaw_draft:AW-He-standard-1911 a ciaaw:StandardAtomicWeightDeclaration ;
    dcterms:isReplacedBy ciaaw_draft:AW-He-standard-1916 ;
    dcterms:issued "1911"^^xsd:gYear ;
    dcterms:replaces ciaaw_draft:AW-He-standard-1902 ;
    dcterms:source <https://doi.org/10.1021/ja01928a001> ;
    owl:deprecated true ;
    adms:status <http://purl.org/adms/status/Deprecated> ;
    ciaaw:ofElement element:Helium ;
    ciaaw:value [ a qudt:QuantityValue ;
            qudt:hasUnit unit:UNITLESS ;
            qudt:numericValue 3.99 ] .

ciaaw_draft:AW-He-standard-1916 a ciaaw:StandardAtomicWeightDeclaration ;
    dcterms:isReplacedBy ciaaw_draft:AW-He-standard-1931 ;
    dcterms:issued "1916"^^xsd:gYear ;
    dcterms:replaces ciaaw_draft:AW-He-standard-1911 ;
    dcterms:source <https://doi.org/10.1021/ja02176a001> ;
    owl:deprecated true ;
    adms:status <http://purl.org/adms/status/Deprecated> ;
    ciaaw:ofElement element:Helium ;
    ciaaw:value [ a qudt:QuantityValue ;
            qudt:hasUnit unit:UNITLESS ;
            qudt:numericValue 4.00 ] .

ciaaw_draft:AW-He-standard-1931 a ciaaw:StandardAtomicWeightDeclaration ;
    dcterms:isReplacedBy ciaaw_draft:AW-He-standard-1938 ;
    dcterms:issued "1931"^^xsd:gYear ;
    dcterms:replaces ciaaw_draft:AW-He-standard-1916 ;
    dcterms:source <https://doi.org/10.1039/JR9310001617> ;
    owl:deprecated true ;
    adms:status <http://purl.org/adms/status/Deprecated> ;
    ciaaw:ofElement element:Helium ;
    ciaaw:value [ a qudt:QuantityValue ;
            qudt:hasUnit unit:UNITLESS ;
            qudt:numericValue 4.002 ] .

ciaaw_draft:AW-He-standard-1938 a ciaaw:StandardAtomicWeightDeclaration ;
    dcterms:isReplacedBy ciaaw_draft:AW-He-standard-1961 ;
    dcterms:issued "1938"^^xsd:gYear ;
    dcterms:replaces ciaaw_draft:AW-He-standard-1931 ;
    dcterms:source <https://doi.org/10.1039/JR9380001101> ;
    owl:deprecated true ;
    adms:status <http://purl.org/adms/status/Deprecated> ;
    ciaaw:ofElement element:Helium ;
    ciaaw:value [ a qudt:QuantityValue ;
            qudt:hasUnit unit:UNITLESS ;
            qudt:numericValue 4.003 ] .

ciaaw_draft:AW-He-standard-1961 a ciaaw:StandardAtomicWeightDeclaration ;
    dcterms:isReplacedBy ciaaw_draft:AW-He-standard-1969 ;
    dcterms:issued "1961"^^xsd:gYear ;
    dcterms:replaces ciaaw_draft:AW-He-standard-1938 ;
    dcterms:source <https://doi.org/10.1021/ja00881a001> ;
    owl:deprecated true ;
    adms:status <http://purl.org/adms/status/Deprecated> ;
    ciaaw:ofElement element:Helium ;
    ciaaw:value [ a qudt:QuantityValue ;
            qudt:hasUnit unit:UNITLESS ;
            qudt:numericValue 4.0026 ] .

ciaaw_draft:AW-He-standard-1969 a ciaaw:StandardAtomicWeightDeclaration ;
    dcterms:isReplacedBy ciaaw_draft:AW-He-standard ;
    dcterms:issued "1969"^^xsd:gYear ;
    dcterms:replaces ciaaw_draft:AW-He-standard-1961 ;
    dcterms:source <https://doi.org/10.1351/pac197021010091> ;
    owl:deprecated true ;
    adms:status <http://purl.org/adms/status/Deprecated> ;
    ciaaw:ofElement element:Helium ;
    ciaaw:value [ a qudt:QuantityValue ;
            qudt:hasUnit unit:UNITLESS ;
            qudt:numericValue 4.00260 ;
            qudt:standardUncertainty 0.00001 ;
            ciaaw:significantFigures 6 ;
            ciaaw:significantFiguresUncertainty 1 ] .

element:Helium a chemrof:ChemicalElement ;
    rdfs:label "helium"@en ;
    ciaaw:currentStandardAtomicWeight ciaaw_draft:AW-He-standard ;
    ciaaw:hasDeclaration ciaaw_draft:AW-He-standard,
        ciaaw_draft:AW-He-standard-1902,
        ciaaw_draft:AW-He-standard-1911,
        ciaaw_draft:AW-He-standard-1916,
        ciaaw_draft:AW-He-standard-1931,
        ciaaw_draft:AW-He-standard-1938,
        ciaaw_draft:AW-He-standard-1961,
        ciaaw_draft:AW-He-standard-1969 ;
    ciaaw:hasIsotope ciaaw_draft:He-3,
        ciaaw_draft:He-4 ;
    ciaaw:standardAtomicWeightUncertainty 0.000002 ;
    ciaaw:standardAtomicWeightValue 4.002602 ;
    chemrof:atomic_number 2 ;
    chemrof:symbol "He" .
```

[All atomic weights](../atomic-weights.md) · [All isotopic abundances](../isotopic-abundances.md)