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

# lanthanum

| Property | Value |
| --- | --- |
| Symbol | La |
| Atomic number | 57 |
| IRI | `https://hendrikborgelt.github.io/Draft_for_IUPAC_CIAAW-Isotopic-Abundances-and-Atomic-Weights/elements/Lanthanum` |
| Wikidata | [Q1801](https://www.wikidata.org/wiki/Q1801) |

## Standard atomic weight

| Value | Year | Source | Status | Declaration |
| --- | --- | --- | --- | --- |
| 138.905 47(7) | 2005 | [10.1351/pac200678112051](https://doi.org/10.1351/pac200678112051) | Current | [`AW-La-standard`](../id/AW-La-standard.md) |
| 138.9055(2) | 1985 | [10.1351/pac198658121677](https://doi.org/10.1351/pac198658121677) | Deprecated, see [`AW-La-standard`](../id/AW-La-standard.md) | [`AW-La-standard-1985`](../id/AW-La-standard-1985.md) |
| 138.9055(3) | 1969 | [10.1351/pac197021010091](https://doi.org/10.1351/pac197021010091) | Deprecated, see [`AW-La-standard-1985`](../id/AW-La-standard-1985.md) | [`AW-La-standard-1969`](../id/AW-La-standard-1969.md) |
| 138.91 | 1961 | [10.1021/ja00881a001](https://doi.org/10.1021/ja00881a001) | Deprecated, see [`AW-La-standard-1969`](../id/AW-La-standard-1969.md) | [`AW-La-standard-1961`](../id/AW-La-standard-1961.md) |
| 138.92 | 1933 | [10.1039/JR9330000354](https://doi.org/10.1039/JR9330000354) | Deprecated, see [`AW-La-standard-1961`](../id/AW-La-standard-1961.md) | [`AW-La-standard-1933`](../id/AW-La-standard-1933.md) |
| 138.90 | 1925 | [10.1039/CT9252700913](https://doi.org/10.1039/CT9252700913) | Deprecated, see [`AW-La-standard-1933`](../id/AW-La-standard-1933.md) | [`AW-La-standard-1925`](../id/AW-La-standard-1925.md) |
| 139 | 1909 | [10.1021/ja01931a001](https://doi.org/10.1021/ja01931a001) | Deprecated, see [`AW-La-standard-1925`](../id/AW-La-standard-1925.md) | [`AW-La-standard-1909`](../id/AW-La-standard-1909.md) |
| 138.9 | 1903 | [10.1021/ja02003a001](https://doi.org/10.1021/ja02003a001) | Deprecated, see [`AW-La-standard-1909`](../id/AW-La-standard-1909.md) | [`AW-La-standard-1903`](../id/AW-La-standard-1903.md) |
| 138 | 1902 | [10.1007/BF01370337](https://doi.org/10.1007/BF01370337) | Deprecated, see [`AW-La-standard-1903`](../id/AW-La-standard-1903.md) | [`AW-La-standard-1902`](../id/AW-La-standard-1902.md) |

Notes: [g](#note-g)

## Isotopes

| A | Representative isotopic composition | Year | Source | Declaration | ChEBI | Wikidata |
| --- | --- | --- | --- | --- | --- | --- |
| [138](../id/La-138.md) | 0.000 8881(71) | — | — | [`Abundance-La138`](../id/Abundance-La138.md) | — | [Q1967612](https://www.wikidata.org/wiki/Q1967612) |
| [139](../id/La-139.md) | 0.999 1119(71) | — | — | [`Abundance-La139`](../id/Abundance-La139.md) | — | [Q2424900](https://www.wikidata.org/wiki/Q2424900) |

Notes: [g](#note-g)

## 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.

## Bibliography

<div class="csl-bib-body">
<div class="csl-entry">Aston, F. W., Baxter, G. P., Brauner, B., Debierne, A., Leduc, A., Richards, T. W., Soddy, F., &#38; Urbain, G. (1925). Second Report of the International Committee of the International Union of Pure and Applied Chemistry on the chemical elements. International atomic weights, 1925. <i>Journal of the Chemical Society, Transactions</i>, <i>127</i>, 913. https://doi.org/10.1039/ct9252700913 <a href="https://doi.org/10.1039/CT9252700913">CrossRef</a> <a href="https://qlever.scholia.wiki/doi/10.1039/CT9252700913">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">Atomic weights of the elements 1985. (1986). <i>Pure and Applied Chemistry</i>, <i>58</i>(12), 1677–1692. https://doi.org/10.1351/pac198658121677 <a href="https://doi.org/10.1351/pac198658121677">CrossRef</a> <a href="https://qlever.scholia.wiki/doi/10.1351/pac198658121677">Scholia</a></div>
<div class="csl-entry">Baxter, G. P., Curie, Mme. P., Lebeau, P., Hönigschmid, O., &#38; Meyer, R. J. (1933). Third Report of the Committee on Atomic Weights of the International Union of Chemistry. <i>J. Chem. Soc.</i>, <i>0</i>(0), 354–361. https://doi.org/10.1039/jr9330000354 <a href="https://doi.org/10.1039/JR9330000354">CrossRef</a> <a href="https://qlever.scholia.wiki/doi/10.1039/JR9330000354">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. (1903). REPORT OF THE INTERNATIONAL COMMITTEE ON ATOMIC WEIGHTS. <i>Journal of the American Chemical Society</i>, <i>25</i>(1), 1–5. https://doi.org/10.1021/ja02003a001 <a href="https://doi.org/10.1021/ja02003a001">CrossRef</a> <a href="https://qlever.scholia.wiki/doi/10.1021/ja02003a001">Scholia</a></div>
<div class="csl-entry">Clarke, F. W., Ostwald, W., Thorpe, T. E., &#38; Urbain, G. (1909). REPORT OF THE INTERNATIONAL COMMITTEE ON ATOMIC WEIGHTS. 1909. <i>Journal of the American Chemical Society</i>, <i>31</i>(1), 1–6. https://doi.org/10.1021/ja01931a001 <a href="https://doi.org/10.1021/ja01931a001">CrossRef</a> <a href="https://qlever.scholia.wiki/doi/10.1021/ja01931a001">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 class="csl-entry">Wieser, M. E. (2006). Atomic weights of the elements 2005 (IUPAC Technical Report). <i>Pure and Applied Chemistry</i>, <i>78</i>(11), 2051–2066. https://doi.org/10.1351/pac200678112051 <a href="https://doi.org/10.1351/pac200678112051">CrossRef</a> <a href="https://qlever.scholia.wiki/doi/10.1351/pac200678112051">Scholia</a></div>
</div>

## Turtle

This resource as a file: [Lanthanum.ttl](Lanthanum.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_draft:AW-La-standard-1902 a ciaaw:StandardAtomicWeightDeclaration ;
    dcterms:isReplacedBy ciaaw_draft:AW-La-standard-1903 ;
    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:Lanthanum ;
    ciaaw:value [ a qudt:QuantityValue ;
            qudt:hasUnit unit:UNITLESS ;
            qudt:numericValue 138.0 ] .

ciaaw_draft:AW-La-standard a ciaaw:StandardAtomicWeightDeclaration ;
    dcterms:issued "2005"^^xsd:gYear ;
    dcterms:replaces ciaaw_draft:AW-La-standard-1985 ;
    dcterms:source <https://doi.org/10.1351/pac200678112051> ;
    ciaaw:footnote ciaaw:note-g ;
    ciaaw:ofElement element:Lanthanum ;
    ciaaw:value [ a qudt:QuantityValue ;
            qudt:hasUnit unit:UNITLESS ;
            qudt:numericValue 138.90547 ;
            qudt:standardUncertainty 0.00007 ;
            ciaaw:significantFigures 8 ;
            ciaaw:significantFiguresUncertainty 1 ] .

ciaaw_draft:AW-La-standard-1903 a ciaaw:StandardAtomicWeightDeclaration ;
    dcterms:isReplacedBy ciaaw_draft:AW-La-standard-1909 ;
    dcterms:issued "1903"^^xsd:gYear ;
    dcterms:replaces ciaaw_draft:AW-La-standard-1902 ;
    dcterms:source <https://doi.org/10.1021/ja02003a001> ;
    owl:deprecated true ;
    adms:status <http://purl.org/adms/status/Deprecated> ;
    ciaaw:ofElement element:Lanthanum ;
    ciaaw:value [ a qudt:QuantityValue ;
            qudt:hasUnit unit:UNITLESS ;
            qudt:numericValue 138.9 ] .

ciaaw_draft:AW-La-standard-1909 a ciaaw:StandardAtomicWeightDeclaration ;
    dcterms:isReplacedBy ciaaw_draft:AW-La-standard-1925 ;
    dcterms:issued "1909"^^xsd:gYear ;
    dcterms:replaces ciaaw_draft:AW-La-standard-1903 ;
    dcterms:source <https://doi.org/10.1021/ja01931a001> ;
    owl:deprecated true ;
    adms:status <http://purl.org/adms/status/Deprecated> ;
    ciaaw:ofElement element:Lanthanum ;
    ciaaw:value [ a qudt:QuantityValue ;
            qudt:hasUnit unit:UNITLESS ;
            qudt:numericValue 139.0 ] .

ciaaw_draft:AW-La-standard-1925 a ciaaw:StandardAtomicWeightDeclaration ;
    dcterms:isReplacedBy ciaaw_draft:AW-La-standard-1933 ;
    dcterms:issued "1925"^^xsd:gYear ;
    dcterms:replaces ciaaw_draft:AW-La-standard-1909 ;
    dcterms:source <https://doi.org/10.1039/CT9252700913> ;
    owl:deprecated true ;
    adms:status <http://purl.org/adms/status/Deprecated> ;
    ciaaw:ofElement element:Lanthanum ;
    ciaaw:value [ a qudt:QuantityValue ;
            qudt:hasUnit unit:UNITLESS ;
            qudt:numericValue 138.90 ] .

ciaaw_draft:AW-La-standard-1933 a ciaaw:StandardAtomicWeightDeclaration ;
    dcterms:isReplacedBy ciaaw_draft:AW-La-standard-1961 ;
    dcterms:issued "1933"^^xsd:gYear ;
    dcterms:replaces ciaaw_draft:AW-La-standard-1925 ;
    dcterms:source <https://doi.org/10.1039/JR9330000354> ;
    owl:deprecated true ;
    adms:status <http://purl.org/adms/status/Deprecated> ;
    ciaaw:ofElement element:Lanthanum ;
    ciaaw:value [ a qudt:QuantityValue ;
            qudt:hasUnit unit:UNITLESS ;
            qudt:numericValue 138.92 ] .

ciaaw_draft:AW-La-standard-1961 a ciaaw:StandardAtomicWeightDeclaration ;
    dcterms:isReplacedBy ciaaw_draft:AW-La-standard-1969 ;
    dcterms:issued "1961"^^xsd:gYear ;
    dcterms:replaces ciaaw_draft:AW-La-standard-1933 ;
    dcterms:source <https://doi.org/10.1021/ja00881a001> ;
    owl:deprecated true ;
    adms:status <http://purl.org/adms/status/Deprecated> ;
    ciaaw:ofElement element:Lanthanum ;
    ciaaw:value [ a qudt:QuantityValue ;
            qudt:hasUnit unit:UNITLESS ;
            qudt:numericValue 138.91 ] .

ciaaw_draft:AW-La-standard-1969 a ciaaw:StandardAtomicWeightDeclaration ;
    dcterms:isReplacedBy ciaaw_draft:AW-La-standard-1985 ;
    dcterms:issued "1969"^^xsd:gYear ;
    dcterms:replaces ciaaw_draft:AW-La-standard-1961 ;
    dcterms:source <https://doi.org/10.1351/pac197021010091> ;
    owl:deprecated true ;
    adms:status <http://purl.org/adms/status/Deprecated> ;
    ciaaw:ofElement element:Lanthanum ;
    ciaaw:value [ a qudt:QuantityValue ;
            qudt:hasUnit unit:UNITLESS ;
            qudt:numericValue 138.9055 ;
            qudt:standardUncertainty 0.0003 ;
            ciaaw:significantFigures 7 ;
            ciaaw:significantFiguresUncertainty 1 ] .

ciaaw_draft:AW-La-standard-1985 a ciaaw:StandardAtomicWeightDeclaration ;
    dcterms:isReplacedBy ciaaw_draft:AW-La-standard ;
    dcterms:issued "1985"^^xsd:gYear ;
    dcterms:replaces ciaaw_draft:AW-La-standard-1969 ;
    dcterms:source <https://doi.org/10.1351/pac198658121677> ;
    owl:deprecated true ;
    adms:status <http://purl.org/adms/status/Deprecated> ;
    ciaaw:ofElement element:Lanthanum ;
    ciaaw:value [ a qudt:QuantityValue ;
            qudt:hasUnit unit:UNITLESS ;
            qudt:numericValue 138.9055 ;
            qudt:standardUncertainty 0.0002 ;
            ciaaw:significantFigures 7 ;
            ciaaw:significantFiguresUncertainty 1 ] .

element:Lanthanum a chemrof:ChemicalElement ;
    rdfs:label "lanthanum"@en ;
    ciaaw:currentStandardAtomicWeight ciaaw_draft:AW-La-standard ;
    ciaaw:hasDeclaration ciaaw_draft:AW-La-standard,
        ciaaw_draft:AW-La-standard-1902,
        ciaaw_draft:AW-La-standard-1903,
        ciaaw_draft:AW-La-standard-1909,
        ciaaw_draft:AW-La-standard-1925,
        ciaaw_draft:AW-La-standard-1933,
        ciaaw_draft:AW-La-standard-1961,
        ciaaw_draft:AW-La-standard-1969,
        ciaaw_draft:AW-La-standard-1985 ;
    ciaaw:hasIsotope ciaaw_draft:La-138,
        ciaaw_draft:La-139 ;
    ciaaw:standardAtomicWeightUncertainty 0.00007 ;
    ciaaw:standardAtomicWeightValue 138.90547 ;
    chemrof:atomic_number 57 ;
    chemrof:symbol "La" .
```

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