Talk:Q578779
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Autodescription — pure substance (Q578779)
description: chemical substance composed of atoms or molecules of only one chemical element or chemical compound
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- View it! – Images depicting the item on Commons
- Report on constraint conformation of “pure substance” claims and statements. Constraints report for items data
For help about classification, see Wikidata:Classification.
- Parent classes (classes of items which contain this one item)
- Subclasses (classes which contain special kinds of items of this class)
- ⟨
pure substance⟩ on wikidata tree visualisation (external tool)(depth=1) - Generic queries for classes
Union and disjoint queries
- Instances of pure substance (Q578779)
that are instances of none of the classes simple substance (Q2512777) and chemical compound (Q11173) [1]
- See also
- This documentation is generated using
{{Item documentation}}.
Difference between chemical compound (Q11173) and pure substance (Q578779)[edit]
What is the difference between chemical compound (Q11173) and pure substance (Q578779) ? Currently the only subclass of pure substance (Q578779) is chemical compound (Q11173), so unless there is at least one other subclass for pure substance (Q578779), chemical compound (Q11173) and pure substance (Q578779) are the same concept. Snipre (talk) 21:01, 17 December 2018 (UTC)
- @Snipre: dioxygen (Q5203615) is an example of pure substance, but not a chemical compound. simple substance (Q2512777) is the second subclass of pure substance (Q578779). However, this classification resembles ChEBI classification, but it's not backed up by all the sources: there are differences on in scientific literature on proper classification of 'chemical substance', 'chemical compound', 'mixture', 'pure substance', 'simple substance', 'elemental substance' and some others. There are of course sources in which some of these concepts are merged into one, in other sources concepts are separated, differently linked to each other, etc. So: this is how ChEBI links these concepts, but it's not the only way. Wostr (talk) 21:29, 17 December 2018 (UTC)
- @Wostr: The problem is that ChEBI never create the link between pure substance and chemical compound so you created a mix of different classifications which can be correct but the definitions must be given and have to coherent. Snipre (talk) 20:47, 19 December 2018 (UTC)
- Example: can a salt wich is a subclass of chemical compound be a lower level of pure substance ? ChEBI definition speaks about molecule when defining pure substance. Is a salt a molecule ? Snipre (talk) 20:58, 19 December 2018 (UTC)
- ChEBI never linked substances and molecules, because it don't have to do it. ChEBI is a database of chemical entities only, WD is a database of everything, so WD cannot be limited to chemical compounds on a molecular level, because we also provide many physical properties for compounds, we link to different concepts, outside chemistry etc. And no, it's not 'a mix of different classifications'. 'Is a salt a molecule' – salt cannot be a molecule, as salt is a substance, i.e. some amount of molecules. And whether 'ion pair' is a molecule... I don't know if there is a simple answer to that question, surely it depends on definitions of more than one concept. Wostr (talk) 21:34, 19 December 2018 (UTC)