re: What is the difference between a ChemicalSubstance and a MolecularEntity?

On 2019-06-14 12:36, Jerven Tjalling Bolleman wrote:
> Regarding the request for comments. I would like to see a bit of
> an  explanation what the difference is between a MolecularEntity
> and a ChemicalSubstance.

This distinction loosely follows the ChEBI ontology:

MolecularEntity: Any constitutionally or isotopically distinct atom,
molecule, ion, ion pair, radical, radical ion, complex, conformer etc.,
identifiable as a separately distinguishable entity.

ChemicalSubstance: A chemical substance is a portion of matter of constant
composition, composed of molecular entities of the same type or of
different types.

The need to distinguish this surfaces in various situations. Crystal
structures, for example, are not molecular entities, and protein crystal
structures normally indeed composed of different types of molecular
entities.

> Specifically for ChemicalSubstance I would like to see a description
> on how it relates to the existing schema.org Substance.

The schema.org Substance is a good example of a chemical substance: it is a
medical entity that contains an active ingredient and additional stuff that
makes up a pill, like filling materials, etc.

I'm tempted to say that the schema.org Substance is a subclass of the
ChemicalSubstance.

Another example of chemical substances are nanomaterials, which contains of
a mixture of related molecular entities (but more or less different size,
composition, etc) and sometimes with impurities.

Egon

-- 
Hi, do you like citation networks? Already 51% of all citations are
available <https://i4oc.org/> available for innovative new uses
<https://twitter.com/hashtag/acs2ioc>. Join me in asking the American
Chemical Society to join the Initiative for Open Citations too
<https://www.change.org/p/asking-the-american-chemical-society-to-join-the-initiative-for-open-citations>.
SpringerNature,
the RSC and many others already did <https://i4oc.org/#publishers>.

-----
E.L. Willighagen
Department of Bioinformatics - BiGCaT
Maastricht University (http://www.bigcat.unimaas.nl/)
Homepage: http://egonw.github.com/
Blog: http://chem-bla-ics.blogspot.com/
PubList: https://www.zotero.org/egonw
ORCID: 0000-0001-7542-0286 <http://orcid.org/0000-0001-7542-0286>
ImpactStory: https://impactstory.org/u/egonwillighagen