Reading the SI (and ISO) standard for units and quantities, I'm currently puzzled by something very subtle.
If I can see and understand why we talk about scalars, vectors, and tensors in the context of physics quantities (because we fundamentally talk about space-time, geometry, and systems of coordinates), it does not seem as trivial to me for the quantity "amount of substance" (unit mol) that originally comes from chemistry (and which does not seem related to vector spaces or coordinate systems).
Could someone clarify that from a very (very) pedantic standpoint (ideally with sources/citations that would talk about this question)?
Important addition regarding the context: According to BIPM/JCGM: units of measurements are "real scalar quantity, defined and adopted by convention, with which any other quantity of the same kind can be compared to express the ratio of the two quantities as a number". And "amount of substance", is one of the 7 base quantities of SI. And the standard also talk about scalars, vectors, and tensors. The question is raised in this context.