How does Abundance or Relative abundance (Chemistry) differs from statistical frequency? Or it is just another term for statistical frequency in context of chemistry?
Update: here are some example
etc.
Are they just statistical frequency? if it is statistical frequency then is it for sample ir population?
N. B. it looks like there are a bunch of related concepts (Probability, Likelyhood, Composition, etc.) which are similar but differ in sense.
Quoting from one of the linked references:
In physics, natural abundance (NA) refers to the abundance of isotopes of a chemical element as naturally found on a planet.
In that context, values of natural abundance are best thought of as representing the "population" of an element over the entire planet. The natural abundance of an isotope of an element is the fraction of atoms of that element (excluding artificially generated atoms produced by human engineering, e.g. via nuclear reactions) that are of that isotope.
So you can think of the natural abundance of an isotope as being the probability that a particular atom of that element is of that isotope.
Of course, any reported value of a natural abundance is based on a sample of that "population."
That said, the reference continues:
The abundance of an isotope varies from planet to planet, and even from place to place on the Earth, but remains relatively constant in time (on a short-term scale).
Thus any particular sample from the population might differ in the observed value of natural abundance.
More generally, relative abundance might refer to the fraction (by mole or mass) of a particular chemical component of a mixture. There's an extensive literature on statistical analysis of such compositional data.
In statistics there's an important distinction between "probability" and "likelihood." See this page and its links for an introduction.
