Say you are given a set of particular elements, such as Dy, C, I, Er, P. Is it possible to determine whether a compound exists with all of the given elements and no more?

If not, is it possible to find this out if given the number of a particular element, such as; two hydrogen and one oxygen where you could come to the conclusion that $\ce{H2O}$ is possible.

  • $\begingroup$ are you sure about Dy, Er? $\endgroup$
    – triclosan
    Jul 18, 2013 at 21:08

1 Answer 1


Answer on first question is no, on second is yes.

  1. Consider this short list C, H, O, N this elements can produce unlimited number of compounds.

  2. If you have short formula like C6H6 and you assuming only covalent bonds in molecule, define valence 4 for Carbon and 1 for Hydrogen you can make mathematical calculation according to graph theory and you will get 217 structures. But most of them doesn't exist due to bonds strain and intersection. If you want to obtain existing molecules you can filter this 217 models using for instance quantum mechanics calculation.


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