I have partitioned the chemical elements into two groups based on a certain occult property that is shared by some of them, but not by the remaining ones.

The following elements have my occult property:

arsenic, astatine, carbon, iron, krypton, neon, phosphorus, silicon, tin

The following elements do not have my occult property:

antimony, boron, cobalt, germanium, gold, helium, lead, mercury, sulfur

Which of the following elements have this occult property?

aluminium, fluorine, francium, gallium, oxygen, polonium.

  • 2
    $\begingroup$ There's nothing immediately obvious about the numerical stats and I can't find any pattern in name origins. $\endgroup$ Feb 25, 2015 at 19:44
  • $\begingroup$ For solving this puzzle, you need nothing except a table with the periodic system. $\endgroup$
    – Alexis
    Feb 26, 2015 at 17:05
  • $\begingroup$ So that means it's the atomic number, abbreviation, name, physical location on the table, or group. $\endgroup$ Feb 26, 2015 at 17:12
  • $\begingroup$ @Engineer Toast Yes, that covers all the information you need. $\endgroup$
    – Alexis
    Feb 26, 2015 at 17:14

1 Answer 1


The answer is

none of them

because the enigmatic property is

the ability to spell the element's name using element symbols. For example, Arsenic is Ar+Se+Ni+C, and Silver is Si+Lv+Er. As far as I can tell, there are only 13 elements with this property: Silver, Arsenic, Astatine, Bismuth, Carbon, Copper, Iron, Krypton, Neon, Phosphorus, Silicon, Tin, and Xenon.

  • $\begingroup$ Any disbelievers can try it out here: bgreco.net/periodic $\endgroup$ Feb 26, 2015 at 22:02
  • $\begingroup$ I'm glad I wrote my own script, because it's not often that I write a recursive function that works on the first try! $\endgroup$
    – DevOfZot
    Feb 26, 2015 at 22:27
  • $\begingroup$ Regular expressions are not always the answer, but sometimes they really are the right tool for the job: refiddle.com/26d7 $\endgroup$
    – waxwing
    Feb 27, 2015 at 7:17

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