In the past somebody showed me the puzzle below. I remember the answer but not the entire solution. Here it goes:

On a grid of 2x2 put four single letter chemical elements. The result should have two letter elements on the horizontal, vertical and diagonal.

  • 1
    $\begingroup$ So, what exactly is the question?? $\endgroup$
    – Sid
    Commented Aug 3, 2016 at 15:34
  • $\begingroup$ Well I thought there should be a element in every direction. So ltr and rtl. By now I know that's impossible. What frustrated me is that there are two possibilities depending on the direction you read the diagonal. $\endgroup$ Commented Aug 3, 2016 at 16:17

5 Answers 5


The answer is:

First row:


Second row:


The elements are:

Sn - Tin, Bi - Bismuth, Sb - Antimony, Ni - Nickel, Si - Silicon, Nb - Niobium

  • $\begingroup$ I've just deleted my comment cause you spotted the diagonals :) $\endgroup$
    – rhsquared
    Commented Aug 3, 2016 at 15:38
  • $\begingroup$ +1 I saw the answer for the diagonal from upper left to lower right, but did not consider the one from lower left to upper right. $\endgroup$
    – Herb
    Commented Aug 3, 2016 at 15:40
  • $\begingroup$ How is this not accepted and the other, later one is accepted? $\endgroup$
    – EKons
    Commented Aug 3, 2016 at 19:01
  • $\begingroup$ @ΈρικΚωνσταντόπουλος both answers are correct if you reverse the reading direction of the diagonal. To me left-to-right seems more logical than top-to-bottem. Although 11 people disagree. Is there a rule of thumb when reading diagonally? I can't find anything about it on the web. $\endgroup$ Commented Aug 3, 2016 at 20:12

Taking a quick look at a period chart, the only valid answer, giving your hint is:



Antimony (Sb)
Tin (Sn)
Silicon (Si) Nickel (Ni)
Bismuth (Bi)

  • $\begingroup$ @PeterJanssen There is no element with the symbol Bn $\endgroup$
    – GoodDeeds
    Commented Aug 3, 2016 at 15:49
  • $\begingroup$ It seems that there is consensus about what direction a diagonal needs to be read. $\endgroup$ Commented Aug 3, 2016 at 16:19
  • 3
    $\begingroup$ Nb is niobium, which isn't explicitly listed in the elements above. $\endgroup$ Commented Aug 3, 2016 at 18:59
  • $\begingroup$ How do you know this is the only answer? (The search space is pretty small, so I suppose exhaustive search would be trivial) $\endgroup$
    – Alexander
    Commented Aug 3, 2016 at 22:47
  • $\begingroup$ The original question had the letters I, s, b, and n in the hint. $\endgroup$
    – Herb
    Commented Aug 3, 2016 at 23:27


S: Sulfur
Si: Silicon
Sb: Antimony
Sn: Tin
I: Iodine
In: Indium
N: Nitrogen
Ni: Nickel
Nb: Niobium
B: Boron
Bi: Bismuth


Row entries: 2
Column entries: 2
Total entries: 4
Additional entries: 11
Other entries: [CHEM_EL] 11 [CHEM_EL_L2] 7
Total: 15
Other tallies: [DUPE] 0


First row:


Second row:


And the elements are:

Scandium (Sc), Cesium (Cs), Nobelium (No), Tin (Sn), Cobalt (Co), Copernicium (CN -diagonal), Osmium (Os - diagonal)

  • $\begingroup$ Kudos for using Cn. Wasn't named when I first heard about this puzzle. $\endgroup$ Commented Aug 4, 2016 at 19:11

My answer is

Sc and In
Sc=Scandium, S=Sulfur, C=Carbon
In=Indium, I=Iodine, N=Nitrogen

  • 4
    $\begingroup$ Neither Ci nor Ic is a chemical element $\endgroup$ Commented Aug 3, 2016 at 17:18
  • $\begingroup$ Welcome to Puzzling.SE! Please double-check the question contents and your answer to see if it is correct. Here, the elements Ci and Ic are specified, but they do not exist. $\endgroup$
    – EKons
    Commented Aug 3, 2016 at 19:03

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.