Which elements can be diatomic?

Which elements can be diatomic and why?




---


**Motivation**


Hydrogen, Nitrogen, Oxygen and the Halogens tend to be thermodynamically stable as a diatomic molecule at room temperature, and are usually labelled as diatomic nonmetals. (Although I am unsure about Astatine). These are the ones you learn in school and I am fine with their reasoning. I want to know about other elements in particular.


Looking at the rest of the non-metals: [Carbon](http://en.wikipedia.org/wiki/Diatomic_carbon), [Phosphorus](http://en.wikipedia.org/wiki/Diphosphorus) and [Sulfur](http://en.wikipedia.org/wiki/Disulfur) have diatomic molecules in gaseous states. All with a common theme of being heated at very high temperatures.


This leaves us with diatomic Selenium which I could not find anything on.




---


**Further notes**


Diatomicity doesn't seem to be just a non-metal thing:


* Lithium forms diatomic molecules and [all diatomic alkali metals are claimed to be stable in gaseous states](http://2012books.lardbucket.org/books/principles-of-general-chemistry-v1.0/s13-molecular-geometry-and-covalen.html#averill_1.0-ch09_s03_s02_f02). Found from [this question](https://chemistry.stackexchange.com/questions/32686/is-it-possible-to-have-a-diatomic-molecule-of-sodium-in-gaseous-state).
* Silicon [has been reported](http://pubs.acs.org/doi/abs/10.1021/cen-v086n034.p010) to have a diatomic molecule similar in structure to carbon.
* Tungsten, Chromium, Uranium and Molybdenum are [claimed to be diatomic](http://en.wikipedia.org/wiki/Sextuple_bond) with a sextuple bond.
* Supposedly [Noble gases can form dimer molecules](https://chemistry.stackexchange.com/questions/518/do-noble-gasses-besides-helium-form-diatomic-molecules-at-low-temperatures) but if these are considered diatomic is debatable.





> 
> This leaves us with diatomic Selenium which I could not find anything on.
> 
> 
> 


Selenium forms a dimer with bond energy of 79 kcal/mol, according to table 8.6 (page 451) of [Comprehensive Handbook of Chemical Bond Energies](https://books.google.com/books?id=kM3mwD4y_TAC&pg=PA1652&lpg=PA1652&dq=selenium%20dimer&source=bl&ots=2Pk9euhll4&sig=GUJl2Mq5eYx7nos6tDLDlHEmjIM&hl=en&sa=X&ved=0CFgQ6AEwCGoVChMI7veuiJPjyAIVRFcmCh0jqgIB#v=onepage&q=selenium%20dimer&f=false), which provides 5 references. 


Tellenium dimer is 61 kcal/mol


Polonium dimer 45 kcal/mol


 4