Which elements can be diatomic and why?
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.
This leaves us with diatomic Selenium which I could not find anything on.
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. Found from this question.
- Silicon has been reported to have a diatomic molecule similar in structure to carbon.
- Tungsten, Chromium, Uranium and Molybdenum are claimed to be diatomic with a sextuple bond.
- Supposedly Noble gases can form dimer molecules but if these are considered diatomic is debatable.