Source
r/chemistry•
Flo422

Is nitrogen the only element that is most stable in a molecule with itself?

This is not some kind of homework question, I just noticed a pattern, I think.

I have been interested in chemistry for quite some time, and i noticed all nitrogen compounds I know are not the most stable form. This is especially noticable in explosive compounds, but it also happens to be the case for some very simple things like N2O or NO2.

Car manufacturers are using expensive technology to prohibit these compounds entering the atmosphere and the process is exothermic, so it would (should) happen anyway given enough time.

Is there a known reason why N2 is the most stable compound of this element? Is there any other compound containing nitrogen that will not revert to N2 given enough time/heat treatment?

Posted Oct 29, 2020, 11:01 PM UTC

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INTPhoenixAnalytical•

A nitpick maybe, but N2 is not the most stable compound, it is still an element in the form of a homonuclear molecule. As for its stability, N2 owes it to its very strong triple bond.

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LunaLucia2•

It's mostly that there are no stable compounds with oxygen, carbon and most halogens, but nitrogen forms a wide range of thermodynamically stable compounds with other elements, for example ammonia with hydrogen, lithium nitride, alkaline earth metal nitrides magnesium nitride to strontium nitride, uranium nitride, most of the early transition metals form stable nitrides, along with boron, aluminium, silicon, phosphorus, and even fluorine.

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Flo422OP•

You mentioned ammonia with hydrogen, isn't this the stuff that blows up explosively once enough energy is put into starting the reaction?

For lithium nitride it is mentioned (only read short section of wikipedia) it will form ammonia in contact with water, so it will revert to a more stable configuration. As far as I know ammonia will also revert to more stable configuration once the activation energy is supplied.

I don't mean 'stable" as in 'will not destry itself once formed'. I meant to say the lowest potential energy configuration, sorry if I can't explain any better, english is still difficult.

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LunaLucia2•

I did mean the lowest energy configuration. The decomposition of ammonia is endothermic, it takes energy to decompose. Also lithium nitride by itself is stable so it won't "destroy itself once formed", but that doesn't mean that it won't react with anything else. By that measure no compound would be truly stable as there's always something else it will react with.

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TheGreenAlchemist•

Incorrect -- ammonia is lower energy than hydrogen and nitrogen separated. The reaction of hydrogen and nitrogen is exothermic (though a high activation energy).

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