# Why does oxygen occur as O_2, and nitrogen as N_2?

Nov 1, 2016

Because the $\text{oxygen atom}$ is unstable with respect to the $\text{oxygen molecule}$, and likewise for the $\text{nitrogen atom}$.
The stable forms of the element are $\text{dioxygen}$ and $\text{dinitrogen}$. Of course, we can form the atoms of each element, however, we would have to expend considerable energy to do so, i.e. we would to have to break strong element-element bonds:
$O = O + \Delta \rightarrow 2 O$ etc.
Under certain circumstances, bent, triatomic ozone can form, but these are exceptional, ${O}_{3} {\equiv}^{-} O - {O}^{+} = O$.