Here's my thinking:
Atomic oxygen in its ground state is a free radical because there are two unpaired electrons in p-orbitals.
When species react new orbitals are formed, and perhaps a situation can occur where the amount of degenerate orbitals is changed by a chemical reaction. This would implicate the filling of these orbitals, following the aufbau principle and hunds rule of filling.
- Therefore it is thinkable that two reactant species (i.e. not homolytic bond fission) which are not radicals, can react in such a way that the new electron orbitals are filled in such a way that all electrons are no longer paired => radical species formed from non-radical species.
- Likewise it is conceivable that a radical species can react with a non-radical species (i.e. not an even number of radical species terminating eachother) to form only non-radical species.
Is my argument and results 3 & 4 correct? Can someone give an example of 3 and/or 4?
Edit: My main takeaway - when considering the feasibility of a radical creation/destruction, look at conservation of spin