O2 is notably stable, particularly when compared to the state where it has lost two electrons (O22+) and those electrons are free. This specific type of stability arises from fundamental energy considerations within the molecule.
Understanding Stability in this Context
In chemistry, stability is often related to energy. A system is considered more thermodynamically stable if it is in a lower energy state. The provided reference explains the stability of O2 relative to O22+ and two free electrons by comparing the total energy of these two different states.
Comparing O2 to O22+ and Free Electrons
Consider the transformation where an O2 molecule loses two electrons to become a positively charged O22+ ion, with the two electrons becoming free. The reference states that O2 is thermodynamically more stable than this resulting state (O22+ plus two free electrons).
The Dominant Energy Factor
According to the reference, the primary reason for this stability difference lies in the energy contribution of the electrons within the O2 molecule. The key factor is:
The decrease in energy caused by the electrons occupying specific orbitals within the O2 molecule (the reference specifically mentions "the highest unoccupied molecular orbitals", though this phrasing is unusual for occupied electrons contributing to stability in this context; the core idea is the energy lowering effect of electrons being bound in O2) is much greater than any possible decrease in the bond energy that might occur when the molecule loses electrons and becomes O22+.
Essentially, having the electrons bound within the O2 molecule in their respective orbitals leads to a significantly lower total energy state compared to the alternative where the molecule is doubly ionized and the electrons are unbound. This large energy difference makes the state of O2 highly favored over the state of O22+ plus free electrons.
Key Factors for This Stability
Based on the reference, the stability of O2 relative to O22+ and free electrons is determined by:
- The significant energy decrease achieved by electrons being bound within the O2 molecular orbitals.
- This energy decrease being substantially greater than any energy changes related to the bond energy when two electrons are removed.
This specific energetic balance is why O2 is thermodynamically stable compared to losing its electrons to become a doubly positive ion.
