The oxygen isotopes are simple enough to be described by some few selected single-particle degrees of freedom.

• Two out of four stable even-even isotopes exhibit a doubly magic nature, namely \( {}^{22}\mbox{O} \) (\( Z=8 \), \( N=14 \)) and \( {}^{24}\mbox{O} \) (\( Z=8 \), \( N=16 \)).
• The structure of \( {}^{22}\mbox{O} \) and \( {}^{24}\mbox{O} \) is assumed to be governed by the evolution of the \( 1s_{1/2} \) and \( 0d_{5/2} \) one-quasiparticle states.
• The isotopes \( {}^{25}\mbox{O} \), \( {}^{26}\mbox{O} \), \( {}^{27}\mbox{O} \) and \( {}^{28}\mbox{O} \) are outside the drip line, since the \( 0d_{3/2} \) orbit is not bound.