The graph plots first ionization energy across period 2. Two anomalies are highlighted in red, where IE1 drops slightly compared to the previous element.
The dip at boron (compared to Be) and oxygen (compared to N) is best explained by:
- Acheck_circle
Removal of an electron from a higher-energy 2p orbital (B) and from a paired 2p orbital (O)
- B
Differences in atomic radius only
- C
Increased shielding by core electrons
- D
A change in nuclear charge magnitude
Explanation
Boron's electron removed comes from 2p (higher energy than Be's 2s); oxygen's first paired 2p electron experiences extra repulsion making it easier to remove.