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Explain why the first ionisation energy of oxygen is lower than that of nitrogen despite the general increase in values across the second period of the periodic table - Leaving Cert Chemistry - Question c-d - 2016
Question c-d
Explain why the first ionisation energy of oxygen is lower than that of nitrogen despite the general increase in values across the second period of the periodic tabl... show full transcript
Worked Solution & Example Answer:Explain why the first ionisation energy of oxygen is lower than that of nitrogen despite the general increase in values across the second period of the periodic table - Leaving Cert Chemistry - Question c-d - 2016
Step 1
Explain why the first ionisation energy of oxygen is lower than that of nitrogen despite the general increase in values across the second period of the periodic table.
Answer
The first ionisation energy of oxygen is lower than that of nitrogen due to the electronic configuration and stability of the atoms. Nitrogen has a half-filled 2p sublevel, which is relatively stable. In contrast, oxygen does not have a half-filled sublevel and is less stable. Therefore, it requires less energy to remove an electron from oxygen compared to nitrogen.
Step 2
Distinguish between sigma and pi covalent bonding.
Answer
Sigma (σ) bonds are formed first and involve head-on overlap of atomic orbitals, allowing for free rotation around the bond axis. Pi (π) bonds are formed from the sidewise overlap of p orbitals and do not allow for rotation around the bond axis.
In summary:
- Sigma (σ) bonds allow for rotation and are formed from direct overlaps.
- Pi (π) bonds restrict rotation and are formed from lateral overlaps of p orbitals.