Same chapter3 marksDifficulty: Medium
Why does the atomic radius of the noble gases appear larger than that of the halogen before them?
Classification of Elements and Periodicity in Properties
3 marksDifficulty: Medium
Explain why the first ionisation enthalpy of nitrogen is greater than that of oxygen.
Original Khojo Papers practice question — not from a past board paper.
Answer
Nitrogen has the configuration 1s22s22p3, with a half-filled 2p subshell, which is unusually stable. Oxygen has 2p4, and removing the paired electron relieves the repulsion between the two electrons in one orbital, so less energy is needed.
No citable source has been recorded for this record. Treat it as practice material, not as fact.
Explanation
The same reasoning explains the dip from phosphorus to sulphur.
Related questions
From the same topic and chapter, at a similar level.
Same chapter3 marksDifficulty: Medium
Why is the second ionisation enthalpy of an element always greater than the first?
Classification of Elements and Periodicity in Properties
Same chapter3 marksDifficulty: Medium
Define electronegativity and state how it varies in the periodic table.
Classification of Elements and Periodicity in Properties
Same chapter3 marksDifficulty: Medium
Arrange Na+, Mg2+, F− and O2− in order of increasing ionic radius and give the reason.
Classification of Elements and Periodicity in Properties
Same subject3 marksDifficulty: Medium
State Hund's rule and the Aufbau principle.
Structure of Atom
Same subject3 marksDifficulty: Medium
A compound contains 40% carbon, 6.7% hydrogen and 53.3% oxygen. Its molar mass is 180 g. Find its empirical and molecular formulae.
Some Basic Concepts of Chemistry