Answer: Li ions are small, and Li 3 N has high lattice energy (similar to Mg).
- A Li ions are small, and Li<sub>3</sub>N has high lattice energy (similar to Mg)
- B Lithium is simply the most reactive metal within the alkali metal family
- C Lithium has the highest first ionisation energy among the alkali metals
- D Lithium displays amphoteric behaviour unlike the other alkali metals
Correct answer: A. Li ions are small, and Li<sub>3</sub>N has high lattice energy (similar to Mg)
Explanation: Li + N<sub>2</sub> → Li<sub>3</sub>N (lithium nitride); Li's small size allows formation of a stable nitride like Mg (diagonal relationship).
Each s-block metal ion emits a characteristic flame colour because heating excites electrons to higher energy levels; light is emitted as they fall back, with the colour determined by the specific energy gap.
Concept context
Group 1 (alkali metals) and Group 2 (alkaline earth metals). Learn their reactions with water and air, important compounds like NaOH, Na₂CO₃, and CaCO₃, and anomalous behaviour of lithium and beryllium.