Answer: Na has lower first ionisation energy than Li, making it easier to ionise; also Na reacts exothermically faster.
- A Na has lower first ionisation energy than Li, making it easier to ionise; also Na reacts exothermically faster
- B Lithium is generally a noticeably more electronegative element than sodium in typical laboratory settings
- C Lithium's higher melting point reduces the metal surface area exposed to water under usual circumstances
- D Sodium atoms contain fewer total orbital electrons than lithium atoms do according to most researchers in the majority of cases studied
Correct answer: A. Na has lower first ionisation energy than Li, making it easier to ionise; also Na reacts exothermically faster
Explanation: Li's very high charge density means the Li+ ion is heavily hydrated, releasing more energy overall, but kinetically Li's reaction is slower due to its higher ionisation energy and the coherent film of LiOH.
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.