The first and second ionisation energies (in kJ mol⁻¹) of four elements labeled I, II, III and IV are listed below. Which one is an alkali metal?

IE₁ IE₂
I 2372 5251
II 520 7300
III 900 1760
IV 1680 380

Question

The first and second ionisation energies (in kJ mol⁻¹) of four elements labeled I, II, III and IV are listed below. Which one is an alkali metal?

IE₁	IE₂
I	2372	5251
II	520	7300
III	900	1760
IV	1680	380

Accepted Answer

II. Element II has a significantly lower first ionisation energy compared to the others, which is characteristic of alkali metals. Alkali metals have one electron in their outer shell, making it easier to remove, resulting in lower ionisation energies.

The first and second ionisation energies (in kJ mol⁻¹) of four elements labeled I, II, III and IV are listed below. Which one is an alkali metal? IE₁ IE₂ I 2372 5251 II 520 7300 III 900 1760 IV 1680 380

Solution

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