Question

Why cesium has less ionization energy than francium

Answer 1

Answer:

Francium has a slightly higher ionization energy than caesium, 392.811(4) kJ/mol as opposed to 375.7041(2) kJ/mol for caesium. Due to lanthenoid contraction size of Cs and Fr are almost equal.. hence ionization energies are almost same.. since Fr is radioactive we not study it in group 1.