Modern periodic table question-B

Dear student,

Ionisation energy or ionisation enthalpy is the energy required to remove an electron from the isolated gaseous neutral atom to form a positively charged ion.

First Ionization Energy, energy needed to remove the outermost or highest energy, electron from a neutral atom in the gas phase.

Li $\stackrel{}{\to }$Li⁺  + e^-

Coming to the query,

​Both Li  and F belong to the same period (Period 2).

Electronic configuration of :

• Li : 1s²2s¹
• F : 1s²2s²2p⁵

Lithium can easily lose an electron to acquire stable noble gas configuration of 1s²​​​​​​​ but Fluorine , even though has a small size , has higher electron density of nine electrons in its ultimate or valence shell making it unstable, thus it requires a higher ionisation enthalpy as compared to Lithium to lose an electron from its atom.

Regards.