The hidden facts of a periodic elements and their periodicity:

1. Electronegativity:
Lowest Electronegativity: Cesium (Cs):Cesium, a highly reactive alkali metal, has the lowest electronegativity at 0.79 on the Pauling scale. Its large atomic radius and single valence electron make it highly willing to donate electrons, hence its position as the most electropositive element.
Highest Electronegativity: Fluorine (F):Fluorine, with an electronegativity of 3.98, is the most electronegative element. It has a small atomic size and a strong ability to attract electrons, which makes it highly reactive, especially in forming strong bonds in compounds like HF and in ionic bonds.

2. Ionization Energy:
Highest Ionization Potential: Helium (He): Helium has the highest ionization energy due to its small atomic size and stable electronic configuration. It requires significant energy to remove an electron from its full outer shell.
Lowest Ionization Potential: Cesium (Cs): Cesium has the lowest ionization energy due to its large atomic size and the ease with which it loses its outermost electron, making it highly reactive. 3. Electron Affinity:
Lowest Electron Affinity: Noble Gases: Noble gases like helium, neon, and argon have almost zero electron affinity because their outer electron shells are full, so they do not readily accept electrons.
Highest Electron Affinity: Chlorine (Cl):Chlorine has the highest electron affinity at -349 kJ/mol. It readily accepts an electron to achieve a stable octet configuration, making it a strong oxidizing agent.