Which one of the following properties decreases across the periodic table from left to right and increases from top to bottom?
Ionization energy
Electron affinity
Electronegativity
Atomic radius
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This question was previously asked in
UPSC CAPF – 2021
Across a period (left to right), the atomic radius decreases because the nuclear charge increases while electrons are added to the same energy shell, pulling the electron cloud closer to the nucleus. Down a group (top to bottom), the atomic radius increases because new electron shells are added, increasing the distance between the nucleus and the valence electrons, despite the increased nuclear charge.