Periodic trends (such as electronegativity, electron affinity, atomic and ionic radii, and ionization energy) can be understood in terms of Coulomb's law, which is _Fₑ_ = ( _q_ ₁ _q_ ₂)/ _r_ ². For example, consider first ionization energy: Coulomb's law tells us that the greater the nuclear charge ( _q_ ₁) and the shorter the distance between the nucleus and the outermost electron ( _r_ ), the st
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