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Unformatted text preview: an increased
nuclear charge and the electrons are going into the same shell
(2s and 2p or 3s and 3p, etc.).
– Consequently, the outer electrons feel a stronger effective nuclear
charge. Atomic Radii
• Example : Arrange these elements based on
their decreasing atomic radii.
– P, Cl, S, Si
– Ga, F, S, As Less shielded e- ,
valence shell INCREASING ATOMIC SIZE
INCREASING ATOMIC SIZE Since the inner electrons of group 1 and 2 elements represent
the inert gas core (the previous inert gas), they experience the
strongest shielding, therefore the valence electrons expand
outward. More shielded e-,
valence shell Ionic Radii
• Cations (positive ions)
are always smaller than
their respective neutral
Removal of valence electron
leaves the inner core (smaller size) • Anions (negative ions)
are always larger than
their neutral atoms.
Addition of electron into the
valence orbital results in repulsion,
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