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Unformatted text preview: classification scheme of the elements
based on their electron configurations.
– Example - Noble Gases
• All of them have completely filled electron shells. – Since they have similar electronic structures, their
chemical properties are similar.
[He] 2s2 2p6
[Ne] 3s2 3p6
[Ar] 4s2 3d10 4p6
[Kr] 5s2 4d10 5p6
[Xe] 6s2 4f14 5d10 6p6 Other
Table 6 1/28/2014 Periodic Trends Atomic Radii 7 1/28/2014 Atomic Radii
• Decreases across a period due to shielding or screening
– Effective nuclear charge, Zeff, experienced by an electron is less than
the actual nuclear charge, Z.
– The inner electrons block the nuclear charge’s effect on the outer
electrons, thereby expanding the orbitals of these outer electrons • Moving across a period, each element has...
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