CCNYChem103_quantumtheory part2-3.ppt

The remaining four electrons are placed in the ℓ 1

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The remaining four electrons are placed in the ℓ = 1 subshell, which contains three 2 p orbitals. The orbital diagram is
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7.11 The results are summarized in the following table: •Note that each electron in the orbital diagram has a unique set of quantum numbers. •The placement of the eighth electron in the orbital labeled m = 1 is arbitrary. It would be equally correct to assign it to m = 0 or m = −1.
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49 Outermost subshell being filled with electrons
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50 An s orbitals hold two electrons Three p orbitals hold 6 electrons (3x2) Five d orbitals hold 10 electrons (5x2)
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Abbreviated electron configurations Abbreviated electron configurations emphasize the similarity of the configurations of elements in the same group. Group 1: Li: [He]2s 1 Na: [Ne]3s 1 K: [Ar]4s 1 Group 2: Be: [He]2s 2 Mg: [Ne]3s 2 Ca: [Ar]4s 2
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Electron configuration exceptions There are some exceptions to the order of filling subshells. Examples: Cu and Cr There is stability associated with a half-filled or fully filled d subshell. An electron shifts from the 4 s into the 3 d subshell to achieve this stability. Cu: Expect: [Ar]4s 2 3d 9 Actual: [Ar]4s 1 3d 10 Cr Expect: [Ar]4s 2 3d 4 Actual: [Ar]4s 1 3d 5
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Electron configuration exceptions There are some exceptions to the order of filling subshells. Examples: Cu and Cr There is stability associated with a half-filled or fully filled d subshell. An electron shifts from the 4 s into the 3 d subshell to achieve this stability. Cu: Expect: [Ar]4s 2 3d 9 Actual: [Ar]4s 1 3d 10 Cr Expect: [Ar]4s 2 3d 4 Actual: [Ar]4s 1 3d 5
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Electron configurations and the periodic table The periodic table arranges atoms so that elements with the same chemical and physical properties are in the same group. Elements in the same group have similar valence electron configurations. Valence electrons play the most important role in chemical reactions. This describes why elements in the same group have similar chemical reactivity.
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Electron configurations and the periodic table Main group elements or representative elements are those in which the last electron added enters an s or a p orbital in the outermost shell. The valence electrons for main group elements are those with the highest n level. Example Gallium (Ga): [Ar]4s 2 3d 10 4p 1 Ga has three valence electrons (4s 2 and 4p 1 ). The completely filled 3d orbitals count as core, not valence electrons.
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56 Paramagnetic unpaired electrons 2p Diamagnetic all electrons paired 2p Paramagnetic vs. diamagnetic
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Example 7.12 Write the ground-state electron configurations for (a)sulfur (S) (b)palladium (Pd), which is diamagnetic.
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Example 7.12 Solution Sulfur has 16 electrons. The noble gas core in this case is [Ne]. (Ne is the noble gas in the period preceding sulfur.) [Ne] represents 1 s 2 2 s 2 2 p 6 . This leaves us 6 electrons to fill the 3 s subshell and partially fill the 3 p subshell.
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  • Spring '17
  • Glen
  • Atom, Atomic orbital

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