Lacey_Che131_F2017_Lect-25s.pdf

Lacey_Che131_F2017_Lect-25s.pdf - Electron Configurations K...

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10/25/2017 1 Roy A. Lacey, Stony Brook University; Che 131, Fall 2017 1 Lect-25: Periodic Trends Roy A. Lacey, Stony Brook University; Che 131, Fall 2017 2 Electron Configurations K 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 or [ Ar ]4s 1 V 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 3 or [ Ar ]4s 2 3d 3 Cr 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 5 or [ Ar ]4s 1 3d 5 Mn 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 5 or [ Ar ]4s 2 3d 5 Cu 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 10 or [ Ar ]4s 1 3d 10 Remember tha t; 3d orbitals are more compact than 4s, and as a result any electrons entering 3d orbitals will experience greater mutual repulsion The relevant s orbital can relieve such additional electron-electron repulsion Roy A. Lacey, Stony Brook University; Che 131, Fall 2017 3 Anomalous electronic configurations Chromium [Ar] 3d 5 4s 1 Copper [Ar] 3d 10 4s 1 Niobium [Kr] 4d 4 5s 1 Molybdenum [Kr] 4d 5 5s 1 Ruthenium [Kr] 4d 7 5s 1 Rhodium [Kr] 4d 8 5s 1 Palladium [Kr] 4d 10 5s 0 Silver [Kr] 4d 10 5s 1 Lanthanum [Xe] 5d 1 6s 2 Cerium [Xe] 4f 1 5d 1 6s 2 Gadolinium [Xe] 4f 7 5d 1 6s 2 Platinum [Xe] 4f 14 5d 9 6s 1 Gold [Xe] 4f 14 5d 10 6s 1 Actinium [Rn] 6d 1 7s 2 Thorium [Rn] 6d 2 7s 2 Protactinium [Rn] 5f 2 6d 1 7s 2 Uranium [Rn] 5f 3 6d 1 7s 2 Neptunium [Rn] 5f 4 6d 1 7s 2 Curium [Rn] 5f 7 6d 1 7s 2 Although the relevant s orbital can relieve the electron-electron repulsions in the d orbital, this will depend on the details of the set of interactions between the electrons and the nucleus as well as between the electrons themselves The most stable configuration for atoms of chromium, copper, niobium, molybdenum, ruthenium, rhodium, silver, platinum and gold involves only moving one electron into an s orbital Sc 3+ 1s 2 , 2s 2 , 2p 6 , 3s 2 , 3p 6 Sc 2+ 1s 2 , 2s 2 , 2p 6 , 3s 2 , 3p 6 , 3d 1 Sc 1+ 1s 2 , 2s 2 , 2p 6 , 3s 2 , 3p 6 , 3d 1 , 4s 1 Sc 1s 2 , 2s 2 , 2p 6 , 3s 2 , 3p 6 , 3d 1 , 4s 2 Although the relevant s orbital can Roy A. Lacey, Stony Brook University; Che 131, Fall 2017 4 Electron Configuration of ions ` Start with the configuration for the neutral atom; then add or remove electrons from the valence shells to make the desired ion. (In general, remove electrons with the highest value of n first.) ` Atoms or ions that are isoelectronic with each other have identical numbers and configurations of electrons.
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10/25/2017 2 Roy A. Lacey, Stony Brook University; Che 131, Fall 2017 5 Electron Configuration of ions The electron configuration for I - is [Kr]5s 2 4d 10 5p 6 Roy A. Lacey, Stony Brook University; Che 131, Fall 2017 6
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