Series04PeriodicTrends

Series04PeriodicTrends - Trends in the Periodic Table...

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Trends in the Periodic Table Reading: Gray: (2-2) to (2-4) and (2-9) OGC: (3.1), (3.3), (3.4) and (5.2) to (5.5) IV-1
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Now We Can Understand Arrangement of the Periodic Table of Elements Trends in Atomic Size Trends in Ionization Energy Trends in Electron Affinity Trends in Electronegativity Various Types of Chemical Bonds Combining Ratios of Oxides and Hydrides Shapes of Molecules IV-2
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Invented the periodic table in 1869. Also in that year, he published his book, "Principles of Chemistry." His book compared the atomic weights and the properties of elements that were not known back then. 1906: One vote away from winning a Nobel Prize Died in 1907 Dmitri Mendeleev St. Petersburg University IV-3
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 0 20 40 60 80 Solid-State Molar Volumes ( ) 3D Molar volume ( ) cm 3 mol Cs Ba H He Rn Sr Y Lu Sc Ti V Cr Zr Hf Ta W Nb Mo Re Os Ir Pt Au Hg Tl Pb Bi Po Rb K Ca Na Mg Al Si P S Cl Ar Li Be Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Mn Fe Co Zn Ga Ni Cu Ge As Se Br Kr B O N C F Ne At In 1875, Lothar Meyer deduces a periodic trend IV-4
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* E(eV) 0 -13.6 16 -13.6 9 -13.6 4 -13.6 1 (vacuum energy) 1s 2s 2p 3s 3p 4s 4p 4f 4d 3d Energy of One Electron in a H atom * E = -k n 2 where k=13.6 eV; n is the principal quantum number IV-5
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On Average, Z eff < Z How Much Less Z eff < Z Determines Atomic Properties Multiple-Electron Atoms None of the e - eclipsed: Z eff = Z One e - eclipsed: Z eff = Z - 1 IV-6
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+ + + + z x r 2 R 2 1s 2s r 2 R 2 1s 2p IV-7
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An electron in the 2p orbital penetrates somewhat into the 1s orbital Shielding r 2 R 2 r 2 R 2 = probability of finding an electron on the sphere of radius r 1s 2p 2s r IV-8
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Shielding But a 2s electron penetrates the 1s orbital better than a 2p electron r 2 R 2 r 2 R 2 = probability of finding an electron on the sphere of radius r 1s 2p 2s r IV-9
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Shielding A 3s electron penetrates the 1s orbital better than a 3p electron r 2 R 2 r 1s 3d 3p 3s Penetration: 3s > 3p > 3d IV-10
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Shielding A 4s electron penetrates the 1s orbital better than a 4p electron r 2 R 2 r Penetration: 4s > 4p > 4d > 4f 1s 4f 4d 4s 4p IV-11
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Another View of 2s vs 2p Shielding 1s 2p shielded electron density 1s 2s 2s Penetrates More into 1s Than Does 2p 2s is Therefore Lower in E Than 2p IV-12
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1s 2s 2p 3s 3p 5s 4p 3d Energy of Multi-Electron Atoms 4s E (e t c.) 0 due to shielding, orbitals with the same principal quantum number( n ) do NOT have the same energies IV-13
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1s 2s 3s 4s 5s 2p 3p 4p 5p 3d 4d 5d 4f 5f Mnemonic for Filling Order hence the filling order is: 1s, 2s, 2p, 3s, 3p, 4s, 3d, etc. IV-14
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