上海交通大学：《大学化学》教学资源_加州理工课件学习_Series04PeriodicTrends

Trends in the Periodic Table Reading:Gray:(2-2)to (2-4)and(2-9) 0GC:(3.1),(3.3),(3.4)and(5.2)to(5.5) IV-1

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

Now We Can Understand Arrangement of the Periodic Table of Elements ·Trends in Atomic Size Trends in lonization Energy Trends in Electron Affinity Trends in Electronegativity Various Types of Chemical Bonds Combining Ratios of Oxides and Hydrides Shapes of Molecules IV-2

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

Dmitri Mendeleev St.Petersburg University 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 IV-3

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

Solid-State Molar Volumes (3D) He Ne Na Julius Lothar Meyer B Mg S CI 80 Cs Ca Al Si P K Sr 60 So Ti V Cr Mn Fe Co Ni CuZn Ga Ge As Sel Rn Ba Y In S SnSb Te 40 Zr Nb Mo TeRu Rh Pd Ag Cd Molar volume 20> Lu Hf Ta WReOs Ir Pt Au Ha TI Pb Bi Po cm3 mol 0 123 45 6789101112131415161718 In 1875,Lothar Meyer deduces a periodic trend IV-4

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 ( ) cm3 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 N O C F Ne At In 1875, Lothar Meyer deduces a periodic trend IV-4

Energy of One Electron in a H atom E(eV) 0- (vacuum energy) -13.6 16 4s 4p 4d 4f -13.6 9 3d -13.6 4 2p where k=13.6 eV; E = 水 n2 n is the principal -13.6 quantum number 1 IV-5

* E(eV) 0 -13.6 16 -13.6 9 -13.6 4 -13.6 1 (vacuum energy) 1s 2s 2p 3s 3p 4s 4p 4d 4f 3d Energy of One Electron in a H atom * E = -k n2 where k=13.6 eV; n is the principal quantum number IV-5

Multiple-Electron Atoms None of the e eclipsed:Zef=Z 0 One e eclipsed:Zef =Z-1 On Average,Zeft<Z How Much Less Zeff Z Determines Atomic Properties IV-6

On Average, Zeff < Z How Much Less Zeff < Z Determines Atomic Properties Multiple-Electron Atoms None of the e- eclipsed: Zeff = Z One e- eclipsed: Zeff = Z - 1 IV-6

rR2 2s + rR2 2P 1S ◆ IV-7

+ + – – – – – – – + + z x r2R2 1s 2s r2R2 1s 2p IV-7

Shielding r2R2 2p 2s 1s r2R2 probability of finding an electron on the sphere of radius r r An electron in the 2p orbital penetrates somewhat into the 1s orbital IV-8

An electron in the 2p orbital penetrates somewhat into the 1s orbital Shielding r2R2 r2R2 = probability of finding an electron on the sphere of radius r 1s 2p 2s r IV-8

Shielding r2R2 2P 2s 1s r2R2 probability of finding an electron on the sphere of radius r r But a 2s electron penetrates the 1s orbital better than a 2p electron IV-9

Shielding But a 2s electron penetrates the 1s orbital better than a 2p electron r2R2 r2R2 = probability of finding an electron on the sphere of radius r 1s 2p 2s r IV-9

Shielding r2R2 1s 3d 3P39 Penetration: 3s>3p>3d r A 3s electron penetrates the 1s orbital better than a 3p electron IV-10

Shielding A 3s electron penetrates the 1s orbital better than a 3p electron r2R2 r 1s 3d 3p 3s Penetration: 3s > 3p > 3d IV-10