CH 101 notes 9-7

CH 101 notes 9-7 - Valence electrons The periodicity of the...

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The periodicity of the chemical properties results from the periodicity in the valence electron configurations. Valence electrons Section 3.1 In something closer to English: As one moves across a row of the periodic table, the chemical properties of each element change gradually. The changes are the result of changes in the number of valence electrons. Z eff = Z - σ Attraction to nucleus felt by electron # protons in nucleus Shielding constant Z eff ~ Z σ & Effective Nuclear Charge σ inner σ outershell Section 3.2 Z eff ~ Z - inner + σ outershell ) Z eff Z ~ H: 1 p + & 1 st e - Z eff Z ~ He: 2 p + & 2 nd e - σ outershel - Z eff Z ~ Li: 3 p + & 3 rd e - σ inner - Z eff Z ~ Be: 4 p + & 4 th e - ( σ inner + σ outershel ) - Z eff Z ~ B: 5 p + & 5 th e - ( σ inner + σ outershell ) - Z eff Z ~ C: 6 p + & 6 th e - ( σ inner + σ outershel ) - Z eff Z ~ N: 7 p + & 7 th e - ( σ inner + σ outershell ) - Z eff Z ~ O: 8 p + & 8 th e - ( σ inner + σ outershell ) - Z eff Z ~ F: 9 p + & 9 th e - ( σ inner + σ outershell ) - Z eff Z ~ Ne: 10 p + & 10 th e - ( σ inner + σ outershell ) - Z eff Z ~ Na: 11 p + & 11 th e - σ inner - 1 1 1.7 1.3 2.0 2.6 3.3 3.9 4.6 5.2 5.9 2.2 Section 3.2 2 3 4 5 6 7 8 9 10 + + + + + + + + + + + 11 Z eff ~ Z - inner + σ outershell ) 1 Section 3.2 2 3 4 5 6 7 8 9 10 + + + + + + + + + + + 11 Z eff =10.7 Z eff =2.2 Z eff Trends smallest largest Metals Non- metals Section 3.2 The Periodic Table and Atomic Size, Orbital Energy, Electronegativity and Ionization Energy Energy ~ - Z 2 eff n 2 n 2 Radius (atomic size) Z eff ~ Electronegativity ~ + Z 2 eff n 2 Ionization Energy ~ + Z 2 eff n 2
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Metals Non- metals Summary Small High EN (except noble gas) High IE Large
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CH 101 notes 9-7 - Valence electrons The periodicity of the...

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