D. A. Evans Hybridization vs Electronegativity Chem 206 Electrons in 2S states"see" a greater effective nuclear charge than electrons in 2P states There is a linear relationship between %S character This becomes apparent when the radial probability functions for S and P-states are examined the radial probability functions for the hydrogen atom s&p states are show 100% <sORbital oa06∝ X2 S Orbital <2S Orbital C2POrbital A s-Character 3so己→∧ 3POrbitalO/ There is a direct relationship between %S character hydrocarbon acidity S-states have greater radial penetration due to the nodal properties of the wave function. Electrons in S-states""a higher nuclear charge Above observation correctly implies that the stability of nonb pairs is directly proportional to the of S-4 the doubly occupied orbital CH64) Least stable·==-- Most stable (DCSP3 (DCSP2 (DCsp PhCC-H(2 The above trend indicates that the greater the of S-character at a given atom, the greater the electronegativity of that atom S-Character2 2.5 3 3.5 4 4.5 5 Pauling Electronegativity 20 25 30 35 40 45 50 55 % S-Character CSP3 CSP2 CSP NSP3 NSP2 NSP 25 30 35 40 45 50 55 60 Pka of Carbon Acid 20 25 30 35 40 45 50 55 % S-Character CH4 (56) C6 H6 (44) PhCC-H (29) CSP3 CSP2 CSP 1 S Orbital 2 S Orbital 3 S Orbital 2 S Orbital 2 P Orbital 3 P Orbital D. A. Evans Chem 206 This becomes apparent when the radial probability functions for S and P-states are examined: The radial probability functions for the hydrogen atom S & P states are shown below. Electrons in 2S states "see" a greater effective nuclear charge than electrons in 2P states. Above observation correctly implies that the stability of nonbonding electron pairs is directly proportional to the % of S-character in the doubly occupied orbital Least stable Most stable The above trend indicates that the greater the % of S-character at a given atom, the greater the electronegativity of that atom. There is a direct relationship between %S character & hydrocarbon acidity There is a linear relationship between %S character & Pauling electronegativity Hybridization vs Electronegativity Å Radial Probability 100 % 100 % Radial Probability Å S-states have greater radial penetration due to the nodal properties of the wave function. Electrons in S-states "see" a higher nuclear charge