CHEM 14A Midterm: SE 2 Review
21 Nov 2016
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Document Summary
Delocalization means that a shared electron pair is distributd over several pairs of atoms and cannot be identified with just one pair of atoms. Resonance structure must satisfy all usual requirements, can only happen if there are multiple bonds, and the nuclei are in the same positions. Formal charge = valence electrions - (non-bonded elections + number of bonds) C,n,o,f obey the octet rule rigorously, while atoms in group 3 and higher don"t always. The higher the dissocation energy d the stronger the bond - high energy vibrational motion leads to bond breakage. Multiple bonds are shorter in homogenous molecules because the bonding electrons draw the nuclei closer. Homonuclear atoms are almost always purely covalent, heteronuclear are almost all ionic. An electric dipole is formed between two homonuclear atoms, a partial positive charge is equal to a partial negative charge. Electronegativity is the power of an atom to pull an electron when it is part of a moleculte.
