Lewis Dot Structures Dr.Gergens - SD Mesa College

1. Supplemental packet page 66 Lewis Dot StructuresDr.Gergens - SD Mesa College

2. 3. N O , these elements may have a variable number of bonds (2) (1) (4) (3) Things to keep in mind when drawing Lewis structure 1. Always count valence electrons C N O F H 2. Know the preferred number of bonds to these elements 4 3 2 1 1 4. If the substance has hydrogen list first in its formula: a. the substance is characterized as an acid b. the H is bound to oxygen in the substance’s structure 5. F O N Cl Br I S C H for determining bond polarity

3. Large difference in electronegativity between H—F most polar bond between C—F very polar bond Little difference in electronegativity Less polar F O N Cl Br I S C H for determining bond polarity between nonmetal atoms F O N Cl Br I S C H Between identical atoms, C-C, F-F bonding is nonpolar

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9. valence shell electron pair repulsion 109.5 109.5 109.5 109.5 120 120 120 120 120 120 120 120 109.5 109.5 109.5 109.5 tetrahedral trigonal planar linear linear 107.5 107.5 q<120 pyramidal or trigonal pyramid bent 104.5 bent Ideal bonding for carbon is Four bonds to carbon - Four bonding modes 180 180 Ideal bonding angles for carbon Bond angles for non-ideal geometries are less than an ideal angle in ideal for C. This is because an electron pair 1) occupies a lot of space & 2) is held close to nucleus of central atom

10. supplemental HO 70

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