CHEM 333 Lecture Notes - Lecture 2: Trigonal Planar Molecular Geometry, Molecular Geometry, Formal Charge
15 Sep 2016
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Covalent bonds= sharing electrons between atoms to fill valence shell o o. Also need to worry about nonbonding electrons: o. Lone pairs: on o,n,cl,f,br,i,s, don"t make bonds to these. # of bonds vs. lone pairs (neutral) Some electrons are shared equally in bonds o. But some elements don"t share electrons equally (when 2 diff elements) o o. This side means partial positive --l----> this side means partial negative. Remember electronegativity trend: increases from left to right; decreases when going down periodic table. Fully transfer electrons to get ion pairs. Remove 1 electron from valence shell of lower electronegative atom and give to more electronegative atom o. Formal charge= # valence shell electrons - # electrons in lone pairs - # shared bonds. Bond angles --> vsepr: valence shell electron pair repulsion. Electrons want to be as far away from each other as possible. Need to know how many regions of density you have o.
