CHEM 2301 1st Edition Lecture 3Outline of Last Lecture I. Shorthand line drawingsII. Bond polarity and electronegativityIII. Basic principles of resonance theoryIV. Assessing the relative importance of resonance structuresOutline of Current Lecture V. Bonding in organic moleculesI. HybridizationVI. Drawing hybridization structuresCurrent Lecture- Bonding in organic moleculeso Charge on a hetero atom (non-carbon) does not contribute to a significant resonance structure if it is positive. Negative charges are significant Change only one bond per resonance structureo Methane (CH4) contains four bonds that are 109.5o apart and are equal length o Sp3 hybridization occurs in molecules with a tetrahedral geometry  Hybridization shape: dumbbell that is much bigger on the side that is bonded to another atomo Sp2 hybridization means a trigonal planar geometry with bond angles of 120oo To determine hybridization, only count the number of atoms that are bonded to the central atom, not the overall number of bonds.  An atom bonded to four groups is sp3 hybridized; an atom bonded to three groups is sp2 hybridized; an atom bonded to two groups is sp hybridized Hybridization occurs in atoms when the s and p electron orbitals combine so that the atom can form more bonds and more easily become stable. This is why carbon likes to form four bonds even though it only has two electrons in its “p” orbital.o To show bond angles when drawing molecules: Wedges indicate that the atom or group is in front of the plane Dashed lines indicate that the atom or group is behind the planeThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Drawing hybridization structureso Single bonds are known as sigma bonds and are drawn as a half-dumbbell shape.o Double bonds are known as pi bonds and are drawn as a complete dumbbell thatgoes vertically through the two atoms that are involved in the double bond and are bonded in the space between the two of them. In molecules that involve a double bond, one sigma bond and one pi bond make up the double bond. This should be drawn as one sigma bondbetween the atoms and one pi bond through them.  Pi bonds are weaker than sigma bondso Example structure: