Lecture2Outline of Last Lecture I. Types of bondsA. Non-polar bondsB. Non-polar bondsC. Ionic bondsD. Multiple bondsII. Formal chargeIII. VSEPRIV. Resonance structuresOutline of Current Lecture CHEM 333 1st EditionI. Recognizing patterns for drawing resonance structuresThings not to do when creating resonance structuresII. s and p orbitalsIII. Electrons as wavesIV. HybridizationV. sp3 orbitalsCurrent LectureI. Recognizing patterns for drawing resonance structuresA. Lone pair next to a pi bondB. Lone pair next to a + formal chargeC. Pi bond next to a + formal chargeD. Pi bond between two atoms, especially if one of the atoms is more electronegativeE. Pi bonds that go all around a ringII. Things not to do when creating resonance structuresA. Do not break single bondsa. Example (do not do this, it is wrong because you break single bond and make two seperate molecules):b.B. Do not exceed octet:a. Example (do not do this, it is wrong because C has 5 bonds on the right):b.C. Do not move atoms:a. Example (do not do this, it is wrong because hydrogens are moved):III. s and p orbitals: electrons are found in s and p orbitals. Electrons do not have defined orbitals like planets, they have regions of space they travel in. We never know exactly where the electrons are, just a reasonable probability.A. s orbitals: electrons are most likely near the nucleusB. p orbitals: look like bow tiesIV. Electrons as wavesA. Two types of waves:a. traveling: sound, waterb. standing: guitar stringi. This is the type of wave that explains electrons.B. Wave function: math that describes thisC. Quantum mechanics: math that describes the wave function of an electron in3D spaceD. Density of electron: found by squaring the wave function, which gets the probabilty of finding the electronsE. Constructive vs. destructive waves:a. Constructive: both waves are at highest points when the two waves meetb. Destructive: one wave is at the highest point and one wave is at the lowest point when two waves meetF. When two orbitals come together to make a bond:a. Orbitals “in phase” -> add constructivelyb. Orbitals “out of phase” -> substract destructivelyc. Example: H bonding to Hd.e.V. Hybridization: atomic orbitals combine to make new orbitalsA. Tetrahedral shape: 1s + 3p -> 4sp3a. 109.5°b. 25% s characterB. Trigonal planar shape: 1s + 2p -> 4sp2 pa. 120°b. 33% s characterA. Linear shape: 1s + 1p -> 2spa. 180°b. 50% s characterVI. sp3 orbitals: 4 bonds -> 4 orbtialsA. Example:B.
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