CH 221 1st Edition Lecture 3Outline of Last Lecture I. Structure of an Atoma. ElectronsII. Isotopes of CarbonIII. Carbon OrbitalsIV. Distribution of ElectronsV. Orbital RulesVI. Carbon, Nitrogen, and Oxygen Distributiona. Octet Ruleb. HydrogenVII.BondingOutline of Current LectureVIII. Lone Pairsa. Methaneb. Neutral Nitrogenc. OxygenIX. Bonds and Orbitalsa. Carbonb. Methanec. Ethaned. EtheneCurrent LectureVIII. Lone PairsThe number of bonds plus the number of lone pairs must equal 4. Halogens have 3 lone pairs, oxygen has 2 lone pairs, and nitrogen has 1 lone pair. Neutral carbons form four bonds such as in Methane which contains 1 carbon atom single bonded to 4 hydrogen atoms. Another example is ethane which contains two carbon atoms single bonded to each other as well as three hydrogen atoms respectively. If carbon does not form four bonds, it becomes charged (ex. methylcation which is a carbocation or methyl anion which is a carbion).Formal Charge is calculate by:- The number of valence electrons – ½ the number of bonding electronsThese 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.OR- The number of valence electrons – the number of bondsa. Neutral Nitrogen forms three bonds and has one lone pair. Examples include ammonia and hydrazine. If this is not the case the nitrogen compound is charged (the ammonium ion).b. Oxygen has two bonds and two lone pairs, like in water. If this is not the case, oxygen forms compounds such as the hydronium ion and the hydroxide ion. The steps to drawing Lewis structures for these compounds are:1. Count total number of electrons2. Draw individual atoms including their valence electrons3. Pair atoms around carbon chainIX. Bonds and OrbitalsSigma bonds are very strong therefore require a huge amount of energy to be broken (dissociated). Approximately 104 Kcal/mol. Atomic orbitals combine to form molecular orbitals which lowers the electrons’ energy level which makes the electrons happy. a. Carbon must promote an electron in order to have four bonds meaning one electron from the 1s energy level jumps to the unfilled 2p energy level. Four orbitals are mixed to form 4 hybrid orbitals, sp3 orbitals have a large lobe and a small lobe.b. The carbon in methane is sp3which gives methane its tetrahedral shape and 109.5º angle. Also, all the C-H bonds in methane are identical making it nonpolar. c. The C-C bonding in ethane is formed by sp3- sp3 overlap and the C-H bonding is formed by sp3−s overlap.d. In ethane, three orbitals are hybridized meaning three hybrid orbitals form sp2.Sigma and Pi bonds help form the bonds between carbons and
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