【正文】 Bonding amp。 Shapes of Molecules Schematic View of an AtomA small dense nucleus, diameter 1014 ~1015m, which contains positively charged protons and most of the mass of the atom.An extranuclear space, diameter 1010 m, which contains negatively charged electrons. Electron Configuration of AtomsElectrons are confined to regions of space called principle energy levels (shells) . Each shell can hold 2n2 electrons (n = 1,2,3,4......) Electron Configuration of AtomsShells are divided into subshells called orbitals, which are designated by the letters s, p, d, f,........s (one per shell) p (set of three per shell 2 and higher) d (set of five per shell 3 and higher) .....Aufbau Principle: Orbitals fill in order of increasing energy from lowest energy to highest energy.Pauli Exclusion Principle: Only two electrons can occupy an orbital and their spins must be paired.Hund’s Rule: When orbitals of equal energy are available but there are not enough electrons to fill all of them, one electron is added to each orbital before a second electron is added to any one of them. Lewis Dot StructuresGilbert N. LewisValence shell: the outermost occupied electron shell of an atomValence electrons: electrons in the valence shell of an atom。 the position of all nuclei must be the same4. have the same number of paired and unpaired electronsfilled valence shellsstructures in which all atoms have filled valence shells contribute more than those with one or more unfilled valence shellsstructures that carry a negative charge on the more electronegative atom contribute more than those with the negative charge on the less electronegative atom Molecular Orbital TheorySigma 1s bonding and antibonding MOsMO energy diagram for H2: (a) ground state and (b) lowest excited statepi bonding and antibonding MOs Hybrid OrbitalsHybridization of orbitals (L. Pauling)the bination of two or more atomic orbitals forms a new set of atomic orbitals, called hybrid orbitalsWe deal with three types of hybrid orbitalssp3 (one s orbital + three p orbitals)sp2 (one s orbital + two p orbitals)sp (one s orbital + one p orbital)Overlap of hybrid orbitals can form two types of bonds depending on the geometry of overlaps bonds are formed by “direct” overlapp bonds are formed by “parallel” overlapeach sp3 hybrid orbital has two lobes of unequal sizethe sign of the wave function is positive in one lobe, negative in the other, and zero at the nucleusthe four sp3 hybrid orbitals are directed toward the corners of a regular tetrahedron at angles of 176。 H: a hydrogen bonded to a 1176。 carbonTertiary (3176。carbonQuaternary (4176。torsional strain: there are 6 sets of eclipsed hydrogen interactionsstrain energy is about 116 kJ ( kcal)/mol Cyclobutanepuckering from planar cyclobutane reduces torsional strain but increases angle strainthe conformation of minimum energy is a puckered “butterfly” conformationstrain energy is about 110 kJ ( kcal)/mol Cyclopentanepuckering from planar cyclopentane reduces torsional strain, but increases angle stainthe conformation of minimum energy is a puckered “envelope” conformationstrain energy is about 42 kJ ( kcal)/mol CyclohexaneChair conformation: the most stable puckered conformation of a cyclohexane ringall bond CCC bond angles are 176。 that is, to rotate one carbon by 90176。 a reaction in which heat is releasedendothermic reaction: a reaction in which the enthalpy of the products is higher than that of the reactants。 the position of equilibrium for an exergonic reaction favors productsendergonic reaction: a reaction in which the Gibbs free energy of the products is higher than that of the reactants。CThe reason of the relative rates of radical formation:By paring the values for the sum of the two propagating steps for the monohalogenation of methane, we can understand why alkanes undergo chlorination and bromination but not iodination and why fluorination is too violent a reaction to be useful.Chapter 3 Alkene Structure and nomenclatureSaturated hydrocarbons:. alkanes contain the maximum number of carbon–hydrogen bonds possible—that is, they are saturated with hydrogen.Unsaturated hydrocarbon: contains one or more carboncarbon double or triple bondsAlkene: contains a carboncarbon double bond and has the general formula CnH2n.Degree of unsaturation (or Index of hydrogen deficiency) :. The total number of πbonds and rings in an alkene is called its degree of unsaturation.Notes:the molecular formula of the reference hydrocarbon is CnH2n+2for each atom of a Group 7 element (F, Cl, Br, I), add one Hno correction is necessary for the addition of atoms of Group 6 elements (O,S) to the reference hydrocarbonfor each atom of a Group 5 element (N, P), subtract one hydrogenA double bond consists of one sigma bond formed by the overlap of sp2 hybrid orbitals and one pi bond formed by the overlap of parallel 2p orbitalsthe two carbon atoms of a double bond and the four atoms bonded to them lie in a plane, with bond angles of approximately 120176。 given the symbol R1. Determine the number of carbons in the longest continuous carbon chain. This chain is called the parent hydrocarbon.2. The name of any alkyl substituent that hangs off the parent hydrocarbon is cited before the name of the parent hydrocarbon, together with a number to designate the carbon to which the alkyl substituent is attached.3. If more than one substituent is attached to the parent hydrocarbon, the chain is numbered in the direction that will result in the lowest possible number in the name of the pound.4. When both directions lead to the same lowest number for one of the substituents, the direction is chosen that gives the lowest possible num