Chembio lec

• Carbon forms covalent bonds in all its elemental forms and compounds. – The ground state electron configuration of C is [He]2s 2 2p 2 ; the formation of carbon ions is therefore energetically unfavorable. – C has an electronegativity of 2.5, which is midway between that of most metals and nonmetals. C prefers to share electrons.
• Carbon exhibits catenation, the ability to bond to itself and form stable chain, ring, and branched compounds. – The small size of the C atom allows it to form short, strong bonds. – The tetrahedral shape of the C atom allows catenation.
• As atomic size increases down the group, bonds between identical atoms become longer and weaker. – A C–C bond is much stronger than a Si–Si bond.
• The bond energies of a C–C bond, a C–O bond, and a C–Cl bond are very similar. – C compounds can undergo a variety of reactions and remain stable, while Si compounds cannot.
• Si has low energy d orbitals available for reaction, allowing Si compounds to be more reactive than C compounds
• Many organic compounds contain heteroatoms, atoms other than C and H. – The most common of these are O, N, and the halogens
• Most reactions involve the interaction of electron rich area in one molecule with an electron poor site in another. – C–C bonds and C–H bonds tend to be unreactive. – Bonds between C and a heteroatom are usually polar, creating an imbalance in electron density and providing a site for reactions to occur.
• Each C atom can form a maximum of 4 bonds. Groups joined by a single bond can rotate, so there are often several different arrangements of a given carbon skeleton that are equivalent:
• Each C atom can form a maximum of four bonds. These may be four single bonds, OR one double and two single bonds, OR one triple and one single bond.
• The arrangement of C atoms determines the skeleton, so a straight chain and a bent chain represent the same skeleton.
• Groups joined by a single bond can rotate freely, so a branch pointing down is the same as one point up.
• A C atom single-bonded to one other atom gets three H atoms. A C atom single-bonded to two other atoms gets two H atoms.
• A C atom single-bonded to three other atoms gets one H atom. A C atom single-bonded to four other atoms is already fully bonded (no H atoms).
• A double-bonded C atom is treated as if it were bonded to two other atoms. A double- and single-bonded C atom or a triple-bonded C atom is treated as if it were bonded to three other atoms
• Hydrocarbons contain only C and H. Alkanes are hydrocarbons that contain only single bonds and are referred to as saturated hydrocarbons. The general formula for an alkane is C n H2n+2, where n is any positive integer. Alkanes comprise a homologous series, a group of compounds in which each member differs from the next by a –CH2 – group.
• The name of any organic compound is comprised of three portions: PREFIX + ROOT + SUFFIX
• The root name of the compound is determined from the number of C atoms in the longest continuous chain.
• The suffix indicates the type of organic compound, and is placed after the root. The suffix for an alkane is –ane.
• The prefix identifies any groups attached to the main chain.
• Roots Number of C Atoms meth- 1 eth- 2 prop- 3 but- 4 pent- 5 hex- 6 hept- 7 oct- 8 non- 9 dec- 10
• Nomenclature naming for compounds

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• different kind of formulas of alkane

  
• Different types of cycloalkanes

  
• more cycloalkanes

  
• Constitutional or structural isomers have the same molecular formula but a different arrangement of the bonded atoms. A straight-chain alkane may have many branched structural isomers. Structural isomers are different compounds and have different properties. If the isomers contain the same functional groups, their properties will still be similar.
• The Constitutional Isomers of C4H10 and C5H12

  
• Formulas, molar masses (in g/mol), structures, and boiling points (at 1 atm pressure) of the first 10 unbranched alkanes.

  
• Alkanes are nonpolar and their physical properties are determined by the dispersion forces between their molecules.
• Stereoisomers are molecules with the same arrangement of atoms but different orientations of groups in space. Optical isomers are mirror images of each other that cannot be superimposed. A molecule must be asymmetric in order to exist as a pair of optical isomers. An asymmetric molecule is termed chiral. Typically, a carbon atom is a chiral center if it is bonded to four different groups
• If two compounds are mirror images of each other that cannot be superimposed, they are called optical isomers.
• Two chiral molecules. optical isomers of 3-methylhexane optical isomers of alanine