Element of Carbon

Bonding in Carbon Variation because of half filled valence level and relatively small size. Remember the octet rule Carbon can form single, double or triple bonds. Bonds form because of hybridization. Oxygen and nitrogen can have have single or multiple bonds but also have unshared pairs of electrons.

Allotropes Same element different bonding patterns. Diamond: 3 d network. It is the hardest and most abrasive. Graphite: 2 d network. Atoms on the same plane with loosely held electrons. It is soft and slippery. Amorphous: no arrangement. Fullerenes: Buckyballs. 60 carbons with sp2 hybrid. 20 hexagonal and 12 pentagonal rings.

Hydrocarbons Consist of hydrogen and carbon only. Alkanes are hydrocarbons with only single bonds. Petroleum and coal are major sources. Saturated hydrocarbons have all single bonds. Unsaturated hydrocarbons have at least 1 double or triple bond.

Type of formulas Molecular formula: gives the number of each kind of atom in a compound. Structural formula: provides the bonding arrangement of atoms in a molecule. Isomers: compounds with same molecular formula but different structural formulas.

Types of Isomers Structural or constitutional isomers: isomers that vary in bonding attachment of atoms. Skeletal, Positional or functional are this type. Stereoisomers: isomers with same bonding attachments of atoms but different spacial orientations. Geometric and conformational are this type.

Rules for Drawing Structures Every atom in the molecular formula must be used. Valence of every atom must be satisfied. C 4 N 3 O,S 2 H,F,Cl,Br,I 1

Alkenes are compounds composed of C & H and at least 1 double bond. Alkynes are compounds composed of C & H and at least 1 triple bond. Cyclic hydrocarbons have rings. The smallest has 3 carbons. Aromatics are unsaturated cyclic compounds.

How Do You Do It? Bond together continuously with single bonds all atoms with valence greater than one. Attach monovalent atoms to the polyvalent atoms until all valances have been satisfied. If there are insufficient monovalent atoms in a molecular formula to accompany step 2, insert double or triple bonds between polyvalent atoms until it is possible to satisfy all valences.

4. To construct isomers of a molecular formula, vary the arrangement of atoms and bonds in the molecules.

Other Formulas Cycloalkanes: cyclic compounds containing only carbon and hydrogen. (CnH2n) Condensed Formula: Hydrogen for each carbon is grouped. Framework uses lines, with the intersection of the lines and end of lines are understood to be carbons unless otherwise specified. CH3 and CH2 are grouped in parentheses as appropriate.

Positional Isomers: isomers that differ in the location of a noncarbon group or double or triple bond. There is no change in the carbon skeleton.

Conformational isomer Conformational isomers: isomers that differ as a result of the degree of rotation around a carbon-carbon bond. Eclipsed: conformation around a carbon-carbon single bond in which attached atoms are as close together as possible. Staggered: conformation around a carbon-carbon single bond in which attached atoms are as far apart as possible.

Cycloalkanes-Conformational Isomers Cycloalkanes have different stability because of their bond angle. Smaller rings are less stable than the larger rings. Larger rings are not flat but puckered. If the carbons are puckered in the same direction, they form a boat configuration.

If the carbons are not in the same plane, they form a chair configuration. This is the most stable conformation. Axial bonds are bonds on a cyclohexane chair perpendicular to the ring with three up and three down on altering carbons Equatorial bonds on a cyclohexane chair parallel to the ring.

Geometric Isomers in Cyclic Compounds There is no free rotation in a cyclic compound. Because of this, cycloalkanes can be thought of a having sides. Cis isomer is a geometric isomer in groups are on the same side of ring or double bond. Trans isomer is a geometric isomer in which groups are on opposite sides of ring or double bond.