Alkenes At least one double bond present in the main chain General formula is CnH2n Form a trigonal planar shape Note: more on shapes in the next unit Create a 120° angle between bonds Considered “unsaturated” because other hydrogen atoms can be added Always end in “~ene”

Nomenclature Identify and name the longest carbon chain that CONTAINS THE DOUBLE BOND(S). Number the carbons in the chain so that the two carbons involved in the double bond have the lowest possible numbers. If the double bond is equidistant from both ends, number the chain so that the substituent(s) have the lowest possibly number. Follow same rules for identifying and naming prefixes.

Nomenclature Try naming this… 2-ethyl 1-pentene

Nomenclature Now let’s draw 1-butene and 2-butene… 1-butene 2-butene

Nomenclature Let’s try a structure with more than one double bond… 1,3-pentadiene

Nomenclature Let’s put everything together and name… 4-ethyl-3,6-dimethyl 1,2,4-octatriene

Diastereomers Consider the following compounds… cis-2-butene trans-2-butene 2-methyl- 1-propene

Alkynes At least one triple bond present in the main chain General formula is CnH2n-2 Form a linear shape Note: more on shapes in the next unit Create a 180° angle between bonds Considered “unsaturated” because other hydrogen atoms can be added Always end in “~yne”

Nomenclature Identify and name the longest carbon chain that CONTAINS THE TRIPLE BOND(S). Number the carbons in the chain so that the two carbons involved in the triple bond have the lowest possible numbers. If the triple bond is equidistant from both ends, number the chain so that the substituent(s) have the lowest possibly number. Follow same rules for identifying and naming prefixes.

Nomenclature Try naming this… 3,4-dimethyl 1-hexyne

Nomenclature Now let’s draw 1-butyne and 2-butyne… 1-butyne 2-butene

Nomenclature Let’s try a structure with more than one triple bond… 2,4-hexadiyne

Nomenclature Let’s put everything together and name… 4-ethyl-4,5-dimethyl 2,6-octadiyne