1. Unsaturated Hydrocarbons

2. Alkenes - hydrocarbons with carbon- carbon double bonds
Alkynes - hydrocarbons with carbon- carbon triple bonds

3. Alkenes Alkenes - one carbon-carbon double bond
Alkadienes – two carbon-carbon double bonds
Alkatrienes – three carbon-carbon double bonds

4. Nomenclature of Alkenes
1. Find the longest continuous chain of carbon atoms that contains the double bonds and name it using the ending –ene, -diene or –triene.
2. Number the chain so that the double bond has the lowest possible number.
3. Name, number and alphabetize the constituent groups

5. 4. If cis-trans isomers exist, place the correct term in front of the number of the bond to which it applies.
Cis- same side
Trans – opposite side
NOTE: Double bonds in rings usually exist in the cis form. (Larger rings of eight or more carbons can accommodate the trans form)

6. Nomenclature examples1. 2. 3.

7. 4. 5. 6.

8. Some common names Ethene  ethylene Propene  propylene
Vinyl group (derived from
ethylene)
Allyl group (derived from
propylene)

9. Orbital Model of a Double Bond
In a double bond, carbon can only combine with 3 other atoms. Orbitals are arranged like an equilateral triangle. The bond angle is 120° TRIGONAL
Carbon-carbon double bonds have restricted rotation.
Geometric isomers occur when the groups attached to each carbon are different from each other.

10. Name each of the following and indicate if they are geometric isomers or not.