Billy: Why did you say alkanes two times?
Me: No, I said alkenes and alkynes.
Billy: You just did it again.
Me: No I di- nevermind let me explain
Alkenes are is the simplest of the unsaturated hydrocarbons, hydrocarbons which will react with hydrogen. They contain one or more double bonds between carbon atoms. They are indicated by the symbol =. The presence of a double bond is indicated when the ending changes from -ane to -ene. The formula for alkenes is CnH2n.
| Alkenes | |
|---|---|
| Ethene | C2H4 |
| Propene | C3H6 |
| Butene | C4H8 |
| Pentene | C5H10 |
Alkynes are hydrocarbons which contain a triple carbon bond. They are indicated by a symbol of 3 lines. The presence of a triple bond is indicated when the ending changes from -ane to -yne. The formula for alkynes is CnH2n-2.
| Alkynes | |
|---|---|
| Ethyne | C2H2 |
| Propyne | C3H4 |
| Butyne | C4H6 |
| Pentyne | C5H8 |
Trans and Cis
Are these two molecules the same? No they are not because no matter how you rotate the molecule, you do not end up with the same molecule. One of these is cis and one of these is trans. Which one is which? The one on the LEFT is trans, because the methyl groups are on the opposite ends. The one on the right is a cis, because the methyl- groups are located on the same side. The molecule on the left is called trans-2-butene, while the right one is called cis-2-butene.
*note* this only applies to alkenes
Ohhhh yeah 2 weeks left. Enjoy the vid.
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