Organic Chemistry - Hydrocarbons: Alkenes

Question 1

alkenes

Answer 1

• hydrocarbons with at least one double bond, can be straight chain, branched, or in a ring (cyclic)
• unsaturated hydrocarbon because carbons are involved in double bond are only connected to three other atoms

Question 2

nomenclature of alkenes

Answer 2

1. find the longest chain of carbon atoms that contains the double bond to establish the parent name. add -ene to root name
2. number the chain so that the carbons of the double bond are given the lowest numbers possible

Question 3

naming alkenes

Answer 3

C Root #C Root

1. NONE 6. - Hex-
2. Eth- 7. - Hept-
3. Prop- 8. - Oct-
4. But- 9. - Non-
5. Pent - 10. - Dec-

Question 4

2-butene

Answer 4

CH3CH = CHCH3

Question 5

2,4-dimethyl-1-pentene

Answer 5

CH2=CCH2CHCH3
| |
CH3 CH3

Question 6

nomenclature for cycloalkenes

Answer 6

1. count number of carbon atoms in ring and add prefix cyclo- to parent alkene name
2. the ring is numbered to give the double bond the lowest possible numbers (in the case of a cycloalkene this is always the numbers 1 and 2)

Question 7

bonding in alkenes

Answer 7

• it has combined na s orbital with two p orbitals to make three sp^2 orbitals, but still has the remaining p orbital
• the side to side overlap of the two p orbitals is referred to as a pi bond
• therefore a double bond has both a pi bond and a sigma bond

Question 8

a double bond contains ______

Answer 8

• one sima and one pi bond

Question 9

the bond angles around a carbon in a double bond are ____ and it is _____ hybridized

Answer 9

• 120, sp^2