13.1 Properties Of The Alkenes

Question 1

What type of hydrocarbons are alkenes?

Answer 1

Unsaturated

Question 2

What is the key feature of alkenes?

Answer 2

They contain at least one C=C bond.

Question 3

What is the general formula for aliphatic alkenes that contain one double bond?

Answer 3

Cn H2n

Question 4

What happens to the electrons in each carbon atom of the double bond?

Answer 4

-3 of the four electrons are used in 3 sigma bonds, one to the other carbon atom of the double bond, and the 2 other electrons to two other atoms
-This leaves one electron not involved in sigma bonds

Question 5

What is a Pi bond formed by?

Answer 5

-The sideways overlap of two p-orbitals, one from each carbon atom of the double bond.

Question 6

Where is the electron density concentrated in a Pi-bond?

Answer 6

Above and below the line joining the nuclei of the bonding atoms

Question 7

What does the Pi bond do to the 2 carbon atoms in the double bond?

Answer 7

Locks the two carbon atoms in position, and prevents them from rotating around the double bond.

Question 8

How do Pi bonds separate alkenes from alkenes?

Answer 8

-The Pi bonds between two carbons lock them into position, and prevents them from rotating around the double bond.
-This makes rotation around every atom impossible, and is what separates alkenes from alkanes.

Question 9

What is the shape around each of the carbon atoms in the double bond?

Answer 9

Trigonal planar.