The properties of the alkenes

Question 1

What type of hydrocarbons are alkenes?

Answer 1

Unsaturated

Question 2

Why are alkenes unsaturated hydrocarbons?

Answer 2

They contain at least one carbon to carbon double bond in their structure

Question 3

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

Answer 3

CnH2n

Question 4

What are the three other possible structures of alkenes?

Answer 4

1) Branched
2) Contain more than one double bond
3) Cyclic

Question 5

How many electrons does carbon have in its outer shell?

Answer 5

Four

Question 6

What type of bonds do three of the four electrons in each carbon atom of the double bond make?

Answer 6

Sigma bonds to the other carbon atom of the double bond and two electrons to two other atoms (carbon or hydrogen)

Question 7

Where is the fourth electron of a carbon?

Answer 7

In a p-orbital

Question 8

What type of bond does the last electron of a carbon make?

Answer 8

Pi bond

Question 9

How is a pi bond formed?

Answer 9

By the sideways overlap of two p-orbitals, one from each electron pair in the pi bond

Question 10

Where is the pi electron density concentrated?

Answer 10

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

Question 11

What does the pi bond do to the two carbon atoms?

Answer 11

Locks them in position and prevents them from rotating around the double bond

Question 12

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

Answer 12

Trigonal planar

Question 13

What are the three reasons for the trigonal planar shape of the bond?

Answer 13

1) Three regions of electron density around each carbon atom
2) Three regions repel each other as far apart as possible
3) All atoms are in the same plane

Question 14

What are the bond angles in a double bond?

Answer 14

120 o