Alkenes: Structure, Bonding & Reactivity

Question 1

Are alkenes saturated or unsaturated hydrocarbons?

Answer 1

• Alkenes are unsaturated hydrocarbons

- Unsaturated means they have at least one C=C bond

Question 2

Describe the bonding in alkenes

Answer 2

• Bonding in alkenes involves a double covalent bond, a centre of high electron density
• Also involves π bond

Question 3

Why is there no rotation about the C=C double

bond?

Answer 3

• Due to the π (pi) orbital
• Pi bonds are formed from overlapping p orbitals
• Electron density above and below the single bonds attached to C=C, which holds the carbon atoms in place

Question 4

What is the general formula of alkenes?

Answer 4

• CnH2n