New
New
Year 11
OCR
Foundation

Alkenes

I can describe and explain the reactions and properties of the first four alkenes.

New
New
Year 11
OCR
Foundation

Alkenes

I can describe and explain the reactions and properties of the first four alkenes.

Lesson details

Key learning points

  1. Reactions of an alkene happen at its functional group, C=C.
  2. Reactions of an alkene change it from an unsaturated to a saturated molecule.
  3. Larger alkenes have higher boiling points and are less flammable.
  4. Alkenes tend to burn with smoky flames due to incomplete combustion.
  5. Isomers are structures with the same molecular formula, but different arrangement of atoms in space.

Common misconception

The shortest alkene is one containing only one carbon atom.

Teach that alkenes contain the C=C bond and therefore the shortest alkene is ethene.

Keywords

  • Functional group - The functional group is the atom or group of atoms responsible for the way a compound reacts.

  • Unsaturated - Unsaturated compounds contain at least one carbon-carbon double covalent bond.

  • Saturated - Alkanes are saturated hydrocarbons as they contain only single bonds between carbon and hydrogen atoms.

  • Isomers - Isomers are structures with the same molecular formula, but different arrangement of atoms in space.

  • Alkenes - Alkenes are unsaturated hydrocarbons that contain the C=C functional group.

Use molymods to model how the double bond opens up to allow atoms to attach forming saturated compounds.
Teacher tip

Equipment

Molymods (optional to use).

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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6 Questions

Q1.
How many covalent bonds can a carbon atom form?
one
two
three
Correct answer: four
five
Q2.
What are compounds that contain hydrogen and carbon atoms only called?
Correct Answer: hydrocarbons
Q3.
Which of the following equations for the complete combustion of alkanes is correct?
alkane + oxygen → carbon monoxide + water
Correct answer: alkane + oxygen → carbon dioxide + water
alkane + water → carbon + oxygen
alkane + oxygen → carbon dioxide + hydrogen
alkane + oxygen → carbon monoxide + hydrogen
Q4.
Which of the following are possible products from the incomplete combustion of propene?
Correct answer: carbon (soot)
Correct answer: carbon monoxide
oxygen
ethene
Correct answer: water
Q5.
Which of the following is the general formula for alkanes? Use the image shown of an ethane molecule to help you work it out.
An image in a quiz
CₙH₂ₙ
CₙH₂ₙ₊₁
Correct answer: CₙH₂ₙ₊₂
CₙH₂ₙ₊₃
Q6.
Sort the following alkenes into order of increasing chain length, starting with the molecule that has the shortest chain.
1 - ethene
2 - propene
3 - butene
4 - pentene
5 - hexene

6 Questions

Q1.
Reactions of alkenes happen at their functional group. Which of the following is the functional group of alkenes?
OH
CH
C=O
Correct answer: C=C
Q2.
Match the following key terms to their definitions.
Correct Answer:unsaturated compounds,compounds that contain at least one carbon–carbon double covalent bond

compounds that contain at least one carbon–carbon double covalent bond

Correct Answer:saturated compounds,compounds that contain only single covalent bonds

compounds that contain only single covalent bonds

Correct Answer:alkenes,hydrocarbons that contain the C=C functional group

hydrocarbons that contain the C=C functional group

Correct Answer:functional group,the atom or group of atoms responsible for the way a compound reacts

the atom or group of atoms responsible for the way a compound reacts

Q3.
Which of the following statements about alkenes are correct?
Longer alkenes have lower boiling points than shorter alkenes.
Correct answer: Longer alkenes have higher boiling points than shorter alkenes.
Correct answer: Larger alkenes are less flammable than shorter alkenes.
Longer alkenes are more flammable than shorter alkenes.
Q4.
What is the name for structures with the same molecular formula but different arrangements of atoms in space?
Correct Answer: isomers
Q5.
Which two of the following reactants are needed to produce the product shown in the image?
An image in a quiz
propene and bromine
Correct answer: ethene and bromine
propene and chlorine
ethene and chlorine
Q6.
Which of the following is the organic product when propene reacts with steam at a high temperature and pressure, in the presence of an acid catalyst?
propane
Correct answer: propanol
propene
propanoic acid
propyl propanoate