Rules for naming hydrocarbons: alkanes to arenes | 16-18 years

In this activity, students assemble the names of hydrocarbon structures using component parts written on cards. By discussing the rules for naming hydrocarbons including alkanes, alkenes, alkynes and arenes, students check and clarify their understanding.

This activity is best used after students have spent some time on this topic.

Learning objectives

Students will:

• Understand and be able to use the rules for naming hydrocarbons including alkanes, alkenes, alkynes and arenes.

Sequence of activities

Introductory activity

1. Divide students into groups of three.
2. Provide each group with a molecular model kit made up of four carbon atoms, 10 hydrogen atoms and 10 bonds of which four need to be ‘flexible’ bonds.
3. Ask them to construct as many different molecules as possible using all or some of the component atoms and bonds.
4. Invite groups to show and to name some of their molecules.
5. Now share the learning objectives with the students.

Naming hydrocarbons: stage 1

Give each student a ’Student sheet’, and distribute to each group:

• A set of ‘Hydrocarbon naming cards’
• ‘Hydrocarbon structure cards’ from sheet 1, or ’Hydrocarbon structure cards’ from sheets 1 and 2.

Circulate and support groups as they:

1. Shuffle the ‘Hydrocarbon structure cards’.
2. Take turns in choosing a ‘Hydrocarbon structure card’ and use the ’Hydrocarbon naming cards’ to construct the appropriate name.
3. Discuss and agree a name, where a student is unsure.
4. Write the name of the hydrocarbon on their ’Student sheet’.
5. Ask for a ’Names of structures answer sheet’, when they have named all the hydrocarbons.
6. Compare the answers with their group answers and modify their own where necessary.

Naming hydrocarbons: stage 2

Ask students, in their groups, to:

1. Identify and make a note of any types of structures that they all found difficult to name correctly.
2. Assesses what type of structures each other student was able to name with confidence and what structures caused difficulty.
3. Write these assessments on the ‘Student sheet’.

Commentary

Introducing the learning objectives follows naturally from the initial task of constructing molecular models.

The group work, using cards, involves the students in peer assessment, which is formalised at the end of the session. Comparing their ideas with an answer grid helps students to recognise the standard they are aiming for.

The activity also includes an element of self assessment, both during the naming stage and formalised at the end of the sequence.

Equipment

• Molecular model kits, one for each group of three students, containing:
  • Carbon atoms, x4
  • Hydrogen atoms, x10
  • Bonds, x10 (including four flexible bonds)