Class: Senior Secondary School 1 (SS1, SS 1, SSS1, SSS 1)
Term: 3rd Term
Week: 8
Age: 15 years
Duration: 45 minutes
Subject: Chemistry
Curriculum Theme: Chemistry
Previous Lesson: Carbon And Its Compounds: Crude Oil Fractions, Natural Gas and Importance.
Topic: Hydrocarbons
Subject Matter: Structure and valency of carbon, meaning and examples of hydrocarbons, homologous series characteristics and IUPAC naming, and saturated hydrocarbons composition and structure

Specific Objectives

By the end of the lesson, pupils should be able to:

Cognitive Domain:

state the valency of carbon and explain what tetravalency means.
define hydrocarbons and give examples of alkanes, alkenes, and alkynes.
define a homologous series and list its characteristics.
apply basic IUPAC rules to name simple hydrocarbons (C1–C10) and write their formulae.
state the general formula and basic structural features of saturated hydrocarbons (alkanes).

Affective Domain:

show interest in using correct names and structures when writing hydrocarbons.
demonstrate safety awareness when handling bromine water and silver trioxonitrate(V) solution.

Psychomotor Domain:

build simple carbon chain models using beads/model kits.
draw displayed/structural formulae of simple saturated hydrocarbons (methane to butane).
use a chart to identify a homologous series member and write its name and structure correctly.

work cooperatively in groups to build and name hydrocarbon models.
participate in group correction and accept feedback politely.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum (NERDC).
State Unified Scheme of Work.
Ababio, O. Y. New School Chemistry for Senior Secondary Schools.
OpenStax Chemistry 2e: Organic Chemistry (introduction and hydrocarbons).
IUPAC: Chemical Nomenclature (overview and naming principles).
Khan Academy: Alkanes and basic naming.

Instructional Materials

The teacher will teach this lesson with the aid of:

Hydrocarbon model kits or coloured beads and sticks/wire (to represent atoms and bonds).
Charts showing homologous series and IUPAC prefixes (meth-, eth-, prop-, but-, pent-, hex-, hept-, oct-, non-, dec-).
Bromine water (for showing test for unsaturation, handled with care).
Silver trioxonitrate(V) solution (used as ammoniacal silver nitrate for testing terminal alkynes, teacher-handled).
Test tubes, droppers, and a test-tube rack.
Whiteboard/marker or chalkboard/chalk.

Rationale for the Lesson

Hydrocarbons are common in fuels, plastics, and many household products. Understanding carbon bonding, homologous series, and correct naming helps pupils to write structures correctly and answer organic chemistry questions in class tests and examinations.

Prerequisite/Previous Knowledge

Pupils can identify elements and valency, understand the idea of bonding, and can write simple chemical formulae.

Lesson Content/Board Summary

HYDROCARBONS

Structure and Valency of Carbon

Carbon is tetravalent, meaning one carbon atom forms four covalent bonds. Carbon also shows catenation, meaning it can bond to itself to form chains and rings.

The following are common ways carbon bonds in organic compounds:

Single bond (C–C) in alkanes.
Double bond (C=C) in alkenes.
Triple bond (C≡C) in alkynes.

Meaning and Examples of Hydrocarbons

Hydrocarbons are organic compounds that contain only carbon and hydrogen.

The following are examples of hydrocarbons:

Alkanes: methane (CH₄), ethane (C₂H₆), propane (C₃H₈).
Alkenes: ethene (C₂H₄), propene (C₃H₆).
Alkynes: ethyne (C₂H₂), propyne (C₃H₄).

Homologous Series

A homologous series is a family of organic compounds with the same functional group and a general formula, where successive members differ by a CH₂ unit.

The following are characteristics of a homologous series:

Same general formula.
Successive members differ by CH₂.
Similar chemical properties.
Gradual change in physical properties (e.g., boiling point increases as molecular size increases).
Prepared by similar methods.

Basic IUPAC Naming of Hydrocarbons

IUPAC naming uses a prefix to show the number of carbon atoms and a suffix to show the type of hydrocarbon.

The following are common prefixes for carbon chain length:

1: meth-
2: eth-
3: prop-
4: but-
5: pent-
6: hex-
7: hept-
8: oct-
9: non-
10: dec-

The following are common suffixes for hydrocarbons:

-ane for alkanes (single bond).
-ene for alkenes (double bond).
-yne for alkynes (triple bond).

The following are simple IUPAC naming rules for straight-chain hydrocarbons:

Count the number of carbon atoms in the longest continuous chain.
Choose the correct prefix for the number of carbon atoms.
Choose the correct suffix (-ane, -ene, -yne) based on the type of bond.
For alkenes and alkynes, indicate the position number of the double or triple bond (for longer chains).

Saturated Hydrocarbons (Alkanes): Composition and Structure

Saturated hydrocarbons are alkanes with only single bonds between carbon atoms. They contain the maximum number of hydrogen atoms.

The following are key points about alkanes:

General formula: C_nH_2n+2.
Carbon atoms are linked by single covalent bonds (C–C).
Each carbon completes four bonds.
Examples: methane (CH₄), ethane (C₂H₆), propane (C₃H₈), butane (C₄H₁₀).

Simple Tests Linked to Unsaturation (Teacher Demonstration)

Some tests help to identify unsaturated hydrocarbons during practical work.

The following are simple test observations:

Bromine water: alkenes and alkynes decolourise bromine water; alkanes do not decolourise bromine water under normal conditions.
Ammoniacal silver trioxonitrate(V): terminal alkynes can form a precipitate with ammoniacal silver trioxonitrate(V).

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids, Guided Practice

Instructional Procedures

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher asks pupils to mention fuels and products that come from petroleum (gas, petrol, kerosene, plastics). The teacher introduces hydrocarbons and writes the topic on the board.
Pupils’ Activity: Pupils mention examples and relate them to everyday use.
Learning Point: Many fuels and materials are made from hydrocarbons.

Step 2: Tetravalent Nature of Carbon

Time: 7 minutes
Teaching Skill: Explanation and Illustration
Teacher’s Activity: The teacher explains carbon tetravalency and catenation, then shows simple bonding patterns (single, double, triple) using a chart or board drawings.
Pupils’ Activity: Pupils copy key points and identify the number of bonds formed by carbon in examples.
Learning Point: Carbon forms four covalent bonds and can form chains and rings.

Step 3: Meaning and Examples of Hydrocarbons

Time: 6 minutes
Teaching Skill: Explanation and Questioning
Teacher’s Activity: The teacher defines hydrocarbons and classifies them into alkanes, alkenes, and alkynes with examples. The teacher guides pupils to state one example for each class.
Pupils’ Activity: Pupils list examples and write the formulae of methane, ethene, and ethyne.
Learning Point: Hydrocarbons contain only carbon and hydrogen and can be saturated or unsaturated.

Step 4: Homologous Series and Characteristics

Time: 6 minutes
Teaching Skill: Discussion and Board Work
Teacher’s Activity: The teacher defines homologous series and lists characteristics, emphasizing CH₂ difference between successive members. The teacher shows examples within the alkane series.
Pupils’ Activity: Pupils copy the definition, list characteristics, and state how ethane differs from propane in formula.
Learning Point: Members of a homologous series follow a pattern in formula and properties.

Step 5: IUPAC Naming of Simple Hydrocarbons

Time: 7 minutes
Teaching Skill: Guided Practice
Teacher’s Activity: The teacher presents prefixes and suffixes and guides pupils to name simple straight-chain hydrocarbons from C1 to C6. The teacher gives short class exercises for naming and formula writing.
Pupils’ Activity: Pupils name given hydrocarbons and write the correct names for C₃H₈, C₂H₄, and C₄H₁₀.
Learning Point: IUPAC naming uses carbon chain length and bond type.

Step 6: Saturated Hydrocarbons (Alkanes) Structure and Model Building

Time: 9 minutes
Teaching Skill: Demonstration and Activity Method
Teacher’s Activity: The teacher guides pupils to build simple carbon chain models for methane, ethane, propane, and butane using beads/model kits, then guides them to draw displayed/structural formulae and state the general formula C_nH_2n+2. The teacher demonstrates bromine water test briefly using samples/illustrations to show that alkanes do not decolourise bromine water under normal conditions.
Pupils’ Activity: Pupils build models, draw structures, and label them correctly. Pupils record the observation on bromine water test as guided.
Learning Point: Alkanes are saturated hydrocarbons with single bonds and general formula C_nH_2n+2.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

Define tetravalency of carbon and state the valency of carbon.
Define hydrocarbons and list one example each of an alkane, alkene, and alkyne.
Define homologous series and list three characteristics of a homologous series.
State the general formula of alkanes and name C₄H₁₀ using IUPAC rules.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 5 minutes
Teaching Skill: Summary and Reinforcement
Teacher’s Activity: The teacher summarizes carbon bonding, meaning of hydrocarbons, homologous series, IUPAC naming basics, and alkanes as saturated hydrocarbons. The teacher gives an assignment: list C1–C6 alkanes with formulae and draw the structures of methane, ethane, and propane.
Pupils’ Activity: Pupils copy the summary and assignment and ask questions where necessary.
Learning Point: Correct naming and structures of hydrocarbons depend on carbon bonding and homologous series patterns.

Lesson Keywords

Tetravalency – ability of carbon to form four covalent bonds.
Catenation – ability of carbon atoms to link with each other to form chains or rings.
Hydrocarbons – compounds containing only carbon and hydrogen.
Homologous series – family of organic compounds with same general formula and successive members differing by CH₂.
IUPAC naming – standard method of naming organic compounds based on chain length and bond type.
Alkanes – saturated hydrocarbons with general formula C_nH_2n+2.

Differentiation

Pupils who need support will use naming charts and partially completed structures to fill in bonds and hydrogens. Pupils who learn faster will name and draw additional straight-chain hydrocarbons and identify bond types, including simple position numbering for alkenes and alkynes.

Note for teachers using this lesson plan

Use models and clear board drawings to show carbon bonding and correct placement of hydrogen atoms. Emphasize that temperature must not be included in naming and that the suffix shows bond type. Handle bromine water and silver trioxonitrate(V) solution carefully and keep demonstrations teacher-led, with clear safety rules and proper disposal.