Lesson Note on Carbon And Its Compounds: Carbon Structure, Allotropes and Combustion for SS1 (SSS 1)

Class: Senior Secondary School 1 (SS1, SS 1, SSS1, SSS 1)
Term: 3rd Term
Week: 2
Age: 15 years
Duration: 45 minutes
Subject: Chemistry
Curriculum Theme: Chemistry
Previous Lesson: Water: Sources, Hard And Soft Water and Pollutants.
Topic: CARBON AND ITS COMPOUNDS
Subject Matter: structure of carbon, allotropes of carbon: charcoal, graphite and diamond, structure, properties and combustion of carbon allotropes

Specific Objectives

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

Cognitive Domain:

• Define carbon and its allotropes.
• Describe the atomic structure of carbon.
• State the structures and properties of diamond, graphite, and charcoal.
• Explain the combustion of carbon allotropes.

Affective Domain:

• Appreciate the importance of carbon compounds in daily life.
• Develop an interest in the study of carbon chemistry.

Psychomotor Domain:

• Draw simple representations of diamond and graphite structures.
• Handle samples of carbon allotropes safely.

Social Domain:

• Collaborate with peers to identify carbon-containing materials.

Reference Materials

The following resources were used in planning this lesson:

• 9 Years Basic Education Curriculum (Senior Secondary Chemistry)
• State Unified Scheme of Work (Chemistry SSS 1)
• New School Chemistry for Senior Secondary Schools by Osei Yaw Ababio
• Essential Chemistry for Senior Secondary Schools by Olumuyiwa A. Oyewole

Instructional Materials

The teacher will teach this lesson with the aid of:

• Samples of carbon-containing compounds such as stick, paper, and coal.
• Models or coloured beads to represent atomic structures.
• Charts showing the crystalline structures of diamond and graphite.

Rationale for the Lesson

This lesson helps pupils understand carbon, a fundamental element that forms the basis of all organic life and many important materials around us. Understanding carbon’s structure and its different forms enables pupils to grasp its versatility and significance in chemistry and daily living.

Prerequisite/Previous Knowledge

Pupils should have basic knowledge of elements, atoms, chemical bonding, and common compounds from earlier chemistry lessons.

Lesson Content/Board Summary

CARBON AND ITS COMPOUNDS

Introduction to Carbon

Carbon is a non-metallic element with atomic number 6 and atomic mass 12. It is found in Group 14 of the periodic table. Carbon is unique because it can form millions of compounds, more than any other element, due to its ability to bond with itself and other elements in various ways.

Structure of Carbon Atom

A carbon atom has 6 electrons arranged in electron shells as 2, 4. This means it has four valence electrons. Due to these four valence electrons, carbon can form four covalent bonds with other atoms, allowing for complex structures like chains, rings, and networks.

Allotropes of Carbon

Allotropy is the property of some chemical elements to exist in two or more different forms in the same physical state. These different forms are called allotropes. Carbon exhibits allotropy.

The following are the major allotropes of carbon:

• Diamond
• Graphite
• Amorphous carbon (e.g., charcoal, coal, coke, lampblack)

Diamond

Diamond is a crystalline allotrope of carbon.

The following are the structure and properties of diamond:

• Structure: Each carbon atom is covalently bonded to four other carbon atoms in a tetrahedral arrangement, forming a giant covalent network structure. There are no free electrons.
• Properties:
  • It is the hardest known natural substance.
  • It has a very high melting and boiling point.
  • It is an electrical insulator (does not conduct electricity).
  • It is transparent and refracts light strongly.
  • It is insoluble in all solvents.
• Uses: Used in jewellery, as cutting tools (drills, grinders), and for making abrasive powders.

Graphite

Graphite is another crystalline allotrope of carbon.

The following are the structure and properties of graphite:

• Structure: Carbon atoms are arranged in hexagonal layers. Within each layer, carbon atoms are covalently bonded to three other carbon atoms. The layers are held together by weak intermolecular forces (van der Waals forces), allowing them to slide over each other. Each carbon atom has one delocalised electron.
• Properties:
  • It is soft and slippery.
  • It is a good conductor of electricity due to delocalised electrons.
  • It is opaque and black.
  • It has a high melting point.
  • It is insoluble in all solvents.
• Uses: Used as a lubricant, in pencils (as ‘lead’), in electrodes, and as a moderator in nuclear reactors.

Amorphous Carbon (Charcoal)

Amorphous carbon refers to non-crystalline forms of carbon, lacking a definite crystal structure. Charcoal is a common example.

The following are the formation, structure and properties of charcoal:

• Formation: Charcoal is formed when wood or other organic matter is heated in the absence of air (destructive distillation).
• Structure: It has a disordered, irregular arrangement of carbon atoms, often with microscopic graphite-like regions. It is porous.
• Properties:
  • It is black and brittle.
  • It is a poor conductor of electricity.
  • It is porous and has a large surface area.
  • It is a good adsorbent.
• Uses: Used as fuel, in gas masks, in water purification, and in sugar refining (as activated charcoal).

Combustion of Carbon Allotropes

All allotropes of carbon burn in air or oxygen to form carbon dioxide (CO₂) if oxygen is in excess, or carbon monoxide (CO) if oxygen is limited.

The general combustion reaction is:

C(s) + O₂(g) → CO₂(g) (in excess oxygen)

2C(s) + O₂(g) → 2CO(g) (in limited oxygen)

Teaching Methods/Instructional Techniques

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

Instructional Procedures

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher greets the pupils and asks them to mention common materials they see around them, such as wood, paper, plastic, and food. The teacher then guides them to identify that many of these materials contain carbon.
Pupils’ Activity: Pupils mention various materials and respond to the teacher’s questions.
Learning Point: Pupils recall prior knowledge and connect carbon to everyday substances.

Step 2: Presentation of Subject Matter – Carbon and its Structure

Time: 8 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher defines carbon as an element and explains its atomic structure (atomic number 6, 4 valence electrons). The teacher uses a diagram or model to show how carbon atoms bond.
Pupils’ Activity: Pupils listen attentively, observe the model/diagram, and take notes.
Learning Point: Pupils understand the basic nature and bonding capacity of carbon.

Step 3: Introduction to Allotropes of Carbon

Time: 5 minutes
Teaching Skill: Definition/Concept Introduction
Teacher’s Activity: The teacher defines allotropy, explaining that carbon can exist in different forms. The teacher introduces diamond, graphite, and amorphous carbon as the main allotropes.
Pupils’ Activity: Pupils listen and understand the concept of allotropy.
Learning Point: Pupils learn the meaning of allotropy and identify carbon’s allotropes.

Step 4: Presentation of Allotropes – Diamond

Time: 7 minutes
Teaching Skill: Explanation/Visualisation
Teacher’s Activity: The teacher explains the structure of diamond using a chart or model, highlighting the tetrahedral arrangement and strong covalent bonds. The teacher then discusses its properties and uses.
Pupils’ Activity: Pupils observe the chart/model, listen to the explanation, and note down key points about diamond.
Learning Point: Pupils understand the structure, properties, and uses of diamond.

Step 5: Presentation of Allotropes – Graphite

Time: 7 minutes
Teaching Skill: Explanation/Comparison
Teacher’s Activity: The teacher explains the structure of graphite, emphasizing the layered hexagonal arrangement and the presence of delocalised electrons. The teacher then compares its properties and uses with those of diamond.
Pupils’ Activity: Pupils observe, listen, and identify the differences and similarities between diamond and graphite. They also note down the properties and uses of graphite.
Learning Point: Pupils understand the structure, properties, and uses of graphite and can compare it with diamond.

Step 6: Presentation of Allotropes – Amorphous Carbon (Charcoal)

Time: 6 minutes
Teaching Skill: Explanation/Examples
Teacher’s Activity: The teacher explains what amorphous carbon is, focusing on charcoal as an example. The teacher describes its formation, structure, properties, and uses.
Pupils’ Activity: Pupils listen, ask questions, and take notes on charcoal.
Learning Point: Pupils understand the characteristics and applications of amorphous carbon, specifically charcoal.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

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

1. Define allotropy.
2. List three allotropes of carbon.
3. State two properties of diamond.
4. Explain why graphite conducts electricity while diamond does not.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 2 minutes
Teaching Skill: Summarisation/Assignment
Teacher’s Activity: The teacher summarises the key points of the lesson, reiterating the importance of carbon and its allotropes. The teacher then assigns homework: “Draw and label the structures of diamond and graphite.”
Pupils’ Activity: Pupils listen to the summary and copy the homework.
Learning Point: Pupils consolidate their learning and prepare for further study.

Lesson Keywords

• Carbon – A non-metallic element with atomic number 6, fundamental to organic chemistry.
• Allotropy – The property of some elements to exist in two or more different forms in the same physical state.
• Allotropes – The different forms of an element exhibiting allotropy.
• Diamond – A crystalline allotrope of carbon, known for its hardness and insulating properties.
• Graphite – A crystalline allotrope of carbon, known for its softness, slipperiness, and electrical conductivity.
• Charcoal – An amorphous allotrope of carbon, formed by destructive distillation of organic matter.
• Combustion – A chemical process of burning, usually involving rapid reaction with oxygen and release of heat.

Differentiation

For pupils who grasp concepts quickly, the teacher can encourage them to research other allotropes of carbon like fullerenes or carbon nanotubes. For those who need more support, the teacher will provide simplified diagrams and allow more time for hands-on exploration of samples, focusing on basic identification and properties.

Note for teachers using this lesson plan

Ensure that actual samples of charcoal, graphite (e.g., pencil lead), and if possible, a visual representation of diamond are available for pupils to observe. Emphasise the link between the unique structures of diamond and graphite and their distinct properties.