Class: Senior Secondary School 2 (SS2 / SSS2)
Term: Second Term
Week: 8
Age: 16 years
Duration: 45 minutes
Subject: Chemistry
Curriculum Theme: Non-metals and their Compounds
Previous Lesson: Halogens: Compounds, Uses and Chlorine Preparation.
Topic: NITROGEN
Subject Matter: Meaning of nitrogen (a colourless gas that makes up most of air), general properties of nitrogen family group V elements, laboratory preparation of nitrogen.

Specific Objectives

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

Cognitive Domain:

Define nitrogen.
State at least three general properties of the nitrogen family (Group V elements).
Describe the laboratory preparation of nitrogen.
Write the balanced chemical equation for the laboratory preparation of nitrogen.
List at least two physical properties of nitrogen.
Mention at least two uses of nitrogen.

Affective Domain:

Appreciate the importance of nitrogen in the atmosphere and in industrial applications.
Show interest in observing chemical reactions and properties of elements.

Psychomotor Domain:

Draw a simple diagram of the laboratory setup for nitrogen preparation.
Record the procedure and observations during the demonstration of nitrogen preparation.

Participate actively in class discussions about nitrogen and its compounds.
Collaborate in identifying the properties and uses of nitrogen.

Reference Materials

The following resources were used in planning this lesson:

Senior Secondary Schools Education Curriculum
State Unified Scheme of Work
New School Chemistry for Senior Secondary Schools by Osei Yaw Ababio

Instructional Materials

The teacher will teach this lesson with the aid of:

Charts tabulating properties of nitrogen group (Group 15 elements).
Diagrams illustrating the laboratory preparation of nitrogen.
A periodic table.
Sample chemicals (ammonium chloride, sodium nitrite) and laboratory apparatus (test tubes, delivery tube, gas jar, trough, Bunsen burner) for demonstration.

Rationale for the Lesson

This lesson helps pupils understand nitrogen, an important component of the air we breathe and a key element in many industrial processes. Learning about its properties and preparation provides a foundational understanding of non-metal chemistry and its applications in daily life.

Prerequisite/Previous Knowledge

Pupils are expected to have basic knowledge of elements, the periodic table, simple chemical reactions, and the composition of air.

Lesson Content/Board Summary

NITROGEN

Meaning of Nitrogen

Nitrogen is a colourless, odourless, and tasteless diatomic gas (N₂) that constitutes about 78% by volume of the Earth’s atmosphere. It is relatively unreactive at room temperature.

General Properties of Nitrogen Family (Group 15 / V Elements)

The nitrogen family consists of nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), and bismuth (Bi). The following are their general properties:

Electronic Configuration: All elements in this group have five valence electrons with a general outer electronic configuration of ns²np³.
Oxidation States: Common oxidation states include -3, +3, and +5. Nitrogen can exhibit a wide range of oxidation states.
Physical State: Nitrogen is a gas, while phosphorus, arsenic, antimony, and bismuth are solids at room temperature.
Metallic Character: Non-metallic character decreases down the group. Nitrogen and phosphorus are non-metals, arsenic and antimony are metalloids, and bismuth is a metal.
Allotropy: Phosphorus, arsenic, and antimony exhibit allotropy (existence in different physical forms).

Laboratory Preparation of Nitrogen

Nitrogen can be prepared in the laboratory by heating an aqueous solution containing ammonium chloride (NH₄Cl) and sodium nitrite (NaNO₂).

Principle: The reaction involves the decomposition of ammonium nitrite (NH₄NO₂), which is formed in situ from the reaction of ammonium chloride and sodium nitrite.

Chemical Equation:

NH₄Cl(aq) + NaNO₂(aq) → N₂(g) + 2H₂O(l) + NaCl(aq)

Procedure:

Step 1: Mix concentrated solutions of ammonium chloride and sodium nitrite in a round-bottom flask.
Step 2: Heat the mixture gently. Nitrogen gas is evolved.
Step 3: Collect the nitrogen gas by the downward displacement of water, as it is sparingly soluble in water.
Step 4: Impurities such as nitric oxide (NO) and nitric acid (HNO₃) can be removed by passing the gas through an acidified ferrous sulphate solution and then through water.

Note: A simple diagram showing a round-bottom flask, delivery tube, gas jar, and trough for water displacement should be drawn.

Physical Properties of Nitrogen

The following are the physical properties of nitrogen:

It is a colourless, odourless, and tasteless gas.
It is sparingly soluble in water.
It is slightly less dense than air.
It is non-flammable and does not support combustion.
It is chemically inert at room temperature due to the strong triple bond between its atoms.

Uses of Nitrogen

The following are some uses of nitrogen:

It is used in the manufacture of ammonia (Haber process), nitric acid, and various nitrogenous fertilizers.
It provides an inert atmosphere in light bulbs, food packaging, and in some industrial processes to prevent oxidation.
Liquid nitrogen is used as a refrigerant for preserving biological samples and in cryosurgery.
It is used to inflate car tyres and aircraft landing gears.

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 what they know about the air they breathe, leading them to mention nitrogen as a major component.
Pupils’ Activity: Pupils respond to the teacher’s questions and state that air contains nitrogen.
Learning Point: Pupils recall prior knowledge about air composition and are introduced to nitrogen.

Step 2: Meaning of Nitrogen

Time: 5 minutes
Teaching Skill: Explanation/Definition
Teacher’s Activity: The teacher explains the meaning of nitrogen as a colourless, odourless, tasteless, diatomic gas that makes up about 78% of the atmosphere.
Pupils’ Activity: Pupils listen attentively and copy the definition into their notebooks.
Learning Point: Pupils understand the basic definition and characteristics of nitrogen.

Step 3: General Properties of Nitrogen Family

Time: 10 minutes
Teaching Skill: Explanation/Use of Visual Aids
Teacher’s Activity: The teacher uses a chart and the periodic table to explain the general properties of Group 15 (nitrogen family) elements, discussing electronic configuration, oxidation states, physical states, and metallic character.
Pupils’ Activity: Pupils observe the charts, ask questions, and note down the key properties of the nitrogen family.
Learning Point: Pupils identify and understand the characteristic properties of elements in the nitrogen family.

Step 4: Laboratory Preparation of Nitrogen (Reaction & Equation)

Time: 10 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher explains the principle behind the laboratory preparation of nitrogen and writes the balanced chemical equation on the board.
Pupils’ Activity: Pupils observe, listen, and copy the chemical equation into their notebooks.
Learning Point: Pupils learn the chemical reaction and equation for preparing nitrogen in the laboratory.

Step 5: Laboratory Preparation of Nitrogen (Procedure & Diagram)

Time: 5 minutes
Teaching Skill: Demonstration/Illustration
Teacher’s Activity: The teacher demonstrates or illustrates the laboratory setup and procedure for preparing nitrogen, emphasizing safety precautions and collection method.
Pupils’ Activity: Pupils observe the demonstration/illustration and draw the diagram in their notebooks.
Learning Point: Pupils understand the practical steps and apparatus used for nitrogen preparation.

Step 6: Physical Properties and Uses of Nitrogen

Time: 5 minutes
Teaching Skill: Explanation/Listing
Teacher’s Activity: The teacher explains the physical properties of nitrogen and discusses its various uses in industries and daily life.
Pupils’ Activity: Pupils listen and list the physical properties and uses of nitrogen.
Learning Point: Pupils identify the physical characteristics and practical applications of nitrogen.

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 nitrogen.
List three general properties of the nitrogen family (Group 15 elements).
Describe the laboratory preparation of nitrogen, including the balanced chemical equation.
State two physical properties of nitrogen.
Mention two uses of nitrogen.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: Immediately after review
Teaching Skill: Summarization
Teacher’s Activity: The teacher summarizes the key points of the lesson, emphasizing the importance of nitrogen and its compounds. The teacher then assigns homework.
Pupils’ Activity: Pupils listen to the summary and copy down the assigned homework.
Learning Point: Pupils consolidate their learning and receive further tasks.

Lesson Keywords

Nitrogen – A colourless, odourless, tasteless diatomic gas making up about 78% of the atmosphere.
Group V elements – Elements in Group 15 of the periodic table, also known as the nitrogen family.
Inert gas – A gas that is chemically unreactive under normal conditions.
Ammonium chloride – A chemical compound (NH₄Cl) used in the laboratory preparation of nitrogen.
Sodium nitrite – A chemical compound (NaNO₂) used in the laboratory preparation of nitrogen.

Differentiation

For pupils who are struggling, the teacher will provide simplified notes and focus on the most essential definitions and the primary chemical equation. Advanced learners will be encouraged to research other methods of nitrogen preparation or the industrial uses of nitrogen compounds.

Note for teachers using this lesson plan

Ensure that all safety precautions are strictly followed if demonstrating the laboratory preparation of nitrogen. Emphasize the inert nature of nitrogen at room temperature and its importance in biological and industrial processes. Encourage pupils to use the periodic table to understand group trends.