Atomic Structure, Constituents of the Atom and Properties of Subatomic Particles for SS 1

Class: SS 1
Term: Second Term
Week: 5
Age: 15 years
Duration: 60 minutes
Subject: Chemistry
Curriculum Theme: The chemical world
Focal competence: Determining the relative atomic masses
Key competencies/values: Creativity and Innovation; ICT and Digital Competencies; Digital Competencies; Innovation
Skills:

• Making models of electronic configuration of atoms
• Calculating relative atomic masses from isotopic data

Previous Lesson: Changes of state and Postulates of Dalton’s atomic theory
Topic: Atomic Structure
Subject Matter: Meaning of Atomic Structure, Constituents of the atom, Properties of subatomic particles

Specific Objectives

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

Cognitive Domain

• Define Atomic Structure.
• State the fundamental constituents of atoms.
• Discuss the properties of subatomic particles.
• Describe the arrangement of electrons around the nucleus and in orbitals.
• State the relative mass and charge of each subatomic particle.

Affective Domain

• Appreciate the importance of understanding atomic structure in chemistry.
• Show curiosity about the microscopic world of atoms.

Psychomotor Domain

• Use digital tools to simulate atomic structure.
• Draw simple models illustrating the arrangement of electrons.

Social Domain

• Collaborate in groups to discuss the characteristics of subatomic particles.

Reference Materials

The following resources were used in planning this lesson:

• 2025 New Revised Senior Secondary Education Curriculum (SSEC)
• Relevant State Unified Scheme of Work
• A suitable Chemistry textbook for SS 1
• The HeadTeacher Scheme of work For The New Revised Senior Secondary Education Curriculum (SSEC)

Instructional Materials

The teacher will teach this lesson with the aid of:

• Periodic Table of elements
• Charts showing the arrangement of electrons in atoms of common elements
• Video simulation of the arrangement of electrons in atoms of different elements
• CD or DVD players
• Projector
• Whiteboard and markers
• Computer/Tablet with internet access for simulations

Rationale for the Lesson

Understanding atomic structure is foundational to all of Chemistry, as it explains how elements behave and interact. This lesson provides students with the basic knowledge of what atoms are made of and how their components are arranged, which is essential for grasping concepts like chemical bonding, reactions, and the properties of matter. It also develops critical thinking and digital literacy skills through simulations.

Prerequisite/Previous Knowledge

Students should have a basic understanding of matter, elements, and compounds from their Junior Secondary School science classes.

Lesson Content/Board Summary

Atomic Structure

Meaning of Atomic Structure

Atomic structure refers to the arrangement of the fundamental particles within an atom. It describes how protons, neutrons, and electrons are organised to form an atom, which is the smallest unit of an element that retains the chemical identity of that element.

Constituents of the Atom

Atoms are composed of three primary subatomic particles:

1. Protons: Positively charged particles found in the nucleus of an atom.
2. Neutrons: Neutral particles (no charge) also found in the nucleus of an atom.
3. Electrons: Negatively charged particles that orbit the nucleus in specific energy levels or shells.

Properties of Subatomic Particles

Each subatomic particle has distinct properties regarding mass, charge, and location within the atom:

1. Proton (p⁺):
   1. Charge: +1 (positive)
   2. Relative Mass: Approximately 1 atomic mass unit (amu)
   3. Actual Mass: (1.672 times 10^{-27}) kg
   4. Location: Nucleus
   5. Role: Determines the identity of the element (atomic number).
2. Neutron (n⁰):
   1. Charge: 0 (neutral)
   2. Relative Mass: Approximately 1 atomic mass unit (amu)
   3. Actual Mass: (1.675 times 10^{-27}) kg
   4. Location: Nucleus
   5. Role: Contributes to the mass of the atom and helps stabilise the nucleus.
3. Electron (e^–):
   1. Charge: -1 (negative)
   2. Relative Mass: Approximately ( frac{1}{1836} ) of a proton’s mass (negligible compared to protons and neutrons)
   3. Actual Mass: (9.109 times 10^{-31}) kg
   4. Location: Orbiting the nucleus in electron shells/energy levels
   5. Role: Involved in chemical bonding and determines the chemical properties of an element.

Arrangement of Electrons Around the Nucleus and Orbitals

Electrons are not randomly scattered around the nucleus but occupy specific energy levels or shells. These shells are often represented as concentric circles around the nucleus, with electrons filling them from the innermost shell outwards.

1. Electron Shells/Energy Levels:
   1. The first shell (K-shell) can hold a maximum of 2 electrons.
   2. The second shell (L-shell) can hold a maximum of 8 electrons.
   3. The third shell (M-shell) can hold a maximum of 18 electrons.
   4. The general formula for the maximum number of electrons in a shell is (2n^2), where (n) is the shell number.
2. Orbitals:
   1. Within each electron shell, electrons occupy regions of space called orbitals.
   2. An orbital is a region around the nucleus where there is a high probability of finding an electron.
   3. Each orbital can hold a maximum of two electrons with opposite spins.
   4. Common types of orbitals include s, p, d, and f orbitals, which have different shapes and energy levels.
3. Electronic Configuration:
   1. This is the distribution of electrons of an atom or molecule in atomic or molecular orbitals.
   2. For example, the electronic configuration of Oxygen (8 electrons) is 2, 6, meaning 2 electrons in the first shell and 6 in the second.

Teaching Methods/Instructional Techniques

Discussion, Explanation, Question and Answer, Demonstration, Guided Practice, Group Work, Simulation

Instructional Procedures

Step 1: Introduction

Time: 5 minutes

Teaching Skill: Activating Prior Knowledge

Teacher’s Activity: The teacher greets the students and asks them to recall what they learned about matter and elements in JSS science. The teacher then introduces the topic “Atomic Structure” by asking what they think an atom is made of.

Pupils’ Activity: Pupils respond to the questions and share their initial ideas about atoms.

Learning Point: Recall of basic matter concepts

Step 2: Meaning of Atomic Structure

Time: 10 minutes

Teaching Skill: Explanation/Definition

Teacher’s Activity: The teacher explains the meaning of atomic structure, emphasising that atoms are not indivisible but have an internal arrangement of particles. The teacher uses diagrams or a chart to illustrate this.

Pupils’ Activity: Pupils listen attentively, observe the diagrams, and ask questions for clarification.

Learning Point: Definition of atomic structure

Step 3: Constituents of the Atom

Time: 10 minutes

Teaching Skill: Identification/Listing

Teacher’s Activity: The teacher introduces the three fundamental constituents of an atom: protons, neutrons, and electrons. The teacher points them out on a diagram of an atom and states their basic characteristics.

Pupils’ Activity: Pupils identify the subatomic particles and note their names.

Learning Point: Fundamental constituents of atoms

Step 4: Properties of Subatomic Particles (Charge and Location)

Time: 10 minutes

Teaching Skill: Discussion/Elaboration

Teacher’s Activity: The teacher discusses the charge and location of each subatomic particle (protons are positive in the nucleus, neutrons are neutral in the nucleus, electrons are negative orbiting the nucleus). The teacher uses the Periodic Table to show how the number of protons defines an element.

Pupils’ Activity: Pupils participate in the discussion, noting the charges and locations of the particles.

Learning Point: Charge and location of particles

Step 5: Properties of Subatomic Particles (Relative Mass)

Time: 5 minutes

Teaching Skill: Explanation/Comparison

Teacher’s Activity: The teacher explains the relative masses of protons, neutrons, and electrons, highlighting that electrons have negligible mass compared to protons and neutrons. The teacher states the approximate relative mass for each.

Pupils’ Activity: Pupils listen and record the relative masses of the subatomic particles.

Learning Point: Relative masses of subatomic particles

Step 6: Arrangement of Electrons and Orbitals

Time: 5 minutes

Teaching Skill: Demonstration/Simulation

Teacher’s Activity: The teacher guides students to use digital tools (video simulation) to observe the arrangement of electrons in shells/energy levels and the concept of orbitals. The teacher explains how electrons fill these shells.

Pupils’ Activity: Pupils observe the simulation and discuss the arrangement of electrons, asking questions about orbitals.

Learning Point: Electron arrangement and orbitals

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. What is atomic structure?
2. Name the three fundamental constituents of an atom.
3. Describe the charge and location of a proton.
4. Which subatomic particle has a negligible mass?

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Assessment of atomic structure understanding

Step 8: Note-Taking

Time: 10 minutes

Teaching Skill: Guided Writing

Teacher’s Activity: The teacher guides pupils/students to copy the essential Board Summary notes on the meaning of atomic structure, constituents, and properties of subatomic particles into their notebooks.

Pupils’ Activity: Pupils/students copy the notes carefully into their notebooks.

Learning Point: Recording of lesson content

Step 9: Conclusion

Time: 5 minutes

Teaching Skill: Consolidation

Teacher’s Activity: The teacher summarises the key points of the lesson, reinforcing the idea that understanding atomic structure is crucial for further studies in Chemistry. The teacher encourages students to review their notes.

Pupils’ Activity: Pupils listen to the summary and prepare for the next lesson.

Learning Point: Consolidation of atomic structure concepts

Continuous Assessment/Further Study

Type: Homework

Instruction: Answer the following questions in your notebook:

1. Draw a simple diagram of an atom, labelling the nucleus, protons, neutrons, and electrons.
2. Compare and contrast the properties (mass, charge, location) of protons, neutrons, and electrons in a table.
3. Explain why an atom is generally considered electrically neutral.

Lesson Keywords

• Atom – The smallest unit of an element that retains the chemical identity of that element.
• Atomic Structure – The arrangement of subatomic particles (protons, neutrons, electrons) within an atom.
• Proton – A positively charged subatomic particle found in the nucleus.
• Neutron – A neutral subatomic particle found in the nucleus.
• Electron – A negatively charged subatomic particle that orbits the nucleus.
• Nucleus – The dense, central part of an atom containing protons and neutrons.
• Electron Shells – Energy levels where electrons are found orbiting the nucleus.
• Orbitals – Regions within electron shells where there is a high probability of finding electrons.

Differentiation

For struggling learners: Provide simplified diagrams and charts. Focus on identifying the particles and their charges and locations. Use physical models if available for hands-on learning. Pair them with more advanced learners for peer support.

For advanced learners: Encourage them to research the discovery of subatomic particles or delve deeper into the shapes and types of orbitals (s, p, d, f). Challenge them to explain how the number of electrons affects an atom’s reactivity.

Suggested Lesson Videos

Search on YouTube for: atomic structure for ss1 chemistry