Elements, Compounds, Mixtures and Common Elements for SS 1

Class: SS 1
Term: Second Term
Week: 1
Age: 15 years
Duration: 60 minutes
Subject: Chemistry
Curriculum Theme: The chemical world
Focal competence: Using symbols, formulae and equations to express the composition and interactions between elements and compounds
Key competencies/values: Creativity and Innovation; Innovation
Skills:

• Percentage composition of
• elements in a compound. empirical and molecular
• formulae of compounds
• Handling (setting up) of apparatus for the separation of given mixtures

Previous Lesson: Acids, Bases And Salts: Neutralization, Salt Preparation and Solubility
Topic: Elements, Compounds And Mixtures
Subject Matter: Meanings of elements, compounds and mixtures, Names of common elements, IUPAC names and symbols of common elements and compounds

Specific Objectives

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

Cognitive Domain

• Define elements, compounds, and mixtures.
• Explain the differences between elements, compounds, and mixtures.
• Identify and name common elements and compounds.
• State the IUPAC symbols for common elements and compounds.
• Describe basic atomic structure components: atomic number, mass number, and valency.

Affective Domain

• Appreciate the systematic classification of matter in chemistry.
• Value precision in using scientific terms and symbols.
• Demonstrate curiosity about the composition of matter.

Psychomotor Domain

• Group substances correctly as elements, compounds, or mixtures.
• Write the symbols of common elements.
• Construct simple atomic models of compounds.

Social Domain

• Collaborate effectively in group activities to identify and model chemical substances.

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
• New School Chemistry for Senior Secondary Schools by Osei Yaw Ababio
• 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
• Atomic structure models (if available)
• Cardboard papers
• Toothpicks
• Paper glue or adhesive
• Various samples of elements (e.g., copper wire, iron nail), compounds (e.g., salt, sugar, water), and mixtures (e.g., sand and salt, air).

Rationale for the Lesson

Understanding elements, compounds, and mixtures is foundational to all of chemistry. This lesson provides students with the basic vocabulary and conceptual framework needed to comprehend chemical reactions, properties of substances, and the composition of the world around them. It lays the groundwork for more advanced topics in chemical bonding and stoichiometry.

Prerequisite/Previous Knowledge

Students should have a basic understanding of matter and its states (solid, liquid, gas) from their Junior Secondary School science classes.

Lesson Content/Board Summary

Elements, Compounds And Mixtures

Meaning of Elements

An element is a pure substance that cannot be broken down into simpler substances by ordinary chemical or physical means. Elements are the fundamental building blocks of all matter.

1. Each element is made up of only one type of atom.
2. Elements are represented by unique chemical symbols.
3. Examples include Hydrogen (H), Oxygen (O), Iron (Fe), Gold (Au), Carbon (C), Nitrogen (N), Sodium (Na), Chlorine (Cl).

Meaning of Compounds

A compound is a pure substance formed when two or more different elements are chemically combined together in a fixed ratio by mass. The properties of a compound are entirely different from the properties of its constituent elements.

1. Compounds can only be separated into their constituent elements by chemical reactions.
2. They have a fixed melting point and boiling point.
3. Examples include Water (H₂O), Carbon Dioxide (CO₂), Sodium Chloride (NaCl), Glucose (C₆H₁₂O₆).

Meaning of Mixtures

A mixture is a substance containing two or more substances (elements or compounds) that are physically combined but not chemically bonded together. The components of a mixture retain their individual properties.

1. Components of a mixture can be separated by physical means (e.g., filtration, evaporation, magnetism).
2. The ratio of components in a mixture is not fixed.
3. Mixtures can be homogeneous (uniform composition, e.g., air, salt solution) or heterogeneous (non-uniform composition, e.g., sand and water, granite).
4. Examples include Air (mixture of gases), Salt solution (salt and water), Sand and iron filings, Crude oil.

Differences between Elements, Compounds and Mixtures

Common Elements and their IUPAC Symbols

The International Union of Pure and Applied Chemistry (IUPAC) provides standard names and symbols for elements.

1. Hydrogen (H)
2. Helium (He)
3. Lithium (Li)
4. Beryllium (Be)
5. Boron (B)
6. Carbon (C)
7. Nitrogen (N)
8. Oxygen (O)
9. Fluorine (F)
10. Neon (Ne)
11. Sodium (Na)
12. Magnesium (Mg)
13. Aluminium (Al)
14. Silicon (Si)
15. Phosphorus (P)
16. Sulphur (S)
17. Chlorine (Cl)
18. Argon (Ar)
19. Potassium (K)
20. Calcium (Ca)
21. Iron (Fe)
22. Copper (Cu)
23. Zinc (Zn)
24. Gold (Au)
25. Silver (Ag)
26. Lead (Pb)
27. Mercury (Hg)

Common Compounds and their IUPAC Formulae

Compounds are represented by chemical formulae showing the types and numbers of atoms of each element present.

1. Water (H₂O)
2. Carbon Dioxide (CO₂)
3. Sodium Chloride (NaCl) – Table Salt
4. Sulphuric Acid (H₂SO₄)
5. Ammonia (NH₃)
6. Methane (CH₄)
7. Glucose (C₆H₁₂O₆)
8. Calcium Carbonate (CaCO₃) – Limestone

Basic Atomic Structure

Atoms are the smallest particles of an element that retain the chemical identity of that element. They consist of a nucleus (containing protons and neutrons) and electrons orbiting the nucleus.

1. Atomic Number (Z): This is the number of protons in the nucleus of an atom. It determines the identity of an element. For a neutral atom, the atomic number is also equal to the number of electrons.
2. Mass Number (A): This is the total number of protons and neutrons in the nucleus of an atom. It represents the approximate mass of the atom.
3. Valency: This is the combining power of an element. It represents the number of electrons an atom will gain, lose, or share to achieve a stable electron configuration (usually a full outer shell).

Teaching Methods/Instructional Techniques

Discussion, Explanation, Question and Answer, Demonstration, Guided Practice, Group Work, Pair Work, Practical Activity.

Instructional Procedures

Step 1: Introduction

Time: 5 minutes

Teaching Skill: Recalling/Engaging

Teacher’s Activity: The teacher greets the students and reviews their previous knowledge of matter and its states. The teacher then introduces the topic by asking students to name different substances they encounter daily (e.g., water, air, salt, iron) and prompts them to think about what these substances are made of.

Pupils’ Activity: Pupils respond to questions and share examples of substances.

Learning Point: Matter and its composition

Step 2: Meaning of Elements

Time: 10 minutes

Teaching Skill: Explanation/Definition

Teacher’s Activity: The teacher defines an element as a pure substance that cannot be broken down further. The teacher uses the Periodic Table to show examples of elements and explains that each element is made of only one type of atom and has a unique symbol. The teacher guides students to identify and name the first twenty elements and other common elements from the Periodic Table.

Pupils’ Activity: Pupils listen, ask questions, and identify elements from the Periodic Table in pairs, writing down their names and symbols as guided by the teacher.

Learning Point: Definition of element

Step 3: Meaning of Compounds

Time: 10 minutes

Teaching Skill: Explanation/Demonstration

Teacher’s Activity: The teacher defines a compound as a substance formed when two or more elements chemically combine in a fixed ratio. The teacher explains that compounds have properties different from their constituent elements and can only be separated chemically. The teacher provides examples like water (H₂O) and salt (NaCl).

Pupils’ Activity: Pupils listen, take notes, and ask questions for clarification. They observe the examples provided.

Learning Point: Definition of compound

Step 4: Meaning of Mixtures

Time: 7 minutes

Teaching Skill: Explanation/Comparison

Teacher’s Activity: The teacher defines a mixture as a physical combination of two or more substances, where components retain their individual properties and can be separated physically. The teacher gives examples of homogeneous and heterogeneous mixtures (e.g., air, sand and water).

Pupils’ Activity: Pupils listen, take notes, and contribute examples of mixtures.

Learning Point: Definition of mixture

Step 5: Differences between Elements, Compounds and Mixtures

Time: 8 minutes

Teaching Skill: Comparison/Analysis

Teacher’s Activity: The teacher guides students in a discussion to highlight the key differences between elements, compounds, and mixtures, focusing on composition, separation methods, and properties. The teacher uses a table format on the board to summarize these differences.

Pupils’ Activity: Pupils actively participate in the discussion, comparing and contrasting the three types of substances. They copy the summary table from the board.

Learning Point: Distinguishing substances

Step 6: Atomic Structure and Model Building

Time: 10 minutes

Teaching Skill: Guided Practice/Activity

Teacher’s Activity: The teacher briefly explains atomic number, mass number, and valency. The teacher then guides students in groups to use cardboard papers and toothpicks to build simple atomic models of compounds (e.g., H₂O, CO₂) and write their corresponding formulae, reinforcing the concept of fixed ratios and valency.

Pupils’ Activity: Pupils work in groups to build atomic models, discuss, and write the formulae of the compounds, applying their understanding of atomic structure.

Learning Point: Atomic models and formulae

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 an element, a compound, and a mixture.
2. State two differences between a compound and a mixture.
3. Give the chemical symbol for Sodium and Iron.
4. Classify the following as element, compound, or mixture: Air, Water, Oxygen, Salt solution.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Understanding elements, compounds, mixtures

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 elements, compounds, mixtures, their differences, common examples, and basic atomic structure into their notebooks.

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

Learning Point: Recording lesson content

Step 9: Conclusion

Time: 5 minutes

Teaching Skill: Summarizing

Teacher’s Activity: The teacher briefly summarizes the main points of the lesson, reiterating the definitions and distinctions between elements, compounds, and mixtures, and their importance in chemistry.

Pupils’ Activity: Pupils listen and ask any final questions.

Learning Point: Lesson consolidation

Continuous Assessment/Further Study

Type: Homework

Instruction: Answer the following questions in your notebook.

1. List five common elements and their chemical symbols.
2. Explain why water is considered a compound and not a mixture.
3. Give two examples each of a homogeneous mixture and a heterogeneous mixture.
4. Research and write down the atomic number and valency for Carbon, Oxygen, and Sodium.

Lesson Keywords

• Element – A pure substance made of only one type of atom.
• Compound – A pure substance formed when two or more elements are chemically combined in a fixed ratio.
• Mixture – A substance containing two or more substances physically combined, retaining individual properties.
• Atom – The smallest unit of an element that retains its chemical identity.
• Symbol – A one or two-letter abbreviation for an element.
• Formula – A representation of a compound showing the types and numbers of atoms.
• Atomic Number – The number of protons in an atom’s nucleus.
• Mass Number – The total number of protons and neutrons in an atom’s nucleus.
• Valency – The combining power of an element.

Differentiation

Support: Provide simplified definitions and visual aids (e.g., flashcards with element symbols and names). Pair weaker students with stronger ones for group activities. Focus on identifying and defining the three main terms with basic examples.

Extension: Challenge advanced students to research the history of the discovery of specific elements or to explain how valency relates to the position of an element on the Periodic Table. Encourage them to find more complex examples of compounds and mixtures.

Suggested Lesson Videos

Search on YouTube for: elements compounds mixtures chemistry ss1