Understanding the distinction between physical and chemical changes is fundamental in the study of matter and its properties. For students in the IB Middle Years Programme (MYP) 1-3 Science curriculum, grasping these concepts is essential for exploring the behavior of substances in various contexts. This knowledge not only forms the basis for more advanced scientific topics but also enhances critical thinking and analytical skills.

Key Concepts

What Are Physical Changes?

A physical change refers to a transformation in the physical properties of a substance without altering its chemical composition. These changes are usually reversible and do not involve the formation of new substances. Common examples include changes in state (such as melting, freezing, and vaporization), alterations in shape or size, and dissolution. Physical changes are governed by physical laws and can often be explained by changes in energy or the application of force.

Examples of Physical Changes

Melting of Ice: When ice melts to form water, the substance remains H₂O, and the process is reversible by freezing the water again.
Breaking Glass: Shattering glass changes its shape but not its chemical structure.
Dissolving Salt in Water: Salt (NaCl) dissolves in water to form a homogeneous solution, but the salt can be recovered through evaporation.

What Are Chemical Changes?

Chemical changes involve transformations that alter the chemical composition of substances, resulting in the formation of one or more new substances with different properties. These changes are typically irreversible under normal conditions and involve the making or breaking of chemical bonds. Chemical changes are often accompanied by energy changes, such as heat, light, or sound, and can be identified by indicators like color changes, gas production, or precipitate formation.

Examples of Chemical Changes

Combustion: Burning of wood converts it into ash, carbon dioxide, and water vapor.
Rusting of Iron: Iron reacts with oxygen and moisture to form iron oxide, commonly known as rust.
Baking a Cake: Ingredients undergo chemical reactions to form a new structure and flavor profile.

Identifying Physical and Chemical Changes

Distinguishing between physical and chemical changes can be achieved by observing certain characteristics:

Reversibility: Physical changes are generally reversible, while chemical changes are not easily reversed.
Energy Changes: Chemical changes often involve significant energy changes, such as heat or light, unlike most physical changes.
Formation of New Substances: The emergence of new substances indicates a chemical change, whereas no new substances are formed in physical changes.

The Role of Energy in Physical and Chemical Changes

Energy plays a crucial role in both physical and chemical changes. In physical changes, energy is often involved in changing the state of matter. For example, melting ice requires the absorption of heat energy, described by the equation:

$$ \text{Heat energy} = m \times \Delta H_{\text{fusion}} $$

Where:

m = mass of the substance
ΔH_fusion = enthalpy of fusion

In chemical changes, energy is either absorbed or released during the formation or breaking of chemical bonds. Exothermic reactions release energy, while endothermic reactions absorb energy. For instance, the combustion of methane can be represented as:

$$ \text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O} + \text{Energy} $$>

Conservation of Mass in Physical and Chemical Changes

The law of conservation of mass states that mass is neither created nor destroyed in a closed system during both physical and chemical changes. In physical changes, the mass remains constant as the substance changes form. In chemical changes, although the form and properties of the substances change, the total mass of the reactants equals the total mass of the products.

For example, when melting ice:

$$ \text{H}_2\text{O (solid)} \rightarrow \text{H}_2\text{O (liquid)} $$>

The mass before and after melting remains the same.

In a chemical reaction such as the reaction between hydrogen and oxygen to form water:

$$ 2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O} $$>

The mass of hydrogen and oxygen used equals the mass of water produced.

Practical Applications of Physical Changes

Recycling: Physical changes are fundamental in recycling processes where materials are melted, reshaped, or physically altered to create new products.
Cooking: Many cooking processes involve physical changes, such as chopping, mixing, and heating ingredients.
Manufacturing: Processes like molding, cutting, and assembling materials are based on physical transformations.

Practical Applications of Chemical Changes

Medicine: Chemical changes are involved in the synthesis of pharmaceuticals and the metabolism of drugs within the body.
Energy Production: Combustion reactions release energy used in power generation and transportation.
Environmental Processes: Natural chemical reactions, such as photosynthesis and decomposition, are essential for ecosystem sustainability.

Balancing Chemical Equations

Balancing chemical equations ensures that the law of conservation of mass is upheld by having the same number of atoms of each element on both sides of the equation. For example, the combustion of methane is balanced as:

$$ \text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O} $$>

Here, there is one carbon atom, four hydrogen atoms, and four oxygen atoms on both sides of the equation.

Indicators of Chemical Changes

Chemical changes can often be identified by certain indicators:

Color Change: A substance changes color, indicating a chemical transformation.
Gas Production: The formation of bubbles or fumes suggests a chemical reaction.
Precipitate Formation: A solid forms from a solution, signaling a new substance's creation.
Temperature Change: The release or absorption of heat during the reaction.

Reversibility of Changes

Understanding whether a change is reversible helps differentiate between physical and chemical changes. Physical changes, such as freezing water into ice, are typically reversible. In contrast, chemical changes, like burning paper, result in substances that cannot be easily reverted to their original forms.

Energy Diagrams in Physical and Chemical Changes

Energy diagrams visually represent the energy changes during reactions. In physical changes, the energy input or output is usually lower compared to chemical changes. For example, during melting, energy is absorbed to break intermolecular forces, represented by an upward slope in the energy diagram. In contrast, exothermic chemical reactions show a significant release of energy, depicted as a steep downward slope.

Understanding Endothermic and Exothermic Reactions

Chemical reactions can be categorized based on energy exchange:

Endothermic Reactions: These reactions absorb energy from the surroundings, resulting in a temperature drop. An example is the decomposition of calcium carbonate:

$$ \text{CaCO}_3 \rightarrow \text{CaO} + \text{CO}_2 $$>

Exothermic Reactions: These reactions release energy, often in the form of heat, leading to a temperature increase. An example is the combustion of hydrogen gas:

$$ 2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O} + \text{Energy} $$>

Real-World Examples of Physical and Chemical Changes

Recognizing real-world examples helps solidify the concepts:

Physical Change: Boiling water for cooking.
Chemical Change: Photosynthesis in plants converting carbon dioxide and water into glucose and oxygen.
Physical Change: Crushing a can without altering its material composition.
Chemical Change: Baking bread, where yeast fermentation causes dough to rise.

The Importance of Distinguishing Between Change Types

Identifying whether a change is physical or chemical is crucial in various scientific and practical applications. It affects how substances are handled, processed, and utilized in industries such as pharmaceuticals, manufacturing, and environmental management. Additionally, this understanding is foundational for further studies in chemistry, biology, and physics.

Common Misconceptions

Students often confuse physical and chemical changes due to overlapping characteristics. For example, dissolving sugar in water is a physical change, but if a substance decomposes in solution, it may appear as a chemical change. Clear differentiation relies on identifying whether new substances are formed and whether the change is reversible.

Comparison Table

Aspect	Physical Changes	Chemical Changes
Definition	Changes in the physical properties of a substance without altering its chemical composition.	Transformations that result in the formation of one or more new substances with different chemical compositions.
Reversibility	Generally reversible.	Usually irreversible under normal conditions.
Energy Changes	Involves changes in physical state, often requiring energy input or release.	Involves significant energy changes, such as heat release or absorption.
Examples	Melting ice, tearing paper, dissolving salt.	Burning wood, rusting iron, baking a cake.
Mass Conservation	Mass remains constant.	Mass remains constant, but new substances are formed.
Change in Chemical Properties	No change in chemical properties.	Change in chemical properties.

Summary and Key Takeaways

Physical changes alter the form of a substance without changing its chemical identity.
Chemical changes result in new substances with different properties.
Energy changes and reversibility are key indicators distinguishing the two types of changes.
Understanding these changes is essential for applications in various scientific and everyday contexts.
Accurate identification aids in predicting outcomes and managing materials effectively.

Examiner Tip

Tips

1. **Use Mnemonics:** Remember "PERM" for Physical vs. Chemical Changes: Physical is **P**hase change, **E**nergy change, **R**eversible, and **M**aintains composition. Chemical changes involve forming new substances.

2. **Identify Indicators:** Look for signs like color change, gas production, or temperature change to determine if a reaction is chemical.

3. **Practice Balancing Equations:** Regularly practice balancing chemical equations to reinforce your understanding of mass conservation in chemical changes.

4. **Real-World Applications:** Relate concepts to everyday scenarios, such as cooking or recycling, to better grasp the differences between physical and chemical changes.

Did You Know

1. **Lightning Strikes as Chemical Changes:** When lightning strikes, it causes chemical changes by breaking molecular bonds and forming new compounds like ozone. This natural phenomenon showcases the powerful energy transformations involved in chemical reactions.

2. **Reversible Chemical Changes in Nature:** While most chemical changes are irreversible, certain biological processes like photosynthesis and respiration involve reversible chemical reactions that are essential for life on Earth.

3. **Physical Changes in Space:** In the vacuum of space, physical changes such as sublimation can occur without the presence of atmospheric pressure, leading to fascinating transformations of materials exposed to extreme conditions.

Common Mistakes

Mistake 1: Confusing dissolution with a chemical change.
Incorrect: Believing that dissolving sugar in water is a chemical reaction.
Correct: Dissolving sugar is a physical change because the chemical composition of sugar remains unchanged.

Mistake 2: Assuming all energy changes indicate a chemical change.
Incorrect: Thinking that melting ice is a chemical change due to energy absorption.
Correct: Melting ice is a physical change as it only involves a change in state, not in chemical composition.

Mistake 3: Overlooking the formation of new substances.
Incorrect: Not recognizing that rust is a new substance formed from iron and oxygen.
Correct: Identifying rust formation as a chemical change because it results in the creation of iron oxide.

FAQ

What is the main difference between physical and chemical changes?

Physical changes alter the form or appearance of a substance without changing its chemical composition, whereas chemical changes result in the formation of new substances with different chemical properties.

While most physical changes are reversible, some can be irreversible depending on the conditions, such as breaking a glass into pieces.

How can you identify a chemical change?

Chemical changes can be identified by indicators such as color change, gas production, formation of a precipitate, or temperature change during the reaction.

Is dissolving sugar in water a physical or chemical change?

Dissolving sugar in water is a physical change because it involves mixing without altering the chemical structure of sugar.

Why is balancing chemical equations important?

Balancing chemical equations is crucial to ensure the law of conservation of mass is satisfied, showing that the same number of atoms of each element are present on both sides of the reaction.

Can energy changes occur in physical changes?

Yes, energy changes such as heat absorption or release can occur in physical changes, like melting or freezing, but they are typically less significant than those in chemical changes.

1. Systems in Organisms

1.1 Skeletal and Muscular Systems

1.1.1 Functions of the Human Skeleton

1.1.2 Types of Joints and Their Movement

1.1.3 Major Muscles in the Human Body

1.1.4 How Muscles Work in Pairs (Antagonistic Muscles)

1.1.5 Protection, Support, and Movement

1.2 Reproductive Systems (Introductory)

1.2.1 Introduction to Human Reproductive Organs

1.2.2 Male and Female Reproductive Structures

1.2.3 Basic Stages of Human Reproduction

1.2.4 Fertilization and Development (Simplified)

1.2.5 Importance of Reproduction for Species Continuity

1.3 Excretion and Homeostasis (Introductory)

1.3.1 Concept of Excretion and Examples in Humans

1.3.2 Role of Kidneys and Urinary System

1.3.3 Sweating and Carbon Dioxide Removal

1.3.4 Simple Explanation of Homeostasis

1.3.5 Importance of Maintaining Internal Balance

1.4 Interdependence in Organisms

1.4.1 Transport of Nutrients and Oxygen to Cells

1.4.2 Interaction Between Digestive and Circulatory Systems

1.4.3 How Systems Work Together in the Human Body

1.4.4 Consequences of System Failure

1.4.5 Case Studies of System Interactions in Daily Life

1.5 Human Digestive System

1.5.1 Organs of the Digestive System and Their Functions

1.5.2 Mechanical and Chemical Digestion

1.5.3 Role of Enzymes in Digestion (Introductory)

1.5.4 Absorption of Nutrients in the Small Intestine

1.5.5 Journey of Food Through the Digestive Tract

1.6 Respiratory and Circulatory Systems

1.6.1 Structure and Function of the Respiratory System

1.6.2 Gas Exchange in the Alveoli

1.6.3 Structure and Function of the Heart

1.6.4 Blood Vessels: Arteries, Veins, Capillaries

1.6.5 Link Between Respiration and Circulation

2. Cells and Living Systems

2.1 Levels of Biological Organization

2.1.1 From Cells to Tissues, Organs, and Systems

2.1.2 Organism Hierarchy: Cells to Whole Organism

2.1.3 Examples in Humans and Plants

2.1.4 Interdependence of Levels

2.1.5 Importance of Structural Organization in Biology

2.2 Specialized Cells and Their Functions

2.2.1 Definition and Need for Specialization

2.2.2 Examples: Nerve, Muscle, Red Blood, Root Hair Cells

2.2.3 Adaptations of Specialized Cells

2.2.4 Comparing Specialized vs Unspecialized Cells

2.2.5 Stem Cells and Potential (Introductory)

2.3 Plant and Animal Cell Differences

2.3.1 Organelles Unique to Plant Cells (Chloroplasts, Cell Wall)

2.3.2 Vacuole Differences and Functions

2.3.3 Comparing Diagrams of Plant vs Animal Cells

2.3.4 Functions Related to Structure in Both Cells

2.3.5 Importance of Differences for Life Processes

2.4 Unicellular vs Multicellular Organisms

2.4.1 Definition and Characteristics of Unicellular Organisms

2.4.2 Examples of Bacteria, Amoeba, and Paramecium

2.4.3 Functions Performed by One Cell

2.4.4 Advantages and Limitations of Unicellularity

2.4.5 Comparing with Multicellular Organisms

2.5 Structure and Function of Cells

2.5.1 Basic Structure of Plant and Animal Cells

2.5.2 Functions of Cell Organelles (Nucleus, Cytoplasm, etc.)

2.5.3 Comparing Prokaryotic and Eukaryotic Cells (Introductory)

2.5.4 Importance of Cell Membrane and Cytoplasm

2.5.5 Understanding the Cell as the Basic Unit of Life

2.6 Microscopes and Cell Observation

2.6.1 Parts and Functions of a Light Microscope

2.6.2 Using a Microscope to View Prepared Slides

2.6.3 Making Temporary Slides (Onion Cells, etc.)

2.6.4 Magnification and Field of View

2.6.5 Safety and Handling of Microscopes

3. Matter and Its Properties

3.1 Elements, Compounds, and Mixtures

3.1.1 Definition of Elements and Symbols

3.1.2 Compounds and Chemical Formulae

3.1.3 Differences Between Compounds and Mixtures

3.1.4 Types of Mixtures: Homogeneous and Heterogeneous

3.1.5 Identifying Substances from Their Properties

3.2 Atomic Structure (Introductory)

3.2.1 Atoms and Their Subatomic Particles

3.2.2 Structure of a Simple Atom

3.2.3 Atomic Number and Mass Number (Basic)

3.2.4 Introduction to the Concept of Ions

3.2.5 Historical Models of the Atom (Simplified)

3.3 Separation Techniques

3.3.1 Filtration and Evaporation

3.3.2 Distillation and Chromatography (Introductory)

3.3.3 Using Magnets and Sieving

3.3.4 Choosing Appropriate Separation Methods

3.3.5 Practical Lab Applications of Separation Techniques

3.4 Acids, Bases, and Indicators

3.4.1 Definition and Properties of Acids and Bases

3.4.2 Using Litmus, Universal Indicator, and pH Scale

3.4.3 Common Acids and Bases in Everyday Life

3.4.4 Neutralization Reactions (Introductory)

3.4.5 Safety and Handling of Acids and Bases in the Lab

3.5 States of Matter and Particle Theory

3.5.1 Solids, Liquids, and Gases: Basic Properties

3.5.2 Particle Model of Matter

3.5.3 Changes of State: Melting, Boiling, Condensation, Freezing

3.5.4 Energy and Particle Movement in State Changes

3.5.5 Applications of Particle Theory in Real Life

3.6 Physical and Chemical Changes

3.6.1 Definition and Comparison of Physical and Chemical Changes

3.6.2 Signs of a Chemical Change

3.6.3 Examples of Reversible and Irreversible Changes

3.6.4 Mixtures and Changes in States

3.6.5 Investigating Changes in the Lab

4. Ecology and Environment

4.1 Ecosystems and Biomes

4.1.1 Definition and Components of an Ecosystem

4.1.2 Major Biomes of the World

4.1.3 Interactions Between Biotic and Abiotic Factors

4.1.4 Population and Community Dynamics

4.1.5 Human Activities Affecting Ecosystems

4.2 Energy Flow and Pyramids

4.2.1 Energy Loss at Each Trophic Level

4.2.2 Pyramid of Numbers and Biomass

4.2.3 Interpreting Energy Pyramids

4.2.4 Efficiency of Energy Transfer

4.2.5 Limitations of Pyramids in Real Ecosystems

4.3 Environmental Change and Pollution

4.3.1 Natural vs Human-Induced Environmental Change

4.3.2 Air, Water, and Soil Pollution

4.3.3 Global Warming and Climate Change

4.3.4 Deforestation and Habitat Destruction

4.3.5 Pollution Effects on Food Chains and Webs

4.4 Biodiversity and Conservation

4.4.1 Definition and Importance of Biodiversity

4.4.2 Threats to Biodiversity

4.4.3 Endangered Species and Extinction

4.4.4 Methods of Conservation

4.4.5 Role of Humans in Protecting Biodiversity

4.5 Habitats and Adaptations

4.5.1 Definition of Habitat and Examples

4.5.2 Different Types of Habitats: Desert, Forest, Aquatic

4.5.3 Structural and Behavioral Adaptations

4.5.4 Adaptations for Survival in Extreme Environments

4.5.5 How Adaptations Increase Chances of Survival

4.6 Food Chains and Webs

4.6.1 Producers, Consumers, and Decomposers

4.6.2 Constructing and Interpreting Food Chains

4.6.3 Energy Flow Through Food Webs

4.6.4 Impact of Removing an Organism from a Food Web

4.6.5 Trophic Levels and Energy Transfer (Introductory)

5. Waves, Sound, and Light

5.1 Color and the Electromagnetic Spectrum

5.1.1 White Light and the Visible Spectrum

5.1.2 Dispersion of Light Through a Prism

5.1.3 Primary and Secondary Colors of Light

5.1.4 Overview of the Electromagnetic Spectrum

5.1.5 Uses of Different EM Waves (Introductory)

5.2 Sound Waves and Vibrations

5.2.1 How Sound is Produced and Transmitted

5.2.2 Vibrations in Solids, Liquids, and Gases

5.2.3 Representation of Sound as Longitudinal Waves

5.2.4 Speed of Sound in Different Media

5.2.5 Echoes and Reverberation

5.3 Pitch, Loudness, and Hearing

5.3.1 How Frequency Affects Pitch

5.3.2 How Amplitude Affects Loudness

5.3.3 The Human Ear and Hearing Range

5.3.4 Noise vs Music (Basic Concepts)

5.3.5 Protecting Hearing and Reducing Noise Pollution

5.4 Uses of Light and Sound in Technology

5.4.1 Applications of Light in Everyday Life

5.4.2 Fiber Optics and Communication

5.4.3 Ultrasound in Medicine and Industry

5.4.4 Radar and Sonar Basics

5.4.5 Light and Sound in Entertainment Systems

5.5 Properties of Waves

5.5.1 Definition of a Wave and Wave Types

5.5.2 Transverse vs Longitudinal Waves

5.5.3 Key Terms: Wavelength, Frequency, Amplitude, Speed

5.5.4 Measuring and Calculating Wave Speed

5.5.5 Wave Behavior: Reflection, Refraction, and Diffraction

5.6 Reflection and Refraction of Light

5.6.1 Laws of Reflection and Ray Diagrams

5.6.2 Plane Mirrors and Image Properties

5.6.3 Refraction Through Glass and Water

5.6.4 Why Objects Appear Bent in Water

5.6.5 Applications of Reflection and Refraction in Technology

6. Earth and Space Science

6.1 Weathering and Erosion

6.1.1 Definition and Types of Weathering

6.1.2 Processes of Erosion by Wind, Water, Ice

6.1.3 Soil Formation and Composition

6.1.4 Human Impacts on Erosion and Soil Loss

6.1.5 Prevention and Control of Erosion

6.2 The Solar System

6.2.1 Planets, Moons, and Other Celestial Bodies

6.2.2 Structure and Order of the Solar System

6.2.3 Movements of Planets Around the Sun

6.2.4 Asteroids, Comets, and Meteoroids

6.2.5 Historical Models of the Solar System

6.3 Phases of the Moon and Eclipses

6.3.1 Lunar Phases and Their Cycle

6.3.2 Why the Moon Changes Appearance

6.3.3 Solar and Lunar Eclipses

6.3.4 Tides and Moon’s Gravitational Effects (Introductory)

6.3.5 Viewing Moon Phases from Earth

6.4 Seasons and the Earth’s Tilt

6.4.1 Earth’s Rotation and Revolution

6.4.2 Why We Have Seasons

6.4.3 Effect of Tilt and Orbit on Day Length

6.4.4 Solstices and Equinoxes

6.4.5 Climatic Differences Due to Earth’s Movement

6.5 Structure of the Earth

6.5.1 Layers of the Earth: Crust, Mantle, Core

6.5.2 Properties and Composition of Each Layer

6.5.3 Tectonic Plates and Plate Boundaries (Introductory)

6.5.4 How Earth’s Structure Affects Landforms

6.5.5 Volcanoes and Earthquakes (Introductory)

6.6 Rocks and the Rock Cycle

6.6.1 Types of Rocks: Igneous, Sedimentary, Metamorphic

6.6.2 How Each Type of Rock Forms

6.6.3 The Rock Cycle Diagram

6.6.4 Physical and Chemical Properties of Rocks

6.6.5 Uses of Rocks and Minerals in Everyday Life

7. Electricity and Magnetism

7.1 Series and Parallel Circuits

7.1.1 Difference Between Series and Parallel Circuits

7.1.2 Current and Voltage in Series Circuits

7.1.3 Current and Voltage in Parallel Circuits

7.1.4 Advantages and Disadvantages of Each Type

7.1.5 Real-Life Applications: Home and School Circuits

7.2 Conductors and Insulators

7.2.1 Materials That Conduct Electricity

7.2.2 Good Conductors vs Poor Conductors

7.2.3 Uses of Conductors and Insulators

7.2.4 Testing Materials for Conductivity

7.2.5 Electrical Safety and Insulation

7.3 Magnets and Magnetic Fields

7.3.1 Properties of Magnets and Magnetic Materials

7.3.2 Magnetic Poles and Their Interaction

7.3.3 Drawing Magnetic Field Lines

7.3.4 Earth’s Magnetic Field (Introductory)

7.3.5 Temporary vs Permanent Magnets

7.4 Electromagnets and Their Applications

7.4.1 Making an Electromagnet

7.4.2 Factors Affecting Electromagnet Strength

7.4.3 Uses of Electromagnets in Daily Life

7.4.4 Magnetic Relays and Electromagnetic Devices

7.4.5 Comparing Magnets and Electromagnets

7.5 Static and Current Electricity

7.5.1 Definition of Static Electricity

7.5.2 Charging by Friction, Conduction, and Induction

7.5.3 Attraction and Repulsion of Charges

7.5.4 Definition and Flow of Electric Current

7.5.5 Comparing Static and Current Electricity

7.6 Electrical Circuits and Symbols

7.6.1 Components of a Simple Circuit

7.6.2 Circuit Symbols and Diagrams

7.6.3 Building and Testing Simple Circuits

7.6.4 Measuring Current and Voltage

7.6.5 Open and Closed Circuits

8. Forces and Motion

8.1 Friction, Air Resistance, and Drag

8.1.1 How Friction Affects Motion

8.1.2 Advantages and Disadvantages of Friction

8.1.3 Reducing Friction in Machines

8.1.4 Factors Affecting Air and Water Resistance

8.1.5 Streamlining and Surface Area Effects

8.2 Motion Graphs (Distance-Time)

8.2.1 Plotting and Interpreting Distance-Time Graphs

8.2.2 Constant Speed vs Changing Speed

8.2.3 Understanding Slope as Speed

8.2.4 Drawing Graphs from Descriptions

8.2.5 Matching Graphs to Real-World Scenarios

8.3 Speed, Velocity, and Acceleration

8.3.1 Calculating Speed = Distance ÷ Time

8.3.2 Difference Between Speed and Velocity

8.3.3 Understanding Acceleration (Introductory)

8.3.4 Using Units Correctly in Calculations

8.3.5 Solving Word Problems with Speed and Time

8.4 Force Diagrams and Net Force

8.4.1 Drawing and Labeling Force Diagrams

8.4.2 Calculating Net Force on an Object

8.4.3 Determining Direction of Motion

8.4.4 Free-Body Diagrams (Introductory)

8.4.5 Effect of Net Force on Acceleration and Speed

8.5 Types of Forces

8.5.1 Contact and Non-Contact Forces

8.5.2 Gravitational, Magnetic, and Electrostatic Forces

8.5.3 Friction and Air Resistance

8.5.4 Applied Force, Normal Force, and Tension

8.5.5 Identifying Forces in Everyday Situations

8.6 Balanced and Unbalanced Forces

8.6.1 Definition and Effects of Balanced Forces

8.6.2 Definition and Effects of Unbalanced Forces

8.6.3 Predicting Motion with Force Diagrams

8.6.4 Force Arrows and Vector Representation

8.6.5 Equilibrium and Motion Analysis

9. Energy Forms and Transfer

9.1 Conservation of Energy

9.1.1 Law of Conservation of Energy

9.1.2 Closed Systems and Energy Accounting

9.1.3 Explaining Why Energy is Never Lost, Only Transferred

9.1.4 Examples in Pendulums and Roller Coasters

9.1.5 Designing Simple Energy Investigations

9.2 Heat Transfer: Conduction, Convection, Radiation

9.2.1 Definition and Examples of Conduction

9.2.2 Definition and Examples of Convection

9.2.3 Definition and Examples of Radiation

9.2.4 Comparing the Three Modes of Heat Transfer

9.2.5 Real-Life Applications of Heat Transfer

9.3 Renewable and Non-Renewable Resources

9.3.1 Definition of Renewable Resources

9.3.2 Definition of Non-Renewable Resources

9.3.3 Fossil Fuels and Their Environmental Impact

9.3.4 Solar, Wind, and Hydro Energy Basics

9.3.5 Comparing Energy Resources for Sustainability

9.4 Energy Efficiency and Real-Life Use

9.4.1 Definition of Energy Efficiency

9.4.2 Calculating Efficiency (%)

9.4.3 Improving Energy Efficiency at Home and School

9.4.4 Energy Labels and Appliance Ratings

9.4.5 Evaluating Trade-Offs Between Efficiency and Cost

9.5 Forms of Energy

9.5.1 Definition and Examples of Different Energy Types

9.5.2 Kinetic and Potential Energy

9.5.3 Thermal, Chemical, Electrical, Light, and Sound Energy

9.5.4 Renewable and Non-Renewable Energy Sources

9.5.5 Energy in Daily Life Applications

9.6 Energy Transformations

9.6.1 Energy Conversion from One Form to Another

9.6.2 Energy Changes in Everyday Devices

9.6.3 Useful vs Wasted Energy

9.6.4 Energy Flow Diagrams and Sankey Diagrams (Introductory)

9.6.5 Examples: Light Bulb, Toaster, Car Engine

10. Chemical Reactions and the Periodic Table

10.1 Metals and Non-Metals

10.1.1 Properties and Uses of Metals

10.1.2 Properties and Uses of Non-Metals

10.1.3 Reactions of Metals with Acids

10.1.4 Formation of Metal Oxides

10.1.5 Corrosion and Its Prevention

10.2 The Periodic Table (Introductory)

10.2.1 Structure and Layout of the Periodic Table

10.2.2 Groups and Periods Explained

10.2.3 Metals, Non-Metals, and Metalloids

10.2.4 Trends in Group 1 and Group 7 Elements

10.2.5 Using the Periodic Table for Prediction

10.3 Reactivity and Chemical Properties

10.3.1 Definition of Reactivity

10.3.2 Reactivity Series of Metals

10.3.3 Displacement Reactions Between Metals

10.3.4 Reactions of Metals with Water and Steam

10.3.5 Comparing Reactivity Using Experiments

10.4 Everyday Chemical Changes

10.4.1 Chemical Reactions in Cooking

10.4.2 Photosynthesis and Respiration (Simplified)

10.4.3 Fireworks and Explosions

10.4.4 Rusting and Preventive Measures

10.4.5 Chemistry in Cleaning Products

10.5 Types of Chemical Reactions

10.5.1 Combustion and Burning Reactions

10.5.2 Oxidation and Rusting

10.5.3 Neutralization and Acid–Base Reactions

10.5.4 Thermal Decomposition (Introductory)

10.5.5 Simple Displacement Reactions

10.6 Signs of a Chemical Change

10.6.1 Colour Change and Gas Formation

10.6.2 Temperature and Light Change

10.6.3 Formation of Precipitate

10.6.4 Irreversibility of Chemical Reactions

10.6.5 Comparing Physical and Chemical Changes

11. Scientific Skills & Inquiry

11.1 Using Scientific Equipment Safely

11.1.1 Laboratory Safety Rules and Symbols

11.1.2 Handling Glassware, Chemicals, and Heat Sources

11.1.3 Wearing and Using Protective Gear

11.1.4 Emergency Procedures and First Aid in Lab

11.1.5 Disposing Materials and Cleaning Up Safely

11.2 Variables and Fair Testing

11.2.1 Types of Variables: Independent, Dependent, Controlled

11.2.2 Setting Up Fair Tests with One Variable

11.2.3 Why Control Variables Matter

11.2.4 Examples of Controlled Experiments

11.2.5 Evaluating the Fairness of an Investigation

11.3 Data Collection, Graphs, and Interpretation

11.3.1 Collecting Accurate and Reliable Data

11.3.2 Types of Graphs: Bar, Line, Pie

11.3.3 Plotting Data Points and Drawing Best Fit Lines

11.3.4 Reading and Interpreting Graphs

11.3.5 Identifying Trends, Anomalies, and Patterns

11.4 Drawing Conclusions and Evaluating Evidence

11.4.1 Making Conclusions Based on Data

11.4.2 Supporting Claims with Evidence

11.4.3 Identifying Errors and Limitations

11.4.4 Suggesting Improvements to Experiments

11.4.5 Reflecting on Reliability and Validity

11.5 Scientific Method and Experimental Design

11.5.1 Steps of the Scientific Method

11.5.2 Forming Testable Hypotheses

11.5.3 Designing Fair Experiments

11.5.4 Importance of Repeatability and Replication

11.5.5 Identifying and Controlling Variables

11.6 Observation, Measurement, and Recording

11.6.1 Qualitative vs Quantitative Observations

11.6.2 Measuring Length, Mass, Volume, and Temperature

11.6.3 Using SI Units and Unit Conversions

11.6.4 Recording Data in Tables and Logs

11.6.5 Using Tools Like Rulers, Balances, and Thermometers

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Definition and Comparison of Physical and Chemical Changes

Introduction