Materials: Properties and Changes PDF Study Guide G5

Unit 2 - Materials: Properties and Changes Understanding materials helps us understand how things are made and how they can change. Materials can change in many ways, and these changes can be physical or chemical. Physical changes affect the form of a material, but not its c...

Unit 2 - Materials: Properties and Changes Understanding materials helps us understand how things are made and how they can change. Materials can change in many ways, and these changes can be physical or chemical. Physical changes affect the form of a material, but not its chemical composition. Melting, cutting, and freezing are examples of physical changes. Chemical changes, on the other hand, happen when two or more substances form a new substance. Rusting, burning, and cooking are examples of chemical changes. These processes change a material into a completely new substance. Understanding material properties and changes helps scientists and engineers create new materials, and improve the ones we use every day. By knowing how materials behave, we can build stronger buildings, create safer vehicles, and develop better technology for the future. 1  Unit 2 - Materials: Properties and Changes 2.1 Properties of Substances Everything around us is made up of matter. So what is matter? According to scientists, matter is anything that has mass and takes up space (i.e., has volume). Matter is an interesting phenomenon because it can change from solid to liquid to gas. We call these the three states of matter. Materials are specific substances or combinations of substances, such as wood or marble. Substances, on the other hand, are chemical elements (such as gold or water) or chemical compounds, such as water or salt. Cambridge Primary Science Learner’s Book 6 - pages 35 - 41 Melting Point 2 The Difference Between Evaporation and Boiling 3 Melting and Freezing Evaporation and Condensation 4 From: Cambridge Learner’s Book 6, Hodder Education States of Matter 5  Unit 2 - Materials: Properties and Changes 2.2 Thermal and Electrical Conductors Thermal conductors are materials that allow heat to travel through them easily, such as metals like aluminium, copper, and steel. Materials that are poor conductors of heat are called insulators. These materials include non metals such as plastic, glass, rubber, and wood. Electrical conductors are substances or materials that allow electricity to flow through them. Most metals are good conductors of electricity, while non metals are not. Cambridge Primary Science Learner’s Book 6 - pages 42 - 48 Thermal Conductors 6 Electrical Conductors Difference Between Conductors and Insulators 7  Unit 2 - Materials: Properties and Changes 2.3 Reversible Changes When materials are heated or cooled, they may change their state: Solids that are heated enough may changed into liquid. Liquids that are cooled enough may change into solids. Liquids that are heated enough may change into gas. Gas that is cooled enough may change into liquid. Sometimes, the changes are reversible, which means that the material/substance can be changed back to its original state. However, sometimes changes cannot be reversed, and are permanent. Cambridge Primary Science Learner’s Book 6 - pages 49 - 55 Reversible and Irreversible Changes 8  Reversible Changes Irreversible Changes Dissolving 9 From: Cambridge Learner’s Book 6, Hodder Education  Unit 2 - Materials: Properties and Changes 2.4 Chemical Reactions A chemical reaction happens when two or more substances react to each other and form a new substance. The substances that react to each other are called reactants, and the new substance is called a product. You may think that chemical reactions only take place in labs. But that’s not true. Metal rusting, batteries producing electricity, and photosynthesis in plants are all examples of chemical reactions. Cambridge Primary Science Learner’s Book 6 - pages 56 - 62 10