# NCERT Class 7 Science Chapter 5 Changes Around Us: Physical and Chemical: Summary, Key Concepts, Notes, and Diagrams | SwaVid Chapter 5, "Changes Around Us: Physical and Chemical", introduces students to the fascinating world of transformations that constantly occur in our dail... Canonical: https://swavid.com/science/class/7/chapter/changes-around-us-physical-and-chemical Source: https://swavid.com/science/class/7/chapter/changes-around-us-physical-and-chemical # Changes Around Us: Physical and Chemical ## Concepts in this chapter ## The ideas this chapter keeps returning to ## Where this chapter usually trips people up ## Find the gaps before this chapter finds them for you. ## Related chapters ### What are Changes? Chapter 5 · Class 7 Science Chapter 5, "Changes Around Us: Physical and Chemical", introduces students to the fascinating world of transformations that constantly occur in our daily lives. From the simple act of melting ice to the complex process of cooking food, everything involves some form of change. This chapter helps students classify these changes based on whether new substances are formed and if the change can be easily reversed, laying a fundamental groundwork for understanding matter and its interactions. Your study route Key topics Introduces the idea that everything around us is constantly undergoing some form of transformation, from natural processes to human activities. Example Growth of a plant, ripening of fruit, cooking food. Watch out Thinking all changes are complex or require human intervention. Introduces the idea that everything around us is constantly undergoing some form of transformation, from natural processes to human activities. Tap the card for an example Example Growth of a plant, ripening of fruit, cooking food. Why it matters Helps students observe and categorize phenomena in their environment, fostering scientific curiosity. Watch out Thinking all changes are complex or require human intervention. Ask at home Ask the child to list 3 changes they observed today and describe them simply. This chapter explores the two primary types of changes observed in our surroundings: physical and chemical changes. A physical change alters the physical properties of a substance, such as its shape, size, state, or appearance, but does not form any new substance. These changes are often reversible. Examples include melting of ice, dissolving sugar in water, or tearing paper. In contrast, a chemical change results in the formation of one or more new substances with different chemical properties. These changes are generally irreversible and often involve energy changes, such as the release or absorption of heat or light. Common indicators of chemical changes include changes in colour, production of gas, sound, or smell. Key examples discussed are the rusting of iron, the burning of magnesium ribbon, and the crystallization of substances like copper sulphate. Understanding these distinctions is crucial for comprehending how matter interacts and transforms. Chapter summary This chapter explores the two primary types of changes observed in our surroundings: physical and chemical changes. A physical change alters the physical properties of a substance, such as its shape, size, state, or appearance, but does not form any new substance. These changes are often reversible. Examples include melting of ice, dissolving sugar in water, or tearing paper. In contrast, a chemical change results in the formation of one or more new substances with different chemical properties. These changes are generally irreversible and often involve energy changes, such as the release or absorption of heat or light. Common indicators of chemical changes include changes in colour, production of gas, sound, or smell. Key examples discussed are the rusting of iron, the burning of magnesium ribbon, and the crystallization of substances like copper sulphate. Understanding these distinctions is crucial for comprehending how matter interacts and transforms. What you should learn Keep these close Changes are broadly classified into physical and chemical changes. Physical changes alter physical properties but do not form new substances. Physical changes are generally reversible, though not always easily. Chemical changes form new substances with different properties. Chemical changes are generally irreversible. Indicators of chemical changes include heat, light, sound, gas formation, colour change, or smell change. Rusting is a chemical change where iron reacts with oxygen and water. Rusting can be prevented by painting, oiling, greasing, or galvanization. Galvanization is coating iron with a protective layer of zinc. Crystallization is a physical change used to obtain pure substances in crystal form. Burning is always a chemical change as new substances (ash, gases) are formed. Photosynthesis is a chemical change where plants convert carbon dioxide and water into glucose and oxygen. Common confusions It is easy to think All physical changes are reversible. The clearer idea While many physical changes are reversible (e.g., melting ice), some are not easily reversible (e.g., tearing paper, cutting wood). The key characteristic of a physical change is that no new substance is formed, regardless of reversibility. It is easy to think Dissolving a substance (like sugar in water) is a chemical change because the sugar 'disappears'. The clearer idea Dissolving is a physical change. The sugar molecules are still present, just dispersed evenly in the water. You can recover the sugar by evaporating the water, proving no new substance was formed. It is easy to think A change involving heat is always a chemical change. The clearer idea Heat can be involved in both physical and chemical changes. For example, heating water to boil it is a physical change, while heating food to cook it is a chemical change. The formation of a new substance is the key differentiator for chemical changes. It is easy to think Rust is just dirt that can be wiped off. The clearer idea Rust is a new chemical substance (iron oxide) formed from the reaction of iron with oxygen and water. It is not merely a surface coating but a transformation of the iron itself, which weakens the metal and cannot be simply wiped away. Before you push ahead Most stuck chapters trace back to one earlier idea. Check the prerequisites first, or let SwaVid adapt this chapter to the way your child learns. Keep exploring Class 7 Source - Differentiate between physical and chemical changes based on observable characteristics. - Identify examples of physical and chemical changes in everyday life. - Explain the concept of reversibility and irreversibility in the context of changes. - Describe the process of rusting and methods to prevent it. - Understand the process of crystallization as a physical change. - Differentiate between physical and chemical changes based on observable characteristics. - Identify examples of physical and chemical changes in everyday life. - Explain the concept of reversibility and irreversibility in the context of changes. - Describe the process of rusting and methods to prevent it. - Understand the process of crystallization as a physical change. - NCERT Class 7 Science textbook: Curiosity : Chapter 5: Changes Around Us: Physical and Chemical ## Key Links - [NCERT Science](https://swavid.com/science) - [Class 7](https://swavid.com/science/class/7) - [Start with concepts](https://swavid.com/science/class/7/chapter/changes-around-us-physical-and-chemical) - [Check a prerequisite](https://swavid.com/learning-debt-identifier) - [Concepts](https://swavid.com/science/class/7/chapter/changes-around-us-physical-and-chemical) - [Practice](https://swavid.com/science/class/7/chapter/changes-around-us-physical-and-chemical/practice-questions) - [NCERT Solutions](https://swavid.com/science/class/7/chapter/changes-around-us-physical-and-chemical/ncert-solutions) - [Find the gaps before this chapter](https://swavid.com/learning-debt-identifier) - [Learn this chapter adapted to you](https://swavid.com/learning-style-test) - [Previous chapter 4 . 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