Welcome to the fascinating world of matter! The chapter “Matter in Our Surroundings” is the first step in understanding the fundamental building blocks of the universe. Everything around us, from the air we breathe to the food we eat, is made up of matter.
Matter in Our Surroundings Key Concepts
To help students grasp the key concepts of this chapter, we have created a set of flashcards. Flashcards are an excellent tool for quick revision and self-assessment. Each flashcard contains a term or concept on the front side and its definition or explanation on the back side.
Matter in Our Surroundings Important Terms
| Key Terms | Definition |
|---|---|
| Matter | Everything in the universe that occupies space and has mass. It is made up of particles. |
| Panch Tatva | Ancient Indian classification of matter into five basic elements: air, earth, fire, sky, and water. |
| Physical Nature of Matter | Matter is made up of tiny particles that have space between them, are continuously moving, and attract each other. |
| Particles of Matter | Tiny units that make up matter. They have space between them, are in constant motion, and attract each other. |
| Diffusion | The intermixing of particles of two different types of matter on their own, due to the movement of particles. |
| Kinetic Energy | The energy possessed by particles due to their motion. It increases with temperature. |
| States of Matter | Matter exists in three states: solid, liquid, and gas, depending on the arrangement and movement of particles. |
| Solid State | A state of matter with a definite shape, distinct boundaries, and fixed volume. Particles are closely packed and have strong forces of attraction. |
| Liquid State | A state of matter with no fixed shape but a fixed volume. Liquids take the shape of the container and can flow. Particles have more space and less attraction than solids. |
| Gaseous State | A state of matter with no fixed shape or volume. Particles move randomly at high speed and have weak forces of attraction. |
| Compressibility | The ability of matter to be compressed. Gases are highly compressible, while solids and liquids are not. |
| Melting Point | The temperature at which a solid melts to become a liquid at atmospheric pressure. |
| Boiling Point | The temperature at which a liquid starts boiling and changes into a gas at atmospheric pressure. |
| Latent Heat of Fusion | The amount of heat energy required to change 1 kg of a solid into a liquid at its melting point without changing its temperature. |
| Latent Heat of Vaporisation | The amount of heat energy required to change 1 kg of a liquid into a gas at its boiling point without changing its temperature. |
| Sublimation | The process by which a solid changes directly into a gas without passing through the liquid state. |
| Deposition | The process by which a gas changes directly into a solid without passing through the liquid state. |
| Evaporation | The process by which a liquid changes into a gas at any temperature below its boiling point. It is a surface phenomenon. |
| Factors Affecting Evaporation | Surface area, temperature, humidity, and wind speed affect the rate of evaporation. |
| Cooling Effect of Evaporation | Evaporation causes cooling because particles absorb energy from the surroundings to change into vapour, leaving the surroundings cooler. |
| Density | The mass per unit volume of a substance. It is calculated as density = mass/volume. |
| Atmospheric Pressure | The pressure exerted by the air in the atmosphere. At sea level, it is 1 atmosphere (atm). |
| Interconversion of States of Matter | The change of matter from one state to another (solid, liquid, gas) by changing temperature or pressure. |
| Rigidity | The property of solids to maintain their shape and resist deformation. |
| Fluidity | The ability of liquids and gases to flow and take the shape of their container. |
| Bulk Phenomenon | A phenomenon that occurs throughout the entire substance, such as boiling, where particles from the bulk of the liquid change into vapour. |
| Surface Phenomenon | A phenomenon that occurs only at the surface of a substance, such as evaporation, where particles at the surface gain energy and escape into the vapour state. |
| Humidity | The amount of water vapour present in the air. High humidity reduces the rate of evaporation. |
| Dry Ice | Solid carbon dioxide (CO₂) that sublimates directly into a gas without passing through the liquid state. |
| Kinetic Theory of Matter | The theory that explains the behavior of matter based on the movement of its particles. Particles in solids vibrate, in liquids slide past each other, and in gases move freely. |
| Pressure | The force exerted by gas particles per unit area on the walls of the container. It is measured in Pascals (Pa). |
| Temperature | A measure of the average kinetic energy of particles in a substance. It is measured in Kelvin (K) or Celsius (°C). |
| Compressed Natural Gas (CNG) | Natural gas that is compressed to a high pressure and used as fuel in vehicles. It is highly compressible. |
| Liquefied Petroleum Gas (LPG) | A flammable gas used as fuel in homes for cooking. It is stored in liquid form under high pressure. |
| Water Cycle | The continuous process of water evaporating, condensing, and precipitating, changing states between liquid, gas, and solid. |
| Condensation | The process by which a gas changes into a liquid when it loses energy. |
| Freezing Point | The temperature at which a liquid changes into a solid. For water, it is 0°C (273 K). |
| Heat Energy | The energy transferred between substances due to a temperature difference. It causes changes in the state of matter. |
| Pascal (Pa) | The SI unit of pressure. 1 atmosphere (atm) = 1.01 × 10⁵ Pa. |
| Kelvin (K) | The SI unit of temperature. 0°C = 273 K. |
| Cubic Metre (m³) | The SI unit of volume. 1 litre (L) = 1 dm³ = 1000 mL. |
| Kilogram (kg) | The SI unit of mass. |
- Grade Level: 9th Grade (CBSE, NCERT, and other state boards)
- Subject: Science (Chemistry)
- Chapter: 1 – Matter in Our Surroundings
- Check out Chapter 2 –
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