Matter in Our Surroundings | CBSE Class 9 | Future Classes
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Exploring the Wonders of Nature: A Guide to CBSE Class 9 Science - Matter in Our Surroundings

CBSE Class 9 Science Notes can help students gain a better understanding of the matter that is all around us. Matter can be found in all forms and states, and it is important for students to understand the physical and chemical properties of matter. The CBSE Class 9 Science Notes provide students with a comprehensive overview of topics such as elements, compounds, mixtures, properties of matter, states of matter, and more. With these notes, students will be able to better comprehend and apply the concepts learned in class.

The CBSE Class 9 Science curriculum covers the topic of Matter in Our Surroundings in great detail. To help students learn and understand this topic, we have made available a PDF download that covers all the important aspects of Matter in Our Surroundings. This PDF download includes detailed explanations of topics such as states of matter, physical and chemical changes, and conservation of matter. With this PDF download, students can easily review the material and gain a comprehensive understanding of the topic.

Matter in Our Surrounding

Matter

Everything in this universe is made up of material which scientists have named “matter”. The air we breathe, the food we eat, stones, clouds, stars, plants and animals, even a small drop of water or a particle of sand – everything is matter.

In other words, they have both mass and volume.

Physical Nature of Particles:

Matter is made up of particles. The particles of matter are very-very small.

Characteristics of Particles:

  1. Particles of matter are continuously moving

  2. Particles of matter have space between them.

States of Matter

Matter around us exists in three different states – solid, liquid and gas.

The solid state

Solid have a tendency to maintain their shape when subjected to outside force. Solid may break under force but it is difficult to change their shape, so they are rigid.

The liquid state

Liquids have no fixed shape but have a fixed volume. They take up the shape of the container in which they are kept. Liquids flow and change shape, so they are not rigid but can be called fluid.

The gases from the atmosphere diffuse and dissolve in water.

All living creatures need to breathe for survival. The aquatic animals can breathe under water due to the presence of dissolved oxygen in water.

The gaseous state

Gases are highly compressible as compared to solids and liquids. Example liquefied petroleum gas (LPG), oxygen cylinders, compressed natural gas (CNG).

Due to high speed of particles and large apace between them, gases show the property of diffusing very fast into other gases.

Change of State of Matter:

we can change one state of matter to another state by changing temperature.

Melting point

The temperature at which a solid melt to become a liquid at the atmospheric pressure is called its melting point.

  • The melting point of ice is 273.16 K.

  • Change of solid state into liquid state is also known as fusion.

Kelvin is the SI unit of temperature, 0 C = 273.16 K for convenience, we take 0 C = 273 K after rounding off the decimal.

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Latent heat

Heat absorbed or released by a substance during a change in its physical state that occurs without changing its temperature.

  • Latent Heat of Fusion: The amount of heat required to change 1 kg solid to its liquid state (at its melting point) at atmospheric pressure.

Boiling point

The temperature at which a liquid starts boiling at the atmospheric pressure is known as its boiling point.

  • Latent Heat of Vaporization: The amount of heat required to change 1 kg liquid to its gaseous state (at its boiling point) at atmospheric pressure.

  • During boiling the temperature of water does not rise even though heat is being supplied continuously as this heat of vaporization is used up to over the forces of attraction between water particles.

Freezing

the temperature at which a liquid freeze to become a solid at atmospheric pressure is known as the freezing point.

Sublimation

A change of state directly from solid to gas without changing into liquid state (or vice versa) is called sublimation.

Effect of Change of Pressure:

If we compress a gas in a cylinder, the distance between the particles of gas is reduced and finally gas is liquefied on lowering temperature.

  • By applying high pressure, the particles of a gas can be brought close together.

  • Solid carbon dioxide (dry ice) is changed into carbon dioxide gas directly without changing into liquid when pressure is reduced to 1 atmospheric pressure.

Thus, states of matter i.e., solid, liquid, gas are determined by temperature & pressure.

matter in our surrounding

Evaporation:

A surface phenomenon in which liquid changes into vapors at any temperature below its boiling point is called evaporation.

Particles on the surface of a liquid have higher kinetic energy than others, so they break the forces of attraction between the particles & escape from the surface of liquid in the form of vapors.

Factors affecting evaporation:

  1. Exposed surface area: On increasing surface area of liquid, rate of evaporation increases.

  2. Increase in temperature: Increases kinetic energy of particles, rate of evaporation increases.

  3. Humidity: When the humidity of air is low, evaporation rate is increased. More humidity, less evaporation.

  4. Wind: When wind speed increases, rate of evaporation also increases.

Evaporation always causes cooling:

  1. The cooling caused by evaporation is based on the fact that when a liquid evaporates, it takes latent heat of vaporization from surroundings which on losing heat get cooled.

The CBSE Class 9 Science curriculum covers the topic of Matter in Our Surroundings in great detail. To help students learn and understand this topic, we have made available a PDF download that covers all the important aspects of Matter in Our Surroundings. This PDF download includes detailed explanations of topics such as states of matter, physical and chemical changes, and conservation of matter. With this PDF download, students can easily review the material and gain a comprehensive understanding of the topic.

Matter in Our Surrounding - Chapter 1, CBSE Class 10

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