Matter In Our Surrounding Class 9th | Ncert Notes

Matter In Our Surrounding Class 9th | Ncert Notes

Introduction:

Matter In Our Surrounding: This topic brings you CBSE Class 9 science notes on chapter 1 'Matter in our surroundings' . This chapter notes prepared by Devkant chem classes and cover every important topic from the chapter.In between these notes,i will provide you most important questions.These questions definitely will help you for exam.And get hold on the subject.

Topic In this Chapter are Required:

● Introduction
● Physical nature of matter
● Diffusion
● Characteristics particles of nature

     ➤ Particles of matter have space between them

     ➤ particles of matter attract each other because of the force of attraction 

  ● States of matter

     ➤ Solid-state
     ➤ Liquid state
     ➤ Gaseous state

  ● Change of state of matter
  ● Effect of temperature

     ➤ Latent heat
     ➤ Latent heat of  fusion
     ➤ Latent heat of vaporization

  ● Effect of change in pressure
  ● Evaporation 

     ➤  Factor affecting the rate of evaporation

     ➤  Evaporation causes cooling

  ● Plasma
  ● Bose-Einstein condensate 

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Intro Of Chapter Matter In Our Surroundings:

➡ As we look at our surroundings, we see a large variety of things with different shapes, sizes and textures. Everything in this universe is made up of material which scientists have named "matter".

you can see many things around you such as plants, animals, water, air, tables, chair, and computers. They look different from each other but they have two things in common.

    ⚫ They take up space, The amount of space each takes up is called its volume. The volume of a 

          the bus is more than the volume of a car.

    ⚫ They have weight. An elephant has more weight than a cat.

All things that take up space and have weight are called matter. 

➡  Since early times human beings have been trying to understand their nature. Early Indian philosopher classified matter into five basic elements.The  "Punch Tattva"-air, earth, fire, sky and water. According to them everything, living as well as non-living things are made of these elements.

➡ Nowadays, scientists evolved into types of classification of matter -Physical properties and chemical nature.  

PHYSICAL NATURE OF MATTER  

➡ The matter is made up of particles. All matter constitute of very small particles.. These small particles are called atoms.

➡ These particles of matter are too small so they can't be seen by naked eyes or simple microscope.
➡ Particles of matter are continuously moving as they possess kinetic energy, with the increase of temperature kinetic energy of particles also increases so particles move faster. 

DIFFUSION:

➡The mixing and spreading out of a substance with another substance due to the movement or motion of its particles is called diffusion.

CHARACTERISTIC PARTICLES OF NATURE:

⚫ Particles of matter have space between them

➡ Gas can be compressed a lot because of the space between their particles.
➡ When sugar is dissolved in water, the particles of sugar disappear in water. This happens because particles of sugar get adjusted in the space between the particles of water. Additionally, you will notice that there is no risk of water level takes place when one or two teaspoons of sugar are added in a glass of water, this is because sugar particles get adjusted in the space between the particles of water and no rise in the water level comes in the result.

⚫ Particles of matter attract to each other because of the force of attraction   

➡ Force of attraction between the particles of matter keeps the particles bonded together. The force of attraction between the particles of solid is greatest, between particles of liquid is moderate and between particles of gas is lowest.
➡  Because of the lowest force of attraction between the particles of gas we can move our hand through the air easily. To move our hand in liquid, such as water, we have to apply some force, but from a solid such as wood, we can't our hand.
➡ This is because the force of attraction between the particles of gas is almost negligible, in liquid the forces of attraction is moderate but it is greatest in solid.
➡ The force of attraction between participles of solid, liquid and gas can be arranged in decreasing order as follows:-
                                       SOLID>LIQUID>GAS>    

STATES OF MATTER:

Matter around you either solid, liquid or gas. A brick is a solid, water is a liquid,air is a gas. These are the three states of matter. 


SOLID

➡ If you move a stone from one place to another, it does not change

Molecules in a solid are closely packed
together

its shape or space it occupies. This is because the molecules in a solid are packed very close together. They are strongly attracted to each other and can't move around much. That is why solids do not easily change their shape.

Thus, solid has a definite shape and volume. 





LIQUID

➡ Water in a jug takes the shape of the jug. If you pour this water into a bowl, it will take the shape of the bowl. If you pour the water on the floor, it will flow.

A liquid takes the shape of the container in which it is kept.

But the amount of space a liquid occupies (that is, its volume) remains the same no matter where it is poured.

Thus, Liquid can flow, they have a definite volume but no definite shape.

A liquid has no definite 
shape

Gases

Gases easily change their shape and volume. If you blow air in the balloon, it takes the shape of the balloon. It takes up less space in the balloon than it did outside.

similarly, air-filled in a cycle.

➡similarly, air-filled in a cycle or car tyres take much less space than it does outside. This causes the tyres to become harder.

                                     

Molecules in gas far from

each other

CHANGE OF STATE OF MATTER

➡ The phenomenon of change from one state of matter to another, and then back to their own state(original state) is called the interconversion of state of matter.

➡ Matter exists in three states

     Solid(as ice)⇆Liquid(as water)⇄Gas(as water vapor)

↪ if you go to forward and  heat solid then form a liquid, 
similarly, heat liquid then forms a gas.

↪ If you go to backward and coiling Gas then form Liquid, similarly, coiling liquid then form solid. 

EFFECT OF TEMPERATURE 

→ On increasing the temperature of solids, the kinetic energy of the particles increases which overcomes the forces of attraction between the particle that is why solid melts and converted to the liquid.
→ The temperature at which solid melts to become a liquid at the atmospheric pressure is called Melting point.
→ The melting point of ice is 273.16K

➡ The process of melting, that is, change of solid state into a liquid state is known as fusion.

LATENT HEAT
➡ The hidden heat which breaks the force of attraction between the molecules is known as the latent heat.

➡ since, the heat energy is hidden in the bulk of the matter, it is called latent heat.

LATENT HEAT OF FUSION

➡ The heat energy required to convert 1 kilogram of a solid into liquid at atmospheric pressure, at its melting point, is known as the latent heat of fusion.

➡ The temperature at which a liquid starts boiling, at atmospheric pressure, is called the boiling point.
➡  Boiling is a bulk phenomenon. Particles from the bulk of the liquid gain energy to change into the gaseous state.
Eg:- 
    ⚫ The boiling point of water is 100-degree centigrade (100c=273+100=373k)

LATENT HEAT OF VAPORIZATION

➡ The heat energy required to convert  1 kilogram of liquid into gas, at atmospheric pressure, at its boiling point, is known as the latent heat of vaporization. 

NOTE:- Water vapour at 373k has more energy than water at the same temperature because particles in steam have absorbed extra energy in the form of latent heat of vaporization. 

➡ The process, in which a gas on coiling, turns into a liquid at a specific temperature is called condensation or liquefaction.
formation of clouds is due to the condensation of water vapour from the earth's surface.

➡ The change of state of a substance directly from a solid to gas, without changing into the liquid state( or vice versa) is called sublimation.

➡  The temperature at which the state of a substance changes from a liquid to a solid-state is called the freezing point of that substance.

EFFECT OF CHANGE IN PRESSURE:

➡ Gas to liquid:- Gases can be liquefied by applying pressure and reducing the temperature. When high pressure is applied to a gas, it gets compressed and if the temperature is lowered, the gas is liquefied.
Solid carbon dioxide gets converted directly to gaseous state on the decrease of pressure to 1 atmosphere without coming into liquid state.this is the reason that solid carbon dioxide is also known as dry ice.

EVAPORATION:

➡ The process of conversion of a substance from the liquid state to the gaseous state at any temperature below its boiling point is called evaporation or vaporization. 

FACTOR AFFECTING THE RATE OF EVAPORATION:

➡ Surface area:-The  rate of evaporation increases on increasing the surface area of the liquid.
➡ Temperature:-The rate of evaporation increases with an increase in temperature. 
➡ Humidity:-Decreases in the humidity increases the rate of evaporation.
➡ Wind speed:-An increases in wind speed increases the rate of evaporation.

EVAPORATION CAUSES COOLING:

➡ During the process of evaporation, the particles of liquid absorb energy or latent heat of vaporization from the surrounding to get converted to the gaseous state. This absorption of energy from the surroundings make the surroundings cold.
Eg:-
       The perspiration or sweating on our body keeps the body temperature constant by taking away the extra heat from the body as the latent heat of vaporization. 

PLASMA:

➡It is a mixture of free electrons and ions. It occurs naturally in stars. inside the stars, the temperature is very high that atoms break up giving electrons and ions is called plasma.
Plasma can be made by passing electricity through gases at very low pressure taken in a glass tube.

Bose-Einstein condensate:

➡ Bose-Einstein condensate is obtained by cooling a gas of extremely low density to super low temperature.

  

SOME IMPORTANT QUANTITIES AND THEIR SI UNIT

Quantity                                             Unit                                                        Symbol

☞Temperature                               Kelvin                                                              K

☞Length                                  Meter                                                            m

☞Mass                                     kilogram                                                        kg

☞Weight                                  newton                                                          N

☞Volume                                 cubic meter                                                  m³

☞Density                                 kilogram per cubic meter                            kg/m3

☞Pressure                              pascal                                                              pa     

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