9th Class Science Notes in English chapter 1 Matter in Our Surroundings

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 9th Class Science Notes in English chapter 1 Matter in Our Surroundings


CBSE Revision Notes for CBSE Class 09 Science Matter in Our Surrounding Definition of matter; solid, liquid and gas; characteristics - shape, volume, density; change of state-melting (absorption of heat), freezing, evaporation (cooling by evaporation), condensation, sublimation. Nature of matter : Elements, compounds and mixtures. Heterogenous and homogenous mixtures, colloids and suspensions.


Class 9th Science chapter 1 Matter in Our Surroundings Notes in English.  



 📚 Chapter - 1 📚 

👉 Matter in Our  Surroundings 👈


✔ Topics in the Chapter

🔹Matter

🔹Particle nature of matter. 

🔹All five states of matter & their behaviour 

🔹Enter conversion of states of matter 

🔹Evaporation & Boiling

🔹Conversion between Kelvin scale & Celsius scale


✳️ Matter :-    


🔹Anything that occupies space and has mass and is felt by senses is called matter. 

🔹According to indian ancient philosphor, matter is the form of five basic elements (the Panchtatva) - air , earth,fire , sky and water. 


✳️ Characteristics of Particles of Matter :-    


🔹 Made of tiny particles. 

🔹Vacant spaces exist between particles. 

🔹Particles are in continuous motion. 

🔹Particles are held together by forces of attraction. 


✳️ States of Matter Basis of Classification of Types :-   


🔹Based upon particle arrangement 

🔹Based upon energy of particles 

🔹Based upon distance between particles 


✳️ Five states of matter :-   


🔹Solid 

🔹Liquid 

🔹Gas 

🔹Plasma 

🔹Bose-Einstein condensate


✳️ SOLID :- 


9th Class Science Notes in English chapter 1 Matter in Our Surroundings


🔹Fixed mass, volume and shape 

🔹Inter-particle distances are least. 

🔹Incompressible. 

🔹High density and do not diffuse. 

🔹Inter particle forces of attraction are strongest. 

🔹Constituent particles are very closely packed. 


✳️ LIQUID  :-


9th Class Science Notes in English chapter 1 Matter in Our Surroundings

🔹Not fixed shape but fixed volume and mass. 

🔹Inter particle distances are larger than solid. 

🔹Almost incompressible. 

🔹Density is lower than solids and can diffuse. 

🔹Inter particle forces of attraction are weaker than solids. 

🔹Constituent particles are less closely packed.


✳️  GAS :- 

9th Class Science Notes in English chapter 1 Matter in Our Surroundings



🔹Neither fixed shape nor fixed volume. 

🔹Inter particle distances are largest. Highly compressible. 

🔹Density is least and diffuse. 

🔹Inter particle forces of attraction are weakest. 

🔹Constituent particles are free to move about. 


✳️ PLASMA (NON-EVALUATIVE) :-


9th Class Science Notes in English chapter 1 Matter in Our Surroundings


🔹A plasma is an ionized gas. 

🔹A plasma is a very good conductor of electricity and is affected by magnetic fields. 

🔹Plasma, like gases have an indefinite shape and an indefinite volume. Ex. lonized gas 


✳️ BOSE-EINSTEIN CONDENSATE (non - evaluative)  :-


9th Class Science Notes in English chapter 1 Matter in Our Surroundings


🔹A BEC is a state of matter that can arise at very low temperatures. 

🔹The scientists who worked with the Bose- Einstein condensate received a Nobel Prize for their work in 1995. 

🔹The BEC is all about molecules that are really close to each other (even closer than atoms in a solid).


✳️ Macroscopic Explanation for Properties of solids :-   


🔹Solids have a definite shape and a definite volume because the particles are locked into place. 

🔹Solids do not flow easily because the particles cannot move/slide past one another. 

🔹Solids are not easily compressible because there is little free space between particles. 


✳️ Microscopic Explanation for Properties of Liquids :-  


🔹Liquids are not easily compressible and have a definite volume because there is little free space between particles. 

🔹Liquids flow easily because the particles can move/slide past one another. 

🔹Liquids flow easily because the particles can move/slide past one another. 


✳️ Microscopic Explanation for Properties of Gases :-    


🔹Gases are easily cor there is a great deal of free space between particles 

🔹Gases flow very easily because the particles randomly move past one another. 

🔹Gases have an indefinite shape and an indefinite volume because the particles can move past one another (non -evaluative). 


✳️ Microscopic Explanation for Properties of Plasmas :-    


🔹Plasmas have an indefinite shape and an indefinite volume because the particles can move past one another. 

🔹Plasmas are easily compressible because there is a great deal of free space between particles. 

🔹Plasmas are good conductors of electricity &are affected by magnetic fields because they are composed of lens. 


✳️ Microscopic Explanation for Properties of BEC :-    


🔹Particles are less energetic than solids because Exist at very low temperature. 

🔹Particles are literally indistinguishable because they are locked into same space. 

🔹BEC shows super fluidity because Particles can flow without friction.


✳️ Interchange in states of matter :-    


🔷 Water can exist in three states of matter - 


🔹Solid, as ice, 

🔹Liquid, as the familiar water, and 

🔹Gas, as water vapour.


   ♦️ Sublimation :-  The changing of solid directly into vapours on heating & vapours into solid on cooling. Ex. Ammonium chloride, camphor & iodine.


✳️ Effect of change in temperature  :-


The temperature effect on heating a solid varies depending on the nature of the solid & the conditions required in bringing the change. 


🔹On increasing the temperature of solids, the kinetic energy of the particles increases which overcomes the forces of attraction between the particles thereby solid melts and is converted to a liquid. 

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

🔹The melting point of ice is 273.16 K. 

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


✳️ Effect of Change of Pressure  :-


🔹 Increasing or decreasing the pressure can change the state of matter. Applying pressure and reducing temperature can liquefy gases. 

🔹Solid carbon dioxide (CO2) is stored under high pressure. Solid CO2 gets converted directly to gaseous state on 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. 


✳️ Latent Heat :- 


🔹The hidden heat which breaks the force of attraction between the molecules during change of state. Fusion Heat energy required to change 1kg of solid into liquid. 


🔹Vaporisation Heat energy required to change 1kg of liquid to gas at atmospheric pressure at its boiling point. 


🔹Thus, we can say that pressure and temperature determine the state of a substance, whether it will be solid, liquid or gas.


✳️ Evaporation & Boiling :-


🔹Particles of matter are always moving and are never at rest. 

🔹At a given temperature in any gas, liquid or solid, there are particles with different amounts of kinetic energy. 

🔹In the case of liquids, a small fraction of particles at the surface, having higher kinetic energy, is able to break away from the forces of attraction of other particles and gets converted into vapour. 

🔹This phenomenon of change of a liquid into vapours at any temperature below its boiling point is called evaporation. 


✳️ Factors Affecting Evaporation :-


🔹The rate of evaporation increases with an increase of surface area. 

🔹With the increase of temperature, more number of particles get enough kinetic energy to go into the vapour state. 

🔹Humidity is the amount of water vapour present in air. The air around us cannot hold more than a definite amount of water vapour at a given temperature. If the amount of water in air is already high, the rate of evaporation decreases. 

🔹Wind speed : the higher the wind speed, the more evaporation. 


✳️ Evaporation cause cooling :- 


🔹The particles of liquid absorb energy from the surrounding to regain the energy lost during evaporation, 


✳️ Evaporation Vs Boiling  :-


🔹Boiling is a bulk phenomenon. Particles from the bulk (whole) of the liquid change into vapour state. 

🔹Evaporation is a surface phenomenon. Particles from the surface gain enough energy to overcome the forces of attraction present in the liquid and change into the vapour state. 


✳️ Kelvin & Celsius Scale :-  


🔹Kelvin is the Sl unit of temperature, 0°C = 273.16 K we take 0°C = 273 K. 

🔹Sl unit of temperature is Kelvin. T (K) = T('C) + 273 

🔹Kelvin scale of temperature has always positive sign , hence regarded as better scale than Celsius. 

🔹Atmosphere (atm) is a unit of measuring pressure exerted by a gas. The SI unit of pressure is Pascal (Pa):

🔹1 atmosphere = 1.01 x (10 to the power 5) Pa. The pressure of air in atmosphere is called atmospheric pressure. The atmospheric pressure at sea level is 1 atmosphere, and is taken as the normal atmospheric pressure. 

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