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
🔹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 :-
🔹Fixed mass, volume and shape
🔹Inter-particle distances are least.
🔹High density and do not diffuse.
🔹Inter particle forces of attraction are strongest.
🔹Constituent particles are very closely packed.
✳️ LIQUID :-
🔹Not fixed shape but fixed volume and mass.
🔹Inter particle distances are larger than solid.
🔹Density is lower than solids and can diffuse.
🔹Inter particle forces of attraction are weaker than solids.
🔹Constituent particles are less closely packed.
✳️ GAS :-
🔹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) :-
🔹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) :-
🔹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.