Matter in Our Surrounding Chapter 1 Short Notes | Chapter 1 Science Notes | Class 9 Science Notes | Short Notes of Matter in Our Surrounding | Physicswallah.in

Matter in Our Surrounding Chapter 1 Short Notes | Chapter 1 Science Notes | Class 9 Science Notes | Short Notes of Matter in Our Surrounding | Physicswallah.in 

Matter in Our Surrounding Chapter 1 Short Notes | Chapter 1 Science Notes | Class 9 Science Notes | Short Notes of Matter in Our Surrounding | Physicswallah.in 

Introduction

Humans have been inquisitive about the character of their environment since antiquity. Early Indian thinkers categorised all materials into five basic components, called the "Panch Tatva": air, earth, fire, sky, and water. Their theory holds that everything in existence, whether alive or non-living, is made up of these components.

Scientists today categorise matter using two methods: its physical characteristics and chemical makeup.

The physical nature of matter is composed of small particles. Every material consists of tiny, atomic-sized components.

These particles are so tiny that even a basic microscope cannot see them, much less the human eye.

Kinetic energy The particles in matter are always in motion. The kinetic energy grows as the temperature does, which causes the particles to move quicker.

Brownian motion is the erratic, zigzag movement of small particles in a medium.

Diffusion: Diffusion is the natural process where particles from two distinct substances combine on their own. Higher temperatures for the compounds involved accelerate the rate of diffusion. Solids, liquids, and gases all undergo diffusion.

Properties of Matter Particles 

1. Particles Have Space Between Them
The significant distances between their particles allow gases to be readily compressed.

Adding sugar to water causes it to dissolve as the little sugar particles fill the voids between water molecules. Interestingly, the water level does not rise even after adding a teaspoon or two of sugar since the sugar particles fit into the spaces between the water molecules.

Particles draw one another.

A force of attraction binds the particles of matter together.

Its strength is strong in solids, moderate in liquids, and weakest in gases show how this force differs among several states of matter.

This clarifies why moving a hand through air is simple, but moving it through water calls for some effort, and passing a hand through a solid material like wood is impossible.

One can order the strength of attraction between the particles as follows:
Solids outshine liquids, which outshine gases.

Forms of Matter 

1. Solid State

In solids, the particles are closely packed, leaving very little space between them.

Strong attraction interactions between the particles maintain their fixed locations, hence providing solids a stiff structure.

Even under external pressure, solids keep their shape.

They are incompressible.

Low kinetic energy among solid particles causes an ordered arrangement. This is the reason solids possess a specific shape and volume.

2. Liquid State

In liquids, the particles have slightly more space between them than in solids, but far less than in gases.

Particles' attraction is strong enough to hold them together but not so strong as to hold them stationary in one location.

Liquids lack a defined form; rather, they assume the shape of the container into which they are poured.

They have adjusted their volume.

Liquid particles have more kinetic energy than solids, which causes a more chaotic arrangement.

Liquids are not readily compressible since the gaps between their particles are still somewhat tiny.

3. gaseous state

Compared to solids and liquids, particles in gases are significantly more separated, which makes their organization quite chaotic.

Gas particles' attraction is fragile, which lets them travel freely in all directions.

Their continual motion allows gases to mix freely with other gases.

The maximum kinetic energy belongs to gas particles, which causes them to travel quickly and press against the walls of their container.

Lacking a defined shape or volume, gases expand to fill any container.

Unlike liquids and solids, gases can be compressed quite a bit, which is why LPG (liquefied petroleum gas) and CNG (compressed natural gas) are kept in compressed form in cylinders.

Variations in the States of Matter

The interconversion of states of matter is the process of changing one form of matter into another and then back again.

Under varied temperature and pressure circumstances, matter can change between several states.

Water, for instance, can be in all three states:

Ice: Solid

Liquid: H₂O

Gas: vaporized water.

Temperature's Influence on States of Matter

A solid's temperature rise causes its particle kinetic energy to increase as well. Increased energy lets the particles overcome the attraction forces keeping them together, therefore melting the solid and converting it to a liquid.

The melting point of a solid under normal atmospheric pressure is the particular temperature at which it becomes liquid. For example, ice melts at 273.16 K.

Fusion is the process by which a solid transforms into a liquid.

Latent Heat: The Concealed Energy

Latent heat is the thermal energy absorbed or released during a phase change of a substance without a temperature change. This energy is called hidden heat since it breaks intermolecular interactions instead of raising the temperature of the material.

Hidden Heat of Fusion

Latent heat of fusion is the quantity of heat energy required to turn 1 kilogramme of a solid into a liquid at its melting point at normal atmospheric pressure.

Its boiling point is the temperature at which a liquid begins to change into a gas under typical atmospheric circumstances.

Boiling is a bulk occurrence, which means that particles all across the whole volume of the liquid acquire sufficient energy to move into the gaseous form.

Water, for instance, boils at 100°C (or 373 K).

Vaporization's latent heat

Under atmospheric pressure, the latent heat of vaporisation is the quantity of heat energy needed to turn 1 kilogramme of a liquid into gas at its boiling point.

A gas cools and phases back into a liquid at a particular temperature. This procedure is called liquefaction or condensation.

Cloud formation—where water vapour rises from the Earth's surface, cools, and condenses into little water droplets—is a typical illustration of condensation.

Different Phase Changes

Sublimation is the direct transformation of a solid into a gaseous state without passing through the liquid phase (or vice versa).

The temperature at which a liquid freezes into a solid is called the freezing point.

A solid's temperature stays steady during melting as it takes in heat. The extra energy is used to overcome intermolecular interactions instead of raising the temperature, which explains this.

Likewise, the particles in steam have more energy in the shape of latent heat of vaporisation, therefore they are more active than water at the same temperature.

Pressure's Influence on Phase Changes

Applying high pressure and concurrently reducing the temperature allows gases to be turned into liquids. Gas particles move closer under compression; cooling lowers their energy, hence liquefying the gas.

When the pressure drops to 1 atmosphere, solid carbon dioxide (dry ice) sublimates straight into gas, skipping the liquid phase. This is why ice turns straight into carbon dioxide gas rather than melting.

Evaporation: Surface Slow Vaporisation

Evaporation is the process at temperatures below a liquid's boiling point whereby it changes into gas. Unlike boiling, which takes place all over the liquid, evaporation happens just at the surface.

Elements Affecting Evaporation

A higher surface area speeds up evaporation since more molecules are exposed to air.

Higher temperatures raise the kinetic energy of molecules, hence enabling them to more easily escape into the gaseous form.

What Pressure Does to Matter

By raising the pressure and lowering the temperature, gases can turn into liquids. Gas particles get squashed when high pressure is applied. If the temperature drops at the same time, the gas turns into a liquid.

When the pressure drops to 1 atmosphere, solid carbon dioxide (dry ice) goes straight from a solid state to a gaseous state, skipping the liquid phase. This is the reason why dry ice sublimates instead of melting.

Evaporation: Changing a liquid into a gas

Evaporation is the process by which a liquid below its boiling point turns into a gas.

Evaporation only happens on the liquid's top, while boiling happens all the way through the liquid.

Evaporation Factors Surface Area: More molecules can leave when the surface area is bigger, so the rate of evaporation is faster.

Temperature: Molecules have more energy when the temperature is higher, so they can evaporate more quickly.

Humidity: Less humidity means less water vapour is absorbed by the air, which speeds up drainage.

Speed of the Wind: Stronger winds quickly blow away particles that have evaporated, which leads to more evaporation.

Effects of Evaporation on Cooling

As liquid droplets evaporate, they take in heat energy from their surroundings and change into gases.

The temperature of the area around it drops because of this heat absorption, which has a cooling effect.

For instance, sweating cools the body because it takes heat from the skin and releases it into the air.

The Five Forms of Matter

Scientists have recently put matter into five different states, or phases:

Solids

Liquids

Gazes

A plasma

BEC stands for Bose-Einstein Condensate.

It is the fourth state of matter.
Plasma is made up of very charged particles that are super-excited and come in the form of ionised gases.

It's used in neon signs and fluorescent tubes, where an electric current powers the gas and makes it give off light.

Also, most of the matter in the world is plasma, which is what stars and lightning are made of.

What Is the Fifth State of Matter? The Bose-Einstein Condensate
Albert Einstein predicted a new state of matter called the Bose-Einstein Condensate (BEC) after Indian scientist Satyendra Nath Bose studied how particles behaved.

When a gas with a low density is cooled to very low temperatures close to absolute zero, BEC forms.

In this state, atoms stop being separate things and act like a single quantum object.

Important Ways to Measure Things

The kilogramme (kg) is the SI unit for mass.

The cubic meter (m³) is the SI unit for volume, but most people use litres (L) to measure volume:

A litre (L) is equal to a cubic decimetre (dm³).

1000 millilitres is equal to 1 litre (L).

One millilitre (mL) is equal to one cubic centimetre (cm³).

The SI measure for temperature is Kelvin (K). This is how Celsius and Kelvin relate to each other:

0°C is equal to 273.16 K, which is about the same as 273 K.

Add 273 to get from Celsius to Kelvin: T(K) = T(°C) + 273

Take away 273 to get from Kelvin to Celsius: T(K) - 273 = T(°C)

How to Find Gas Pressure

The atmosphere (atm) is a number used to measure how much pressure gases are putting on each other.

The Pascal (Pa) is the SI number for pressure.

101,325 Pascals is equal to 1 atmosphere.

Atmospheric pressure is the force that the air around us has on us.

It is used as a standard that the average atmospheric pressure at sea level is 1 atmosphere.

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