Understanding Matter: Properties and Composition

Matter in Our Surroundings

• Everything in the universe is composed of matter, which scientists have identified and named.
• Matter is anything that possesses mass and occupies space.
• Physical properties classify matter as solid, liquid, or gas.
• Chemical properties classify matter as elements, compounds, or mixtures.

Physical Nature of Matter

• All matter consists of particles that are very small in size.

Characteristics of Matter's Particles

• Matter particles have spaces between them; this is evident when one type of matter mixes with another (e.g., tea, coffee, or lemonade).
• Matter particles are continuously in motion, possessing kinetic energy.
• Known as diffusion, particles of matter intermix on their own.
• Increasing temperature accelerates the rate of diffusion and raises the kinetic energy of particles.
• Matter particles attract each other; this attraction keeps the particles together.
• The strength of attraction differs among various types of matter.
• Solid matter has Particles with a high force of attraction, making solids difficult to break.
• Liquid matter has Particles with a relatively lower force of attraction than solids.
• Gaseous matter has Particles with the least force of attraction.

States of Matter

• Matter can exist in three states: solid, liquid, and gas.

The Solid State

• Solids have a definite shape, distinct boundaries, fixed volumes, and negligible compressibility.
• Solids maintain their shape unless subjected to an external force; they may break under excessive force but are generally rigid.
• Salt and Sugar crystals have a fixed shape whether kept in a jar or on a plate.
• Solids typically have higher density compared to liquids and gases.
• Sponges are considered solids despite changing shape when compressed due to their porous nature and air cavities.

The Liquid State

• Liquids lack a fixed shape and distinct boundaries but have a fixed volume.
• Liquids assume the shape of their container and can flow, qualifying them as fluids.
• Aquatic animals can breathe underwater due to the diffusion of gases from the atmosphere into the water
• The increased particle movement and greater inter particle space of liquids leads to a higher diffusion rate than solids.

The Gaseous State

• Gases lack a fixed shape, distinct boundaries, and a fixed volume; they are highly compressible, unlike solids and liquids.
• Gases completely fill their container. An example is air expanding to fill its space.
• High compressibility allows gases to be compressed into small cylinders for easy transport; examples include LPG and CNG.
• Due to rapid diffusion gases quickly spread because of high-speed particles and large spaces between them, such as smelling food cooking.

Properties Comparison: Solid, Liquid, Gas

• Constituent Particles: Closely packed in solids, less closely packed in liquids, and very far apart in gases.
• Force of Attraction: Very strong in solids, less strong in liquids, and negligible in gases.
• Kinetic Energy: More in liquids, and Maximum in Gases.
• Shape and Volume: Definite shape and volume in solids, no definite shape or definite volume in liquids, and neither definite shape nor volume in gases.
• Density: High density in solids, lower than solid in liquids, and least density in gases.
• Diffusion: No diffusion in solids, yes diffusion in liquids, and easily diffused in Gases.

Changes of States of Matter

• Matter can change from one state to another and back.
• The interconversion of states happens due to changes in temperature and pressure.

Key Terms Related to Changes of State:

• Melting is the process of a solid turning into a liquid.
• The melting point is the temperature at which a solid turns into a liquid; for ice, it is 0°C.
• Freezing is the process of a liquid turning into a solid.
• The freezing point is the temperature at which a liquid turns into a solid; for water, it is 0°C.
• Evaporation is the process of a liquid turning into a gas, occurring at all temperatures.
• Boiling involves changing a liquid into a gas at a specific temperature, known as the boiling point.
• Water boils at 100°C.
• Condensation is the process of a gas turning into a liquid, which occurs when a gas loses heat energy.
• Sublimation is the process of a solid directly changing into a gas without becoming a liquid.

Effect of Change in Temperature:

• Increasing temperature raises the kinetic energy of particles.
• Increased kinetic energy causes particles to vibrate faster, overcoming attractive forces.
• Particles leave fixed positions and move more freely, converting Solids into liquids as space increases, reaching the melting point.
• Further Temperature Increase, weakens attraction and the liquid boils, converting it into a gas at its unique boiling point.
• Decreasing temperature (cooling) converts a gas into a liquid and a liquid into a solid.

Latent Heat

• During melting, temperature remains constant as heat energy is used to change the state by overcoming attraction forces between particles.
• Latent heat refers to the energy absorbed by a substance without a change in temperature. Latent means hidden.
• Water particles at 0°C have more latent heat than ice particles at the same temperature.
• Steam at 373 K contains more energy than water at the same temperature because of extra energy absorbed as latent heat of vaporization.
• Latent heat of fusion is the heat energy required to convert 1 kg of solid into liquid at its melting point at atmospheric pressure.
• Latent heat of vaporization is the heat energy required to convert 1 kg of liquid into a gas at its boiling point without a temperature rise.

Effect of Change in Pressure:

• Changing the pressure is also a process to change the state of a substance.
• Applying pressure and compressing a gas forces particles closer, increasing attraction, which can liquefy gases.

Evaporation

• Evaporation is the process where a liquid turns into a gas below its boiling point; an example is water evaporating from a wet cloth in sunlight.
• Liquids have particles with difference in kinetic energies.
• Surface particles that possess higher kinetic energies break away from attraction converted into vapor.

Factors Affecting Evaporation

• Temperature: Higher temperatures increase evaporation, because it provides more energy to liquid particles for vaporization.
• Surface Area: Larger surface areas speeds up evaporation, because there are more liquid molecules exposed to surroundings.
• Humidity: Higher humidity slows down evaporation, because its already saturated with moisture.
• Wind Speed: Increased air movement speeds up evaporation because movement carries away vapor.

Cooling Effect Due to Evaporation:

• Putting perfume, acetone, or petrol on the palm creates a cooling effect because they evaporate rapidly.
• Evaporation causes the liquid absorbs energy from the palm compensating for energy loss making it feel cool.
• This process is known as the cooling effect of evaporation.

Real-Life Examples of the Cooling Effect:

• People sprinkle water on hot surfaces to cool them, using the large latent heat of vaporization.
• Cotton clothes are worn in summer because they help to absorb sweat, which then evaporates and cools the body due to cotton's good absorption of water.
• Water droplets are a result of of contact between the water vapor in air with cold substances because it loses energy and converts to liquid.