Short Notes - Matter In Our Surroundings, Matter - Its Nature and Behavior, Science, Class 9 PDF Download

Facts that Matter

Introduction

• Everything in this universe is made of materials which scientist has named ‘matter’.

• Matter is made up of very small tiny particles.

• Matter is anything that occupies space and has mass.

• Particles of matter have space between them and are continuously moving.

• Particles of matter attract each other.

• States of Matter: It has three states.

• Matter can change its state from solid to liquid and from liquid to gas and vice-versa

•  Effect of temperature: On increasing the temperature, the particles gain energy and start vibrating with greater energy. Due to increased kinetic energy the particles overcome the force of attraction and a new state is obtained.

• Melting point: The minimum temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point.

• Boiling point: The temperature at which a liquid starts boiling at the atmospheric pressure is known as its boiling point. Boiling is a bulk phenomena.

• Latent heat of fusion: The amount of heat energy required to change 1 kg of a solid into liquid at its melting point is called the latent heat of fusion of the solid. 

• Latent heat of vapourization: The amount of heat energy required to change 1 kg of a liquid to vapour at atmospheric pressure, at its boiling point is called the latent heat of vapourization of the liquid.

• Sublimation: A change of state directly from solid to gas without changing to liquid state is called sublimation.

• Effect of change of pressure on matter: On applying pressure, the particles of matter can be brought close together and the state of matter can be changed. For example, CO₂ gas can be solidified by applying pressure and lowering temperature.

• Evaporation: The phenomenon of changing of a liquid into its vapour state at any temperature below its boiling point is called evaporation. Evaporation is a surface phenomena.

• Factors affecting evaporation.
  – An increase in surface area increases evaporation.
  – An increase in temperature increases the rate of evaporation.
  – A decrease in humidity increases the rate of evaporation.
  – An increase in wind speed increases the rate of evaporation.

• Evaporation causes cooling effect

Some measurable quantities and their units​