Matter in Our Surroundings

Key points

• 1. Matter is anything that has mass and occupies space.
• 1. Matter is made up of extremely small particles.
• 1. Particles of matter have spaces between them.
• 1. Particles of matter are continuously moving.
• 1. Particles of matter attract each other.
• 1. The three main states of matter are solid, liquid and gas.
• 1. Solids have a definite shape, fixed volume and rigid structure.
• 1. Liquids have a definite volume but no definite shape.
• 1. Gases have neither a definite shape nor a definite volume.
• 1. The force of attraction is strongest in solids and weakest in gases.
• 1. The kinetic energy of particles is highest in gases and lowest in solids at the same temperature.
• 1. Diffusion is the intermixing of particles of two or more substances.
• 1. Temperature increases the kinetic energy of particles.
• 1. Melting is the conversion of a solid into a liquid.
• 1. The melting point is the temperature at which a solid changes into a liquid.
• 1. The melting point of ice is 0°C or 273.15 K.
• 1. Boiling is the rapid conversion of a liquid into vapour.
• 1. The boiling point of water is 100°C or 373.15 K at atmospheric pressure.
• 1. Latent heat is the heat energy absorbed or released during a change of state without a change in temperature.
• 1. Latent heat of fusion is the heat required to convert a solid into a liquid at its melting point.
• 1. Latent heat of vaporisation is the heat required to convert a liquid into gas at its boiling point.
• 1. Sublimation is the direct conversion of a solid into gas without passing through the liquid state.
• 1. Evaporation is a surface phenomenon that occurs at temperatures below the boiling point.
• 1. Evaporation causes cooling because high-energy particles escape from the surface.
• 1. The rate of evaporation increases with an increase in surface area.
• 1. The rate of evaporation increases with an increase in temperature.
• 1. The rate of evaporation decreases with an increase in humidity.
• 1. The rate of evaporation increases with an increase in wind speed.
• 1. Condensation is the conversion of gas into liquid by cooling.
• 1. Increasing pressure and decreasing temperature can convert gases into liquids.
• 1. Kelvin is the SI unit of temperature.
• 1. Temperature in Kelvin = Temperature in Celsius + 273.15.
• 1. Plasma is an ionised state of matter consisting of charged particles.
• 1. Bose-Einstein condensate is a special state of matter formed at extremely low temperatures.