Learn: Particle Model of Matter

Welcome!Today we'll explore the Particle Model of Matter, a key concept in OCR GCSE Physics J249. This model helps us understand how particles behave in solids, liquids, and gases.

What is the Particle Model of Matter?The particle model explains the behaviour of matter based on the idea that all substances are made up of tiny particles. These particles are constantly moving and are arranged differently in solids, liquids, and gases.

States of MatterThere are three main states of matter: solid, liquid, and gas. Each state has different properties based on how its particles are arranged and move:Solid: Particles are tightly packed and vibrate in fixed positions.Liquid: Particles are close together but can move past each other.Gas: Particles are far apart and move randomly.

Changes of StateA change of state happens when a substance changes from one state of matter to another. Examples include melting (solid to liquid), freezing (liquid to solid), and evaporation (liquid to gas).These changes happen when energy is transferred to or from the particles, affecting their movement and arrangement.

DensityDensity is the mass of a substance per unit volume, calculated using the equation:Density = Mass / Volume. It's measured in kilograms per cubic metre (kg/m³) or grams per cubic centimetre (g/cm³).

Specific Heat CapacitySpecific heat capacity is the amount of energy needed to raise the temperature of 1 kg of a substance by 1°C. It is measured in joules per kilogram per degree Celsius (J/kg°C).The equation for energy transfer is: ΔE = mcΔθ, where:ΔE: Energy transferred (J)m: Mass (kg)c: Specific heat capacity (J/kg°C)Δθ: Temperature change (°C)

Internal EnergyInternal energy is the total energy stored in a substance, made up of the kinetic energy of moving particles and their potential energy due to their positions.Heating a substance increases its internal energy, which can lead to a change in temperature or state.

Review Time!Great work! You've learned about the particle model of matter, changes of state, density, specific heat capacity, and internal energy. Let's test your understanding with a few questions.