The Particle Model of Matter The particle model describes the behavior and properties of matter based on the arrangement and movement of its constituent particl...
The particle model describes the behavior and properties of matter based on the arrangement and movement of its constituent particles (atoms or molecules). In GCSE Physics, this model helps us understand the three states of matter: solids, liquids, and gases.
Density is a measure of the mass per unit volume of a substance. It can be calculated as:
Density = Mass / Volume
The density of regular solids and liquids can be determined through measurements of mass and volume. For irregular solids, the displacement method using a Eureka can (required practical) measures the volume of the displaced liquid, allowing density calculation.
Problem: A rock with a mass of 120 g is dropped into a Eureka can filled with water. The water level rises by 50 cm³. Calculate the density of the rock.
Solution:
Internal energy is the total kinetic energy (from particle movements) and potential energy (from particle interactions) of a substance. Heating a substance increases its internal energy, either by increasing the temperature (raising the kinetic energy of particles) or causing a change of state (breaking intermolecular bonds).
The specific heat capacity is the amount of energy required to raise the temperature of 1 kg of a substance by 1°C. The specific latent heat is the energy required for a substance to change state (fusion for solid to liquid, vaporization for liquid to gas) per unit mass, given by the equation:
Energy Transfer = Mass × Specific Latent Heat
For a fixed mass of gas, the relationship between pressure, volume, and temperature can be explained by the particle model. Higher temperatures increase the kinetic energy and frequency of particle collisions, resulting in greater pressure on the container walls. Decreasing the volume increases particle concentration and collision rate, raising the pressure.