Kinetic Particle theory

Doc Brown's Chemistry KS4 science GCSE/IGCSE Revision Notes States of Matter gas-liquid-solid revision notes Part 1 The particle model and properties of the gases, liquids and solids, state changes and solutions

 1.1a. The particle model of a Gas

• WHAT IS THE GASEOUS STATE OF MATTER?
• WHAT ARE THE PROPERTIES OF A GAS?
• HOW DO GASEOUS PARTICLES BEHAVE?
• A gas has no fixed shape or volume, but always spreads out to fill any container.
• There are almost no forces of attraction between the particles so they are completely free of each other.
• The particles are widely spaced and scattered at random throughout the container so there is no order in the system.
• The particles move rapidly in all directions, frequently colliding with each other and the side of the container.
• With increase in temperature, the particles move faster as they gain kinetic energy.

Diffusion is faster in gases than liquids where there is more space for them to move (experiment illustrated below) and diffusion is negligible in solids due to the close packing of the particles

• •  1.1b. The particle model of a Liquid
    • WHAT IS THE LIQUID STATE OF MATTER?
    • WHAT ARE THE PROPERTIES OF A LIQUID?
    • HOW DO LIQUID PARTICLES BEHAVE?
    • A liquid has a fixed volume at a given temperature but its shape is that of the container which holds the liquid.
    • There are much greater forces of attraction between the particles in a liquid compared to gases, but not quite as much as in solids.
    • Particles quite close together but still arranged at random throughout the container, there is a little close range order as you can get clumps of particles clinging together temporarily.
    • Particles moving rapidly in all directions but more frequently collisions with each other than in gases due to shorter distances between particles.
    • With increase in temperature, the particles move faster as they gain kinetic energy, so increased collision rates, increased collision energy and increased rate of diffusion.
    •  1.1c. The particle model of a Solid
      • WHAT IS THE SOLID STATE OF MATTER?
      • WHAT ARE THE PROPERTIES OF A SOLID?
      • HOW DO SOLID PARTICLES BEHAVE?
      • A solid has a fixed volume and shape at a particular temperature unless physically subjected to some force.
      • The greatest forces of attraction are between the particles in a solid and they pack together as tightly as possible in a neat and ordered arrangement.
      • The particles are too strongly held together to allow movement from place to place but the particles vibrate about their position in the structure.
      • With increase in temperature, the particles vibrate faster and more strongly as they gain kinetic energy.
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• Diffusion and brownian motion
• • • Diffusion is responsible for the spread of odours even without any air disturbance e.g. use of perfume, opening a jar of coffee or the smell of petrol around a garage.
    • The rate of diffusion increases with increase in temperature as the particles gain kinetic energy and move faster.
    • Other evidence for random particle movement including diffusion:
      • When smoke particles are viewed under a microscope they appear to 'dance around' when illuminated with a light beam at 90^o to the viewing direction. This is because the smoke particles show up by reflected light and 'dance' due to the millions of random hits from the fast moving air molecules. This is called 'Brownian motion' (see below in liquids). At any given instant of time, the hits will not be even, so the smoke particle get a greater bashing in a random direction.
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    Using Kinetic Particle Theory to explain some of the matters' properties
    
    
    Example:In the property of gas being compressible is due to the empty spaces in between the gas molecules and can be compressed to a denser state.
    Example:In liquid having no definite shape is due to the liquid molecules sliding and flowing past one another and is able follow the shape of any container that is equal or more than the volume.
    Example:In solid having both a definite shape and volume is due to the solid molecules having a rigid structure and have strong attractive forces called intermolecular forces.
    As we can see,the kinetic particle theory allows us to confirm the properties of the matters and allows more space to explored in diffusion and brownian motion which lead to discovery of osmosis and so on,all of the concepts having a hot-cold relationship with each other.This is the importance of KPT.
    
    
    Reflection-
    I feel that to discover and come up with the KPT requires a lot of observation and reading from other scientists' founding.From what i found out,the coming up of the KPT is through the hard work and records of many scientists,starting from 
    1738 when Daniel Bernoulli published Hydrodynamica and gained a turning point when 
     Albert Einstein's (1905) and Marian Smoluchowski's (1906)^[12] papers on Brownian motion, which succeeded in making certain accurate quantitative predictions based on the kinetic theory.All these requires an extensive understanding and healthy skepticism to challenge and develop to a big founding.In the KPT,we can see the relay of many scientists' sweat going on even if the gap was 200 years,so my message is that we should persevere in whatever we are doing as a feat wouldn't be achievable if we even lack the guts to do what others despise.
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