Olevels Chemistry Notes
Kinetic Particle theory
kinetic particle theory deals with states of matter and attempts to define to describe the states of matter the differences in their properties (Solid, Liquid and Gases) and explain the changes of their state from one form to another. Now that, what kinetic particle theory is used for, what this theory itself is...Kinetic particle theory states that all particles are made of tiny particles and they are in constant random motion..using this deduction of theory properties of states of matter and changes in their state are defined. There are basically 3 states of matter namely:
1) Solid
2) Liquid &
3) Gas.
Now using this theory states of matters can be defined very easily. How so ??
well, we all know that solids have fixed shape and their shape isn't something that can be changed on desire or demand..it is because the particle sin solid are held firmly together in theory place by strong forces of attraction that wont allow these particles to move freely ad in gases and some how in liquids they only have enough liberty to vibrate in their position this is why they have fixed shape and volume-fixed volume because they cannot be pressed as their particles are already very close together
using same theory liquids and gases can be explained but before you go in to reading this further try to explain yourself a little and then check out the post further to look how much of it you got right...
now, particles in liquid according to theory are arranged in disorderly manner and have relatively more kinetic energy than particles in solid since they are not arranged in order so they can slide over each other which is why they do not have fixed shape.but they do have fixed volume because the particles in liquid are also held closer together therefore it cannot be compressed.
as for gasses they neither have fixed volume nor shape their particles have the highest energy of all states and are farther apart from each other.
now, since we know their basic internal structure of what actually is happening inside all states of matter it is now all more easier to explain changes in matter.
consider an ice cube and heat it after some time the energy from heat will exciter solid particles and starts to move vigorously and when when the energy from heat is sufficient is enough to overcome forces of attraction that were holding solid's particles they will break away from their firm position and starts to slide over each other the solid have changed to liquid if you keep heating this liquid it will gain even more energy to break away from forces of attraction still present liquid to become gas.
similarly, the reverse will happen when liquid is left to freeze, molecules will loose energy and began to silt firmly in their place. one thing important to remember is that during change of state either from solid to liquid, liquid to gas or from gas to liquid and liquid to solid te temperature remains constant which indicated on graphs as straight horizontal lines.( it is important to remember as many mcqs comes from this concept)
Evaporation: it is a process by which some of the surface particles gain enough energy to escape as gas which leaves behind the cooling effect. for example cooling effect after sweating, or clothes left to dry. it is a slow process that occurs just below the boiling point and it occurs only at the surface while boiling takes place throughout.
Sublimation: change of a solid state directly to gas without going through liquid state. it occurs because some paricles have enough energy to break away as gas with being going through liquid like iodine and ammonium chloride. substance that sublime may also do reverse which is condensation.
Condensation: when gases are cooled sufficiently they changes in to liquid.
this is to remember that when substances are haeated they gain energy and changes in to a substance that has more liberty for energy rich particles while when they are cooled off they lose energy and reverse happens
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