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The kinetic theory of matter

The kinetic theory of matter helps us to explain why matter exists in different phases (i.e. solid, liquid and gas), and how matter can change from one phase to the next. The kinetic theory of matter also helpsus to understand other properties of matter. It is important to realise that what we will go on to describe is only a theory . It cannot be proved beyond doubt, but the fact that it helps us to explain our observations of changes in phase, and otherproperties of matter, suggests that it probably is more than just a theory.

Broadly, the Kinetic Theory of Matter says that:

  • Matter is made up of particles that are constantly moving.
  • All particles have energy , but the energy varies depending on whether the substance is a solid, liquid or gas. Solid particles have the least amount ofenergy and gas particles have the greatest amount of energy.
  • The temperature of a substance is a measure of the average kinetic energy of the particles.
  • A change in phase may occur when the energy of the particles is changed.
  • There are spaces between the particles of matter.
  • There are attractive forces between particles and these become stronger as the particles move closer together. These attractive forces will either be intramolecularforces (if the particles are atoms) or intermolecular forces (if the particles are molecules). When the particles are extremely close, repulsive forces startto act.

[link] summarises the characteristics of the particles that are in each phase of matter.

Table summarising the general features of solids, liquids and gases.
Property of matter Solid Liquid Gas
Particles Atoms or molecules Atoms or molecules Atoms or molecules
Energy and movement of particles Low energy - particles vibrate around a fixed point Particles have less energy than in the gas phase Particles have high energy and are constantly moving
Spaces between particles Very little space between particles. Particles are tightly packed together Smaller spaces than in gases, but larger spaces than in solids Large spaces because of high energy
Attractive forces between particles Very strong forces. Solids have a fixed volume. Stronger forces than in gas. Liquids can be poured. Weak forces because of the large distance between particles
Changes in phase Solids become liquids if their temperature is increased. In some cases a solid may become a gas if the temperature is increased. A liquid becomes a gas if its temperature is increased. It becomes a solid if its temperature decreases. In general a gas becomes a liquid when it is cooled. (In a few cases a gas becomes a solid when cooled). Particles have less energy andtherefore move closer together so that the attractive forces become stronger, and the gas becomes a liquid (or a solid.)

The following presentation is a brief summary of the above. Try to fill in the blank spaces before clicking onto the next slide.

Let's look at an example that involves the three phases of water: ice (solid), water (liquid) and water vapour(gas). Note that in the [link] below the molecules in the solid phase are represented by single spheres, but they wouldin reality look like the molecules in the liquid and gas phase. Sometimes we represent molecules as single spheres in the solid phase to emphasise the smallamount of space between them and to make the drawing simpler.

The three phases of matter

Taking water as an example we find that in the solid phase the water molecules have very little energy and can't move away from eachother. The molecules are held closely together in a regular pattern called a lattice . If the ice is heated, the energy of the molecules increases. This means that some of the water molecules are ableto overcome the intermolecular forces that are holding them together, and the molecules move further apart to form liquid water . This is why liquid water is able to flow, because the molecules are more free to move than they were in the solid lattice. If themolecules are heated further, the liquid water will become water vapour, which is a gas. Gas particles have lots of energy and are far away from each other.That is why it is difficult to keep a gas in a specific area! The attractive forces between the particles are very weak and they are only loosely heldtogether. [link] shows the changes in phase that may occur in matter, and the names that describe these processes.

Changes in phase

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Siyavula textbooks: grade 10 physical science. OpenStax CNX. Aug 29, 2011 Download for free at http://cnx.org/content/col11245/1.3
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