# 2.2 The kinetic molecular theory  (Page 2/2)

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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.

## Summary

• There are three states of matter: solid, liquid and gas.
• Diffusion is the movement of particles from a high concentration to a low concentration. Brownian motion is the diffusion of many particles.
• The kinetic theory of matter attempts to explain the behaviour of matter in different phases.
• The kinetic theory of matter says that all matter is composed of particles which have a certain amount of energy which allows them to move at different speeds depending on the temperature (energy). There are spaces between the particles and also attractive forces between particles when they come close together.
• Intramolecular force is the force between the atoms of a molecule, which holds them together. Intermolecular force is a force between molecules, which holds them together.
• Understanding chemical bonds, intermolecular forces and the kinetic theory of matter can help to explain many of the macroscopic properties of matter.
• Melting point is the temperature at which a solid changes its phase to become a liquid . The reverse process (change in phase from liquid to solid) is called freezing . The stronger the chemical bonds and intermolecular forces in a substance, the higher the melting point will be.
• Boiling point is the temperature at which a liquid changes phase to become a gas. The reverseprocess (change in phase from gas to liquid) is called condensing . The stronger the chemical bonds and intermolecular forces in a substance, the higher the boilingpoint will be.
• Density is a measure of the mass of a substance per unit volume.
• Viscosity is a measure of how resistant a liquid is to flowing.

## End of chapter exercises

1. Give one word or term for each of the following descriptions.
1. The property that determines how easily a liquid flows.
2. The change in phase from liquid to gas.
2. If one substance A has a melting point that is lower than the melting point of substance B, this suggests that...
1. A will be a liquid at room temperature.
2. The chemical bonds in substance A are weaker than those in substance B.
3. The chemical bonds in substance A are stronger than those in substance B.
4. B will be a gas at room temperature.
3. Boiling point is an important concept to understand.
1. Define 'boiling point'.
2. What change in phase takes place when a liquid reaches its boiling point?
3. What is the boiling point of water?
4. Use the kinetic theory of matter and your knowledge of intermolecular forces to explain why water changes phase at this temperature.
4. Describe a solid in terms of the kinetic molecular theory.
5. Refer to the table below which gives the melting and boiling points of a number of elements and then answer the questions thatfollow. ( Data from http://www.chemicalelements.com )
 Element Melting point Boiling point ( ${}^{°}\mathrm{C}$ ) copper 1083 2567 magnesium 650 1107 oxygen -218,4 -183 carbon 3500 4827 helium -272 -268,6 sulphur 112,8 444,6
1. What state of matter (i.e. solid, liquid or gas) will each ofthese elements be in at room temperature?
2. Which of these elements has the strongest forces between its atoms? Give a reason for your answer.
3. Which of these elements has the weakest forces between its atoms? Give a reason for your answer.

how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Do somebody tell me a best nano engineering book for beginners?
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
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.
Tarell
what is the actual application of fullerenes nowadays?
Damian
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.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
so some one know about replacing silicon atom with phosphorous in semiconductors device?
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.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
what is nano technology
what is system testing?
preparation of nanomaterial
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
what is system testing
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
how did you get the value of 2000N.What calculations are needed to arrive at it
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The fundamental frequency of a sonometer wire streached by a load of relative density 's'are n¹ and n² when the load is in air and completly immersed in water respectively then the lation n²/na is
Properties of longitudinal waves