# 2.2 The properties of matter

 Page 1 / 3

## The properties of matter

Let us now look at what we have learned about chemical bonds, intermolecular forces and the kinetic theory of matter, and see whetherthis can help us to understand some of the macroscopic properties of materials.

1. Melting point
Melting point
The temperature at which a solid changes its phase or state to become a liquid . The process is called melting and the reverse process (change in phase from liquidto solid) is called freezing .
In order for a solid to melt, the energy of the particles must increase enough to overcome the bonds that are holding the particlestogether. It makes sense then that a solid which is held together by strong bonds will have a higher melting point than one where the bonds are weak, because more energy (heat) is needed to breakthe bonds. In the examples we have looked at metals, ionic solids and some atomic lattices (e.g. diamond) have high melting points, whereas the meltingpoints for molecular solids and other atomic lattices (e.g. graphite) are much lower. Generally, the intermolecular forces between molecular solids are weaker than those between ionic and metallic solids.
2. Boiling point
Boiling point
The temperature at which a liquid changes its phase to become a gas . The process is called evaporation and the reverse process is called condensation
When the temperature of a liquid increases, the average kinetic energy of the particles also increases and they are able to overcomethe bonding forces that are holding them in the liquid. When boiling point is reached, evaporation takes place and some particles in the liquid become a gas. In other words, the energy of theparticles is too great for them to be held in a liquid anymore. The stronger the bonds within a liquid, the higher the boiling point needs to be in order tobreak these bonds. Metallic and ionic compounds have high boiling points while the boiling point for molecular liquids is lower.The data in [link] below may help you to understand some of the concepts we have explained. Not all of the substances in the table aresolids at room temperature, so for now, let's just focus on the boiling points for each of these substances. What do you notice?
 Substance Melting point ( ${}^{0}C$ ) Boiling point ( ${}^{0}C$ ) Ethanol (C 2 H 6 O) - 114,3 78,4 Water 0 100 Mercury -38,83 356,73 Sodium chloride 801 1465
You will have seen that substances such as ethanol, with relatively weak intermolecular forces, have the lowest boiling point, while substances withstronger intermolecular forces such as sodium chloride and mercury, must be heated much more if the particles are to have enough energy to overcome theforces that are holding them together in the liquid.

## Forces and boiling point

The table below gives the molecular formula and the boiling point for a number of organic compounds called alkanes (more on these compounds in grade 12). Refer to the table and then answer the questions that follow.

 Organic compound Molecular formula Boiling point ( ${}^{0}$ C) Methane CH 4 -161.6 Ethane C 2 H 6 - 88.6 Propane C 3 H 8 -45 Butane C 4 H 10 -0.5 Pentane C 5 H 12 36.1 Hexane C 6 H 14 69 Heptane C 7 H 16 98.42 Octane C 8 H 18 125.52

#### Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
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
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
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.
Bharti
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
Daniel
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
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
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
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
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
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
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.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
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
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

### Read also:

#### Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Siyavula textbooks: grade 10 physical science. OpenStax CNX. Aug 29, 2011 Download for free at http://cnx.org/content/col11245/1.3
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Siyavula textbooks: grade 10 physical science' conversation and receive update notifications?

 By Prateek Ashtikar By By By Mariah Hauptman