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Intramolecular and intermolecular forces

When atoms join to form molecules, they are held together by chemical bonds . The type of bond, and the strength of the bond, depends on the atoms that are involved. Thesebonds are called intramolecular forces because they are bonding forces inside a molecule ('intra' means 'within' or 'inside'). Sometimes we simply call theseintramolecular forces chemical bonds.

Intramolecular force

The force between the atoms of a molecule, which holds them together.

Examples of the types of chemical bonds that can exist between atoms inside a molecule are shown below. These will be looked at in moredetail in Grade 11.

  • Covalent bond Covalent bonds exist between non-metal atoms e.g. There are covalent bonds between the carbon and oxygen atoms in a molecule of carbon dioxide.
  • Ionic bond Ionic bonds occur between non-metal and metal atoms e.g. There are ionic bonds between the sodium and chlorine atoms in a molecule of sodium chloride.
  • Metallic bond Metallic bonds join metal atoms e.g. There are metallic bonds between copper atoms in a piece of copper metal.

Intermolecular forces are those bonds that hold molecules together. A glass of water for example, contains many molecules of water. These molecules are held together byintermolecular forces. The strength of the intermolecular forces is important because they affect properties such as melting point and boiling point . For example, the stronger the intermolecular forces, the higher the melting pointand boiling point for that substance. The strength of the intermolecular forces increases as the size of the molecule increases.

Intermolecular force

A force between molecules, which holds them together.

The following diagram may help you to understand the difference between intramolecular forces and intermolecular forces.

Two representations showing the intermolecular and intramolecular forces in water: space-filling model and structural formula.

It should be clearer now that there are two types of forces that hold matter together. In the case of water, there are intramolecularforces that hold the two hydrogen atoms to the oxygen atom in each molecule of water (these are the solid lines in the above diagram). There are also intermolecular forces between each of these water molecules . These intermolecular forces join the hydrogen atom from one molecule to the oxygenatom of another molecule (these are the dashed lines in the above figure). As mentioned earlier, these forces are veryimportant because they affect many of the properties of matter such as boiling point, melting point and a number of other properties. Before we go on to look at some of these examples, it is importantthat we first take a look at the Kinetic Theory of Matter .

Intramolecular and intermolecular forces

  1. Using ammonia gas as an example...
    1. Explain what is meant by an intramolecular force or chemical bond .
    2. Explain what is meant by an intermolecular force.
  2. Draw a diagram showing three molecules of carbon dioxide. On the diagram, show where the intramolecular and intermolecular forcesare.
  3. Why is it important to understand the types of forces that exist between atoms and between molecules? Try to use some practical examples in your answer.

Questions & Answers

what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
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
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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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