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Natural sciences

Grade 8

Matter: classification

Module 21

Compounds and mixtures

Prior Knowledge

  • In the previous section of the work we learnt what elements are and that they consist of atoms.
  • We mentioned that atoms do not occur in isolation, but are combined in molecules.

Class activity: practical investigation

Investigation of physical qualities of elements

Your educator will help you to investigate the physical features of individual elements and the changes that occur when they combine.

1. Describe the iron filings:

2. Describe the sulphur:

3. Is the iron attracted by the magnet?

4. Is the sulphur attracted by the magnet?

5. What do you deduce from this?

6. Add a little carbon bisulphide (CS 2 ) to the iron.

What happens?

7. Add a little carbon bisulphide (CS 2 ) to the sulphur.

What happens?

8. What do you deduce from this?

Pour the contents of the test tubes into two watch-glasses.

9. What do you see when the carbon bisulphide has evaporated?

Investigation of physical qualities of mixtures

Add iron filings to the sulphur:

1. What does the mixture look like?

2. What happens when the magnet is brought closer to the mixture?

3. What can you deduce from this?

4. Now add CS 2 to the mixture. What happens?

5. Can you separate the mixture?

6. Suggest two methods of separation

Class activity (continued): demonstration

1. what happens when iron and sulphur are heated together?

2. Is a new substance formed? Explain your answer?

3. Has the substance retained any magnetic qualities?

4. Is this substance soluble in carbon bisulphide?

5. Can the substance be reconverted to the original elements?

6. What was required for the reaction to occur?

7. What kind of transfer of energy took place?


Assessment of experiment

Were you able to plan the steps (AS 1.1), execute them (AS 1.2) and communicate your findings (AS 1.3)?

[LO 1.1; LO 1.2; LO 1.3]


Learning outcome 1: Scientific investigations

The learner will be able to act confidently on curiosity about natural phenomena, and to investigate relationships and solve problems in scientific, technological and environmental contexts.

ASSESSMENT STANDARD: We know this when the learner

1.1 is able to plan investigations;

1.2 is able to execute an investigation and collect data;

  • is able to evaluate data and communicate findings



1. grey, hard

2. yellow powder

3. yes

4. no

5. Metals are magnetic.

6. nothing

7. sulphur dissolves

8. Metals do not dissolve in carbon bisulphide.

9. crystals – sulphur


1. yellow-grey

2. Only iron filings are attracted.

3. Only metal is magnetic.

4. Only sulphur dissolves.

5. yes

6. Dissolves S and evaporates again – crystals back on magnet.


1. Fused into a new substance.

2. yes – looks different; own qualities

3. no

4. no

5. yes, with effort

6. heat

7. heat – chemicals

8. Complete the following comparative table.

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, Natural sciences grade 8. OpenStax CNX. Sep 12, 2009 Download for free at http://cnx.org/content/col11050/1.1
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