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Natural sciences

Grade 8

Matter: classification

Module 16

Crystals and solutions

  • In the previous unit, mention was made of the formation of snowflakes.

Snow Crystals

  • Each snowflake is unique and is formed when drops of water vapour in the atmosphere condense as snow crystals.
  • Snow crystals develop six “arms” from a six-sided prism. Each “arm” grows differently as it is affected by continual minute temperature variations
  • Snow crystals combine to form snowflakes.
  • Some of the most valuable stones in the world consist of solid matter in the form of crystals.
  • Diamonds, rubies and sapphires are examples of precious stones. The atoms of these crystals form specific patterns.
  • Crystals have flat sides known as facets – they can take the form of triangles, rectangles, or many other shapes.
  • Minerals can be identified according to the crystalline form.
  • The basic form of crystals vary – salt, for instance, is cubical.
  • Most crystals have to be polished to reveal their beauty.

 Do you know the following? 

Sand is composed of quartz crystals. These crystals are shaped by constantly being knocked or rubbed against each other.

Read about QUARTZ WATCHES

Google.com (quartz +sand)

Rochhounding ar.com

Class Activity: Making a Solution

  • Fill a glass beaker with cold water.
  • Add a teaspoon of salt or sugar to the water and stir.
  • Continue stirring until the substance stops dissolving.

1. How many spoonfuls of the substance did you add?

  • Repeat the experiment with an equal amount of hot water.

2. What do you observe?

3. What deduction can be made?

4. Explain why warm water is more effective as a solvent:

  • Pour the solutes into watch-glasses and leave these on the classroom window sill for some days.

5. What do you observe after a few days?

6. What happened to the water?

  • Examine the crystals through a magnifying glass or a microscope.

Assignment: draw a couple of crystals to show their form.

Assessment for demonstration

Are you able to make correct deductions and communicate your findings?

[LO 1.3; LO 2.3]

Class project

Assignment:

Compile a scientific report on your investigation.

Grow your own crystals at home or in the classroom

You will need:

  • alum powder (obtainable from a chemist)
  • glass jars
  • cotton thread and a pair of scissors
  • a drinking straw
  • elastic band
  • Fill the jar with hot water.
  • Add alum powder by the method explained in the previous experiment – you will obtain a saturated solution. Use a watch-glass for crystals to form.
  • Use the cotton thread to attach the crystals to the drinking straw and suspend them in the jar to a depth of three-quarters down the jar.
  • Bend the straw and firmly attach it to the jar with the elastic band to hold it in position.

You will see crystals developing within a few days.

N.B.: Your educator could also let you grow copper sulphate crystals in the classroom.

Assessment of class project

Were you able to plan and execute the project, evaluate the data and apply your knowledge by handing in a properly compiled scientific report?

[LO 1.1; LO 1.2; LO 1.3; LO 2.4]

Problem Solving

Suppose you have a saturated solution, with excess crystals lying at the bottom of the beaker: Why would the crystals disappear if you began to heat the saturated solution slowly?

Assessment of problem solving

Were you able to provide an acceptable explanation for the problem?

[LO 2.4]

 Do you know the following? 

The gigantic rocks that form the Giant’s Causeway in Northern Ireland are hexagonal crystals that were formed when molten rock cooled down rapidly.

www.geocities.com/amegman_uk/symmetry.html

Assessment

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

Learning outcome 2: Constructing science knowledge

The learner will know and be able to interpret and apply scientific, technological and environmental knowledge.

ASSESSMENT STANDARD: We know this when the learner

2.3 is able to interpret information.

2.4 is able to apply knowledge.

Memorandum

CLASS ACTIVITY: MAKING SOLUTIONS

  • Warm water contains more energy and crystals dissolve much faster in this
  • Evaporation leads to crystallisation

ASSIGNMENT: CLASS PROJECT

  • The scientific report must include the following:

Purpose

Method

Materials

Results

Deduction

PROBLEM SOLVING:

  • The particles of warm water have more kinetic energy and are therefore further apart – more salt particles can fit into the spaces.

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
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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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