GRADE 8 SCIENCE
IONIC AND COVALENT COMPOUNDS LAB INVESTIGATION
Background
We know that atoms bond to each other. Scientists have found that there are only three types of
bonds: ionic bonds, covalent bonds, and metallic bonds. If atoms have an ionic bond, the solid
they make is called an ionic compound. If atoms have a covalent bond, the solid they make is
called a covalent compound.
B Research Question
What are the physical properties of ionic compounds and covalent compounds?
C Variables
Complete the following table with 3 constant variables for each experiment.
Experiment
1
Independent Variable
Dependent Variable
Smell
2
Melting point
3
Microscopic structure
4
Ionic and covalent
solid
Hardness
5
Solubility
6
Electrical conductivity
7
Flame test
Constant Variables
Same distance between person and
beakers, amount of substance in each
beaker and environment the beaker is in
eg classroom and toilet
Distance between burner and substance,
strength of the fire and if there is any
interference eg wind
The quality of the microscope, the state
of the lens and the distance between
substance and microscope
The tool that you use to test, the amount
of times that you use that took against
the substance and the quality of the tool
The kind of liquid that you use, the
amount of substance you put in the liquid
and the amount of liquid there is
The kind of battery, the kind of light and
the strength of the electricity
The strength of the flame, any
interference and the amount of substance
D Hypothesis
Complete these statements for the six properties you are testing. A good hypothesis will help you to
write a good conclusion.
If a solid has strong bonds between its atoms, then
 the smell will be weak because the particles will be held together closely and so they will not
float into the air to be sniffed.
 the melting point will be high because the stronger the bond the higher the temperature will
need to be in order to break the bonds.
 the microscopic structure will be strong because of the strong bonds the particles have with
each other.
 the hardness will be high because of the strong bonds the particles have.
 the solubility will be low because it will take more time for water to break down a strong bonded
solid then it would a weak bonded solid.
 the electrical conductivity will be strong because the particles are close together, so they
transfer more easily.
E Equipment and Materials
You will need all of this equipment at one point in the investigation. Collect only the equipment you
need for each new experiment.


Lab coat (to wear throughout the practical investigation)
Safety glasses (to wear when appropriate - you choose when and your teacher will check!)
 Sodium carbonate (ionic compound)
 1 microscope
 Naphthalene (covalent compound)
 4 test tubes
 Pen for labeling glass containers
 Water
 2 spatulas
 2 small glass beakers
 1 watch glass
 1 lamp
 2 test tubes and test tube holder
 1 ammeter
 2 test tube tongs
 1 battery or power supply pack
 Spirit burner or Bunsen burner
 3 electrical cables
 Stopwatch
 2 carbon electrodes
 2 microscope slides
 2 flame-test-sticks
F Method and G Diagram
Work carefully through each experiment. Record your observations carefully after every experiment.
Experiment 1: Smell
1. Use a spatula to place a sample of each solid on a watch glass.
2. Observe and record your observations.
Experiment 2: Melting Point
1. Put 2 spatulas of each solid in a test tube (use two separate test tubes).
2. Heat each test tube for the same amount of time until one of the solids melts.
3. Continue heating them for three more minutes.
4. Observe and record your observations.
Experiment 3: Microscopic Structure
1. Place a sample of each solid on a microscope slide.
2. View the solid under the microscope
3. Observe and record your observations.
Experiment 4: Hardness
1. Attempt to crush some of each solid on the watch glass using the spatula.
2. Observe and record your observations.
Experiment 5: Mixing with other Liquids
1. Put 2 cm of water (an ionic liquid) into 2 different test tubes.
2. Add a spatula-tip of each solid to separate test tubes (use one test tube for each solid).
3. Observe and record your observations.
4. Put 2 cm of 2-propanol (a covalent liquid) into 2 different test tubes.
5. Add a spatula-tip of each solid to separate test tubes (use one test tube for each solid).
6. Observe and record your observations.
Experiment 6: Electrical Conductivity
1. Construct an electrical conductivity tester similar to the diagram (use a power supply instead of
a battery and add an ammeter in series with the lamp)
2. Half-fill 2 beakers with water
3. Stir a spatula tip full of each solid into separate beakers (use one beaker for each solid).
4. Observe and record your observations.
Experiment 7: Flame Test (Just for Fun! – Not really to do with ionic and covalent solids)
1. Put a small amount of each solid on the flame-test-stick and hold each solid in a flame.
2. Observe and record your observations.
H Observations
Results of Ionic and Covalent Experiments
Experiment
No.1-Smell
Hypothesis
The substance that has
the stronger bond will
have a weaker smell.
The substance with the
stronger bond would be
more heat resistant
than the one with weak
bonds.
Substance A
Substance A had a
much stronger smell
than Substance B.
Substance A was but
over the Bunsen Burner
(blue flame) and it
melted in 8 seconds.
The substance that has
a strong bond will be
more closely packed.
The substance that has
the strongest particle
bonds will be stronger.
Substance A had a
diamond-like structure
with specks in them.
Substance A was easy
to crush.
No.5-Solubility
(We tested with both
alcohol and water)
The substance with the
stronger bond will be
less soluble.
Substance A was not
soluble.
No.6-Electric
conductivity
The substance with the
stronger bond will be a
better conductor than
the one with weak
bonds.
N/A
Substance A was not
able to conduct
electricity.
No.2-Heat resistance
No.3-Microscopic
structures
No.4-Hardness
No.7-Flame test
Substance A made
black smoke with
particles when it was
put on a rod and held
above a Bunsen Burner
(blue flame).
Substance B
Substance B had little
to no smell.
Substance B was put
over the Bunsen Burner
(blue flame) for 3:00
but the most that it did
was change the parts
on the bottom to
brown.
Substance B were small
specks.
Substance B was hard
to crush because the
contents were already
very small.
Substance B was
slightly soluble, but
could be separated
through decanting.
Substance B was able
to slightly conduct
electricity.
Substance B just
melted when it was
placed on a rod and
held above the Bunsen
Burner (blue flame).
I Presenting and Processing Data (Not required in this investigation)
J Conclusion
Insert your conclusion here.
1. Answer the research question.
The properties of ionic and covalent compounds are that ionic compounds look like crystals, have
high melting points and are slightly soluble in water. Covalent compounds have low melting points
and are poor conductors of electricity, and they are not soluble.
2. State whether your results support your hypothesis.
Yes I think that the majority of our results support the hypothesis that were made.
3. Do some research about the strength of ionic and covalent bonds and explain why the ionic
compound showed the properties it showed, and why the covalent compound showed the
properties it showed.
Sometimes ionic compounds are sometimes stronger and sometimes weaker than covalent
compounds, even though ionic bonds are easier to break than covalent bonds. I think that
Substance A was a covalent compound and Substance B was an ionic compound.
K Evaluation (Not required in this investigation)
L Real Life Application
Add two real life applications of ionic compounds and two real life applications of covalent compounds
here. You may not use the examples given in your textbook – find something else!
Two real life applications for ionic compounds are for the construction of glass and for the making of
salt, which we use to season our meals. Two real life applications for covalent compounds are one of
the most obvious, water. Without water we would probably die because we are missing more than half
of our body and because we need it to drink. Another one is perfumes and deodorants which many
people use.
M Works Cited
Add Works Cited (and in-text citations) if necessary.
"Explain Ionic Compounds in Use for Everyday Life and How They Influence Global Warming." College &
High School Chemistry Help. N.p., n.d. Web. 13 Feb. 2013.
http://www.mychemistrytutor.com/questions/explain-ionic-compounds-use-everyday-life-and-how-theyinfluence-global-warming
"What Is the Difference Between an Ionic and Covalent Chemical Bond?" About.com Chemistry. N.p., n.d.
Web. 13 Feb. 2013.
http://chemistry.about.com/od/chemistrystudentfaqs/f/bondtypes.htm
Criterion B: Communication in Science
Student’s Teacher’s
Opinion Decision
SWA MYP Descriptor

0


1–2



3–4



5–6

The student does not reach a
standard described by any of the
descriptors given below.
The student uses a limited range of
scientific language correctly.
The student communicates scientific
information with limited
effectiveness
When appropriate to the task, the
student makes little attempt to
document sources of information.
The student uses some scientific
language correctly.
The student communicates scientific
information with some
effectiveness.
When appropriate to the task, the
student partially documents
sources of information.
The student uses sufficient scientific
language correctly.
The student communicates scientific
information effectively.
When appropriate to the task the
student documents the sources of
information correctly.
Student Self-Assessment
 My work does not match requirements below.
 I used some scientific language.
 For most sections of the lab report I followed
most of the requirements listed on the task
sheet.
 I give some info for some of my sources.
 I used only scientific language.
 For each section of the lab report I followed
most of the requirements listed on the task
sheet.
 Source information is missing making it hard for
the reader to trace my sources
 I used clear, concise, scientific language.
 For each section of the lab report I followed
completely the requirements listed on the task
sheet.
 I correctly cite my sources of information in text
and with a Works Cited list.
Criterion E: Processing Data
Student’s Teacher’s
Opinion Decision
0
SWA MYP Descriptor

The student does not reach a standard
described by any of the descriptors given
below.

My work does not match the
requirements below.

The student collects some data and
attempts to record it in a suitable format.
The student organizes and presents
data using simple numerical or visual
forms.
The student attempts to identify a trend,
pattern or relationship in the data.
The student attempts to draw a conclusion
but this is not consistent with the
interpretation of the data.
The student collects sufficient relevant
data and records it in a suitable format.
The student organizes, transforms and
presents data in numerical and/or visual
forms with some errors or omissions.
The student interprets the data stating a
trend, pattern or relationship in the data.
The student draws a conclusion
consistent with the interpretation of the
data.
The student collects sufficient relevant
data and records it in a suitable format.
The student organizes, transforms and
presents data in numerical and/or visual
forms logically and correctly.
The student correctly interprets the data
stating a trend, pattern or relationship in
the data.
The student draws a clear conclusion
consistent with the correct
interpretation of the data and explains
it using scientific reasoning.

Some of my data is relevant and my
table is partly correct

I tried to make a conclusion.

My data is relevant and recorded in a
suitable way.
I try to organize and process the data.
My conclusion matches the observations.

1–2




3–4




5–6
Student Self-Assessment




 My data is relevant and my presentation
is logical and clear.
 I correctly interpret the data.
 In my conclusion I comment on the
reliability of my data through comparing
my results to what would be expected
from published data.
 I give a scientific explanation of my
conclusion.
Criterion F: Attitudes in Science
Student’s Teacher’s
Opinion Decision
0
1–2
3–4
5–6
SWA MYP Descriptor
 The student does not reach a standard
described by any of the descriptors given
below.
 The student requires some guidance to
work safely and some assistance when
using material and equipment.
 The student requires some guidance to
work responsibly with regard to the living
and non-living environment.
 When working as part of a group, the
student needs frequent reminders to
cooperate with others.
 The student requires little guidance to
work safely and little assistance when
using material and equipment.
 The student works responsibly with
regards to the living and non-living
environment.
 When working as part of a group, the
student cooperates with others on
most occasions.
 The student requires no guidance to
work safely and use materials and
equipment competently.
 The student works responsibly with
regards to the living and non-living
environment.
 When working as part of a group, the
student cooperates with others.
Student Self-Assessment









My work does not reach a standard
described by any of the descriptors
given below.
During the experiment I did not know
what to do.
I forgot safety routines such as wearing
goggles, standing up, etc.
During the experiment I asked
questions even though the answer to
the question was provided in writing
and orally beforehand.
I forgot safety routines such as wearing
goggles, standing up, etc.
I did not ask questions that had already
been answered in writing.
I knew what I was doing in the lab
I included safety precautions in my
report and followed all safety routines
responsibly during the experiment.
I worked well with classmates.