CLASSROOM COPY
CLASSROOM COPY
Lab-Properties of Solids/ Bond Types
Safety goggles must be worn at all times
Introduction: Groups of atoms are held together by attractive forces we call chemical bonds. Why are
chemical bonds important? The type of chemical bond that occurs in a molecule or substance in part defines
its properties. For example, consider sodium chloride (NaCl) and hydrogen chloride(HCl). Both substances
contain chlorine, but NaCl is the white solid crystalline substance sprinkled on French fries, and HCl is a foul
smelling gas (note: when this gas is dissolved in water, it forms a solution known as hydrochloric acid. This is
the acid that your stomach uses to digest food.)
How can this be if both materials have chlorine in them? The chemical bonding that takes place in NaCl is
different than that in HCl. This gives NaCl and HCl very different structures, appearances, and properties.
An ionic compound is formed when a metal loses an electron to a non-metal to form charged cations and
anions. The oppositely charged ions arrange themselves in a tightly packed, 3-D structure called a crystal
lattice. Another type of attractive force between atoms, covalent bonding, occurs when two non-metals
share electrons. Metallic bonding occurs between metal atoms. The valence electrons in a metallic bond are
free-floating and are shared between the metal atoms (the so-called “sea of electrons”).
Purpose: To investigate the physical properties of common solids and to see if a substance’s bonding type
has any relationship to its properties observed in the lab.
Materials:
Aluminum metal –Al
Sodium Chloride -NaCl
Sucrose -C12H22O11
Ice - H2O (s)
4 test tubes
1 test tube holder
Hot hands
Distilled water
Bunsen burner
Stir sticks
Well Plate
Conductivity tester
Mortar and Pestle
Procedure:
1. Place a small scoop of each substance in the well plate and test the conductivity of each
substance in it’s solid state. The conductivity tester will determine if the substance conducts
electricity. (Please make sure to turn off the device when finished.)
2. Add a few drops of distilled water to each well and record if the substance dissolves in water
or not- we call this solubility.
3. Test the conductivity of each substance in the well now that it is submerged in the water.
Record your results.
4. Place a small amount of each solid into a test tube. Using a test tube holder, place it over the
flame and melt it. Record the amount of time it takes to melt the ice. NOTE: The Bunsen burner
reaches over 1000◦ C. Some substances may not melt using the Bunsen Burner, therefore their
melting point is higher than 1000◦ C. STOP TIME AT THE FIRST SIGN OF LIQUID
5. Place each substance (one at a time) in the mortar and pestle. Grind up the substance and
record how brittle it is (how easily it breaks up). Wipe out the mortar and pestle with a paper
towel between each substance.
Data/ Observations:
Physical
Properties
Sucrose
C12H22O11
Ice
H2O (s)
Epsom Salt
(MgSO4)
Sodium
Chloride (NaCl)
Aluminum (Al)
Type of chemical
bond (based on
chemical formula)
Conductivity (solid)
Solubility
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Conductivity
(dissolved)
Melting Point
(time it takes)
Brittleness
(yes or no)
Calculations/ Analysis:
1. Summarize your lab results, complete the following table:
Properties
Substances with
IONIC bonds
Substances with
COVALENT Bonds
Substances with
METALLIC Bonds
Melting point
(high/ med/ low?)
Soluble in water
(yes/ no?)
Conducts electricity
(yes/ no?)
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WRITE ON THIS PAPER
Questions for Discussion:
1. In order for a substance to conduct electricity, it must have free-moving charged particles so that the
electricity (which is moving electrons) can flow.
a) Explain the conductivity results observed for sodium chloride in the solid state and in aqueous
solution (which means dissolved in water).
b) Use your knowledge of metallic bonding (or the information in the introduction of this lab) to
explain why metals conduct electricity.
c) You must choose between two potentially horrible options- explain which one you’d choose and
why based on this lab.
1) Sit in a bathtub filled with distilled water in which a hair dryer (that’s plugged in) has
been submerged.
2) Sit in a bathtub filled with salt water in which a hair dryer (that’s plugged in) has been
submerged
2. Ionic substances are brittle & metallic substances are malleable. Explain how the different bond types
lead to this characteristic.
Conclusion: Read back through the introduction and purpose of this lab and then write a 3 sentence summary
that highlights what you accomplished during this activity, your results, and any errors that were made.