Bonding Chemically
(Carolina Inquiries)
Introduction/Engage: (Read the following, write the questions and answer in
complete sentences)
1.
2.
3.
4.
5.
6.
Describe the structure of an atom.
What are valence electrons and why are they important?
Describe the different types of elements found on the periodic table.
What is the meaning of the word “bond”?
Is there more than one way the word “bond” can be used?
List some substances that you can think of that bond.
Vocabulary
atom, valence electrons, bonding, anion, cation, conductor,
electronegativity, insoluble, nonpolar, octet rule, polar, soluble, solute,
solvent, electricity, melting point, hardness, solubility, ionic bond,
covalent bond, Lewis Structures, molecule
Purpose: Investigate and summarize the properties of different types of bonding,
drawing Lewis Structures to represent the types of bonds present.
Equipment/Materials:
potassium chloride
dextrose
benzoic acid
sodium sulfate
sodium carbonate
10 Al weighing dishes
100-mL deionized water
pipet
conductivity tester
mini scoops
microwell plate
hand lens
hotplate
paper towel
stopwatch
battery
black water
Safety Considerations:
1. Wear goggles and apron.
2. Do not inhale chemicals, particularly the benzoic acid.
3. Do not touch the hotplate. Use tongs to remove the aluminum weigh dish.
4. Keep water away from electrical equipment.
Procedure: (see handout)
Data Tables: (use a ruler to draw; label each)
Data Table 1: Properties
chemical bond type melting point solubility conductivity appearance
potassium
chloride
Ionic
(KCl)
dextrose
Covalent
(C6H1206)
benzoic
acid
Covalent
(C6H5COOH)
sodium
sulfate
Ionic
(Na2SO4)
sodium
carbonate
(Na2CO3)
Ionic
Explain
Explain (Analysis): (copy each question, answer in complete sentences)
Read the Explain sheet on Ionic Bonds and Covalent Bonds
Part 1
1. Examine the data collected for melting point. What conclusions can you draw
about the melting point of these chemicals?
2. Which substances have higher melting points? Which have lower melting
points? What does this indicate about the bonds in the substances?
3. Summarize the solubility of the substances in the Explore Activity.
4. How is solubility associated with the type of bond present?
5. What does the solubility of the different substances indicate about the type of
bond present?
6. How is conductivity related to the type of bond present?
7. Why do substances with certain types of bonds conduct electricity well, while
some substances are not good conductors?
8. Is there a significant difference in appearance between the substances with
covalent bonds and those with ionic bonds? What properties did you notice
you could not see with the naked eye?
9. Imagine looking at the substances under a microscope. What do you think the
substances might look like on a microscopic level?
Part 2
Draw Lewis structures for the following ionic compounds.
1. NaCl
2. MgO
3. LiF
Draw Lewis structures for the following covalent compounds.
1. H2O
2. CO2
3. NH4
Bonding Chemically (Carolina)
Procedure:
1. You should have 2 separate, labeled weighing dishes of each of the following:
potassium chloride, dextrose, benzoic acid, sodium sulfate, sodium carbonate
-one dish will be used to test melting point
-one dish will be used for the remaining tests
2. Record your data in Data Table 1. You data will be qualitative, so exact
measurements are not required.
Test 1: Melting Point
1. Using tongs, place an aluminum weigh dish containing one chemical on a heated
hotplate. You might be able to place more than one at a time.
2. Use the stopwatch to time how long it takes each chemical to melt. Record the time. If it
does not melt after several minutes, note that it has a high melting point.
3. Using tongs, remove the weigh boat(s) from the hotplate.
4. Repeat for each sample.
Test 2: Solubility
1. Using the pipet, drop 2mL of deionized water into wells A1-A6 of the microwell plate.
2. Place ½ of a mini-scoop of potassium chloride in Well A1. Stir gently using the miniscoop, if necessary. If it dissolves, record ‘soluble’ in the Data Table. If it does not
dissolve, record ‘insoluble’.
3. Rinse the scoop with clean deionized water and dry it with a paper towel.
4. Repeat this process for all remaining substances, leaving well A6 alone (it is a control).
Test 3: Conductivity
1. Test the conductivity of each solution, by placing the ends of the conductivity tester into
each ‘well’. Be sure to rinse between testing the different substances.
2. If the LED lights up, record ‘Yes’. If it does not light up, record ‘No’.
3. Be sure to test well A6.
Test 4: Appearance
1. Record the appearance of each substance. Keep in mind the following:
a. Appearance to the naked eye
b. Appearance using a hand lens
c. Noticeable difference between the substances
d. Similarities between the substances
e. Identify color, texture, particle size and shape, any other physical properties
2. Clean up.