Name: ___________________________________ Date: ___________________ Period: ______
Periodic Trends of Alkali and Alkaline Earth Metals
Purpose: To show that elements in the same group on the periodic table show similar
trends in solubility and reactivity.
Part 1: Solubility
In this part of the experiment, you will compare the solubility of compounds made
from alkali metals to compounds made from alkaline earth metals.
Materials:
Four large test tubes
Test tube rack
150ml of distilled water
Sodium Carbonate (Na2CO3)
Potassium Carbonate (K2CO3)
Calcium Carbonate (CaCO3)
Magnesium Carbonate (MgCO3)
Procedure:
1. Place about 1 gram (size of a pea) of each of the four compounds into separate
test tubes.
2. Fill the test tubes about ¾ full with distilled water and stir with a stirring rod.
3. Rinse the stirring rod with distilled water.
4. Stir each solution very well for several minutes.
5. Observe the test tubes and answer the following question.
a. Which 2 compounds are made from alkali metals?
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b. Which 2 compounds are made from alkaline earth metals?
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c. Define the word soluble: _______________________________________
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d. Which compound is most soluble?________________________________
e. Which compound is least soluble? _______________________________
f. In general, which are more soluble, compounds made from alkali metals
or alkaline earth metals? _______________________________________
Clean Up: All used contents of the test tubes may be rinsed down the sink with water.
Clean all test tubes and laboratory material thoroughly to prevent cross contamination of
chemicals.
Name: ___________________________________ Date: ___________________ Period: ______
Part 2: Periodic Trends in Alkaline Earth Metals
In this part of the experiment you will observe trends in reactivity of the alkaline
earth metals. In this case, reactivity will be seen in the metal’s ability to form a
precipitate in a reaction. More reactive metals are more likely to produce more
precipitate.
Materials:
Magnesium Nitrate Solution: Mg(NO3)2
Strontium Nitrate Solution: Sr(NO3)2
Barium Nitrate Solution: Ba(NO3)2
Calcium Nitrate solution: Ca(NO3)2
Potassium Chromate Solution: KCrO4
Ammonium Sulfate Solution: (NH4)2CO3
Ammonia Solution: NH4
Ammonium Carbonate Solution: (NH4)2CO3
Well Plate
8 Droppers
Procedure:
1. _____ Place about ½ a dropper full of magnesium nitrate into each of 4 wells in
the same row of the well plate.
2. _____ Repeat step 1 with calcium nitrate in the next row of 4 wells.
3. _____ Repeat step 1 with strontium nitrate in the next row of 4 wells.
4. _____ Repeat step 1 with barium nitrate in the next row of 4 wells.
5. _____ Add about ½ a dropper full of potassium chromate solution to the first well
only of the magnesium nitrate row.
6. _____ Repeat step 5 for the remaining three rows. Make sure you add the
solution only to the first well of each row.
7. _____ Add about ½ a dropper full of ammonium sulfate solution to the second
well only of the magnesium nitrate row.
8. _____ Repeat step 7 for the remaining three row. Make sure you add the solution
only to the second well of each row.
9. _____ Add about ½ a dropper full of ammonia solution to the third well only of the
magnesium nitrate row.
10. _____ Repeat step 9 for the remaining three rows. Make sure you add the
solution only to the third well of each row.
11. _____ Add about ½ a dropper full of ammonium carbonate solution to the fourth
well only of the magnesium nitrate row.
12. _____ Repeat step 11 for the remaining three rows. Make sure you add the
solution to the fourth well of each row.
13. _____ Observe and record your observations in the table below.
Name: ___________________________________ Date: ___________________ Period: ______
Data: Record your visual observations below.
KCrO4
(NH4)2SO4
NH3
(NH4)2CO3
Mg(NO3)2
Ca(NO3)2
Sr(NO3)2
Ba(NO3)2
Note: After all of the test solutions have been added, observe the patterns in the way
that precipitates have formed. You should see that one of the alkaline earth metals
always produces a lot of precipitate, and one that usually produces only a little.
Clean Up: Barium and chromate cannot be rinsed down the sink. Pour the used
solutions in the well plate into the beaker provided. Use a wash bottle to rinse it into the
beaker. Clean the rest of the well plate down the drain and wash the remaining
equipment with water.
Name: ___________________________________ Date: ___________________ Period: ______
Questions: Answer the following questions. Your answers should be based on your
observations from part 2.
1. Which alkaline earth metal produced the most precipitate almost every time?
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2. Which alkaline earth metal produced the least precipitate almost every time?
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3. Rank all four alkaline earth metals, from least to most, in amount of precipitate
formed:
a. ___________________________
b. ___________________________
c. ___________________________
d. ___________________________
4. Compare your ranking in question 3 to the order that the alkaline earth metals
appear in the periodic table, what do you notice? _________________________
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5. In general, as you read down the column of the periodic table, are alkaline earth
metals more or less reactive? Why? ___________________________________
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6. How does this activity demonstrate that elements in the same group (column) in
the periodic table have similar properties? (Hint: What physical property was
observe in part 1 and what chemical property was observed in part 2?)
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