Periodic Trends and the Properties of Elements
The Alkaline Earth Metals
Purpose
The gurpose of this experiment is to identif,z periodic trends in the
activitv and solubiliqv of the alkaline earth metals.
Equipment
Chemicals
Aluminum foil, Al, 2-cm square, 2
Barium chloride, BaClz,0.1 M, 3 mL
Calcium, turnings, Ca, 2 pieces
Calcium chloride, CaCl2,0.L M, 3 mL
Magnesium ribbon, Mg, 1-cm piece,2
Magnesium chloride, MgCl2, 0.L M, 3 mL
Strontium chloride, SrCl2, 0.L M, 3 mL
Unknown metal chloride solution, 0.L M, 3 mL
Water, distilled or deionized
Hydrochloric acid, HCl, 0.5 M, 3 mL
Potassium iodate, KlO3, 0.2 M, 5 mL
Sodium carbonate, Na2CO3, 1- M, 5 mL
Sodium sulfate, NazSO+, 1 M, 5 mL
Matches (optional
Litmus paper, red, 3 pieces
er, white, l- sheet
Pipets, Beral-tvpe, l-0
Reaction plate, 24-well
Thermometer
Introduction
Elements that share similar properties are assembled together in vertical columns
identified qs groups or families on the period toble. Beryllium, magnesium, calcium,
strontium, barium, and radium are a reactive group of metals in the Alkaline earth metals
family. Knowing hsvt fast or how vigorous a metal reacts makes it possible to rank the
metal in orderfrom most active to least active. The activity series of metals shows clear
periodic trends both within a group and across a period of elements in the periodic table.
Chorlinda Chheng
Lab Team #5
Period 8
121310
Procedure
Part A. ActiviQ of Metals
1. Obtain 2 small pieces of calcium turnings and place them in a
weighing dish or small beaker.
2. Obtain 2 small pieces of magnesium ribbon, have the ribbons be
approx. 1-cm each; Also obtain a short piece of aluminum foil.
3. Now prepare a sheet of white paper to place a 24-well reaction
plate on top of.
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4. Using a pipet add 20 drops of distilled water to wells labeled A1-A3
5. with a piece of red litmus paper test the water in wells ,A1-A3 and
record the initial color for this "litmus test" in Data Table A.
6. carefully pick up one piece of calcium with a pair of forceps to add
to well 41.
7. Use the forceps again to add one piece of magnesium ribbon to
well A2.
8. Analyze and observe each well and record all immediate reactions
in Data Table A. lf no changes are observed in a particular well, write
NR (No Reaction) in the data table.
9. Repeat step 5 and record the color changes.
10. Keep watching each well for 1-2 minutes. Record any additional
observations comparing the rafes of reaction in Data Table A.
11. Add 20 drops of 0.5 M HCI with a pipetto wells C1-C3. Measure
the original temperature of the solutions in well C1-C3 and record the
degrees as "observation" in Data Table A.
12. Carefully pick up one piece of calcium with a pair of forceps to
add to well C1.
13. Use the forceps again to add one piece of magnesium ribbon to
well C2.
14. Obtain a piece of aluminum foil and add the aluminum metal to
well C3.
15. Observe each well and record all immediate reactions made into
Data Table A. lf no changes occur write NR in the data table.
16. Use a thermometer to measure the temperature of each solution
in wells C1-C3. Record the temperature each solution has produced
in Data Table A.
17. (Optional) lf gas becomes present in wells C1-C3, test the
combustion property of gas by bringing a lit match to the space just
above the wells C1-C3. Record all observations for this "match test"
in Data Table A.
18. Keep watching each well for 1-2 minutes. Record any additional
observations comparing the rafes of reaction in Data Table A.
19. Dispose the well contents as instructed by your teacher. Be sure
to rinse the reaction plate with distilled water before using the plate
again in Part B.
Part B. Solubility of Alkaline Earth Metal Compounds
20. Put the 24-well reaction plate on top of a sheet of white paper.
21. Refer to Data Table B as a guide, using a pipet add 20 drops of
alkaline earth metals solutions to the appropriate wells.
22. Use a clean pipet to add 20 drops of the unknown alkaline earth
metal solution into wells A5-C-5
23. Refer to Data Table B as a guide, using a clean pipet add 20
drops of testing solution to the appropriate wells.
24. Record any observations in Data Table B. lf a solid forms, write
PPT (precipitate) in the appropriate circle in the data table. lf no solid
forms, write NR (no reaction) in the appropriate circle in the data
table.
25. Dispose the contents in the reaction plate as instructed by your
teacher.
Observations and Data
Data Table A. A"tit'ity of Metats
Calcium
Solution
bubbles,
ftzzes,
foams, and
Observations
Reaction
with H,0
[Before]
Litmus Test
Magnesium Aluminum
Some slight
bubbling seen
on surface of
Mg metal
smokes.
Metal is
gone;
replaced by
crumbly
white solid.
Final
Mixture is
cloudy,
milkv white
Changes from
Red;
To blue
NR
No Change
No Change
Red
Red
Solution
bubbles, frzzes.
Gas given off.
2s.4 C.
No Reaction.
25.4 C.
Temp increases
from -20
Degrees C. 35 Degrees C.
34.5 C.
27.1 C.
No
No
IAfter]
Temp.
Reaction
[Before]
Observations
with HCI
IAfter]
Match Test
(optional)
Solution
bubbles, frzzes,
foams, smokes,
and boils!
Almost out-ofcontrol. 25.4 C.
Metal
disappears; final
mixture is
chalky white.
36.3 C.
Large "pop" and
flame goes out.
Yes
Data Table B.
Sol,,bitity of Alkaline Earth Metal Compounds
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Questions and Problems
Q. Which group IIA metal, magnesium or calcium, is more active? Cite your
evidence.
A. Calcium was more reactive. Calcium foamed, smoked, and produced
gas.
It also produced much more heat.
a Wich period 3 metal, magnesium or aluminum, is more active? Cite
your evidence.
A. Magnesium and Aluminum did nothing (no reaction).
But,
Magnesium did have a change in temperature.
Q. Rank the three metals tested in Part A from most active to least active.
A. Calcium, Magnesium, then Aluminum.
A
Write the general statement that describes the periodic trend in metal
activiQ across a group (vertical column) of the periodic table.
A. As you go down a family reactivity goes up.
I
Q. Write a general statement that describes the period trend in metal activiQ
within a period (horizontal row) of the periodic table.
A. As you go from left to right across a periodo reactivity goes down.
Q. Locate the following metals on the period table: magnesium, potassium,
and sodium. Based on your qnswers to Questions #4 and 5, rank these
metals in order of their expected activity, fro* most active to least active.
A.K>Na>Mg
Q. Litmus paper changes color in acidic (red) and basic (blue) solutions.
The word alkaline is a synonymfor basic. Wy are the two words "alkaline"
end "earth" used to name the Group IIA metals?
A. Alkaline also meaning basic is based on H20, which is also the surface
of the earth.
Q. In Part B, which alkaline earth metal formed the most precipitates? The
fewest?
A. Ba formed the most and Mg formed the least reaction.
Write a generol statement that describes the periodic trend
solubility of alkaline earth metal compounds.
A. Mg= Ca> Sr> Ba
a
in the
Q. Use the solubiliQ pattern observed for the lcnown and unlcnown alkaline
earth compounds in Part B to deduce the identity of the unknown alkaline
earth metal.
A. Calcium is the unknown
Results
In this lab our data agreed with the family/period reaction trend. As we went
down a family the reactivity went up. As we went across a period (left to
right) reactivity went down. Our data also followed the activity trend. As we
went down a family, (Alkaline Earth Metals) the solution/compounds
became more reactive.