NAME:_____________________________________________________ DUE:_______________ ASSIGN #: _______
Periodicity of Metals-Alkaline Earth Metals
Purpose:
After conducting this lab, can you write a short paragraph describing the purpose of this lab? This
paragraph should start your lab report followed by the post lab questions, which are below. Of course, it
should be typed and it will be worth 5 points.
Materials:
Bottles with each of the following chemicals:




magnesium nitrate solution – Mg(NO3)2
calcium chloride solution – CaCl2
strontium nitrate solution - Sr(NO3)2
barium nitrate solution - Ba(NO3)2



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potassium chromate solution – K2CrO4
ammonium sulfate solution – (NH4)2SO4
sodium carbonate solution - Na2CO3
potassium oxalate solution - K2(C2O4)
Spot plates/reaction plates, safety glasses, wash bottle to clean spot plate
Safety:
Wear safety glasses, aprons, long pants, and closed-toe shoes. Failure to have appropriate safety gear will
lead to sitting this lab out and a zero on the lab. Ammonia compounds can be irritating to eyes and
respiratory tract. Potassium chromate is corrosive to skin, eyes, and respiratory tract. Nitrates are strong
oxidants and a potential fire risk when in contact with organic material. Strontium and barium compounds
are toxic by ingestion. Oxalates are toxic by inhalation and ingestion.
All spot plates should be rinsed with water into waste jug, which is in chemical hood.
Procedure:
1) Set up a spot/well plate as shown in Figure 1 (you will need to use two spot plates) on backside of this
sheet. Each reaction well will receive one drop from each chemical. For instance, the top left well will
receive one drop of magnesium nitrate and one drop of potassium oxalate. The bottom right well will
receive one drop of barium nitrate and one drop of potassium chromate.
2) As you add your drops, make note on Figure 1 of which wells show reactions along with any
observations. (1 pt each). If the well stays clear, a reaction most likely did not occur.
3) Look for patterns in the data. Think about trends in the periodic table and what the data is telling you.
If you figure this part out, you will have a good idea of what the purpose of this lab was.
4) Rinse your spot plate with water into the waste jug, which is in the chemical hood.
NAME:_____________________________________________________ DUE:_______________ ASSIGN #: _______
Chemical
potassium
chromate
K2CrO4
ammonium
sulfate
(NH4)2SO4
sodium
carbonate
Na2CO3
potassium
oxalate
K2(C2O4)
(use 2nd spot plate)
magnesium
nitrate
Mg(NO3)2
calcium
chloride
CaCl2
strontium
nitrate
Sr(NO3)2
barium nitrate
Ba(NO3)2
Figure 1
PostLab Questions: (Type on a separate sheet of paper)(Answer in complete sentences, except #1)
1) The group II metals are commonly known as the ________________ metals. (1 pt)
2) List any observations you saw that provide evidence of a reaction. (1 pt)
3) Describe any patterns or trends you saw when looking at your data table. (1 pt)
4) Based on which metals seemed relatively more reactive, how does reactivity change as you go from top
to bottom in Group 2 of the periodic table? (1 pt)
5) If you wanted to find a more reactive metal than barium, should you move one element to the left or to
the right of barium on the periodic table? Explain your reasoning by using the electron configuration of
barium when compared to the more reactive element. (2 pts)
6) What would happen if you mixed beryllium nitrate with potassium chromate, ammonium sulfate,
sodium carbonate or potassium oxalate? Would you expect a reaction with any of these four
compounds? Explain your results in terms of the data you collected in this lab. (2 pts)
7) Read about ionization energy trends seen in the periodic table (page 173-174). Use this information to
explain the pattern you saw in reactivity of Group 2A metals. (2 pts)
Real-World Application:
8) Pescadero Creek is suspected of being contaminated with pollution from the local quarry. Rumor has it
that the culprit might be a dangerous, radioactive compound, known as radium nitrate. Based on this
experiment, describe a chemical test that you can run to detect radium nitrate. Also, what results would
you expect from your experiment if radium nitrate is present? What results would you expect if radium
nitrate is not present? (3 pts)
More reading on radium nitrate contamination –
http://nj.usgs.gov/publications/FS/fs-062-98.pdf
http://knightnews.com/2012/06/30/opinion-ucf-drinking-water-may-be-a-risk/