Periodic Behavior of Metals
Objective
To rank several metals in a reduction activity series that shows their relative reactivities with hydrogen ion and to correlate
their position in the series with some of their periodic properties.
Introduction
Why do some metals dissolve readily in acid and others not? A more knowledgeable form of the same question is, why do
some metals donate electrons to hydrogen ions more readily than others?
The reaction of metals with hydrogen ions to produce hydrogen gas is an oxidation-reduction reaction in which H+ receives
an electron from a metal and is reduced to elemental hydrogen. The elemental metal is oxidized to the corresponding
cation. Whether or not this occurs depends on the relative attractions of the metal and H + for the electron. The relative
reactivities of different metals with H+ is a measure of their relative reducing strengths. The more vigorous the reaction
with H+, the higher the metal ranks in the reduction activity series.
Some metals will not react with hydrogen ion at all. This means that they hold their electrons so strongly that hydrogen ion
cannot take them. Such metals are said to be less active than hydrogen and are ranked below hydrogen in the reduction
activity series. To rank these less active metals, stronger oxidizing agents than hydrogen ion must be used, but we will not
do that in this experiment.
As part of this experiment, you will try to determine what periodic properties of the metals are most closely related to their
reducing strengths. Table 0.1 contains values for periodic properties that might be expected to be related to a metal’s
reducing strength.

Metal
Ag
Al
Ca
Cu
Mg
Mn
Ni
Pb
Zn
st
nd
rd
1 IE
(kJ/mol)
2 IE
(kJ/mol)
3 IE
(kJ/mol)
731
578
590
746
738
717
737
716
906
2070
1817
1145
1958
1451
1509
1753
1450
1733
3361
2744
4912
3555
7732
3248
3395
3082
3833

and 2nd
IE
st
1339
1239
555
1212
713
792
1016
734
827
2nd
and 3rd
IE
1291
927
3767
1597
6281
1739
1642
1632
2100
Electronegativity
(Pauling scale)
Covalent
Atomic
Radius
(pm)
Ionic Radius
(pm)
1.93
1.61
1.00
1.90
1.31
1.55
1.91
2.33
1.65
152
143
197
135
160
139
121
175
120
129 (Ag+)
67 (Al3+)
99 (Ca2+)
91(Cu2+)
86 (Mg2+)
80 (Mn2+)
83 (Ni2+)
133 (Pb2+)
88 (Zn2+)
Table 0.1 Some Periodic Properties of Selected Metals
Plan of the Experiment
Nine metals are to be tested: Ag, Al, Ca, Cu, Mg, Mn, Ni, Pb, and Zn. Some of them react violently with 1 M HCl and
some not at all. The most reactive metals will react even with cold water, in which the hydrogen ion concentration is only
about 1  10–7 M, and this is how you will identify these very reactive metals. The overall general reaction of a metal
(indicated by M) with water is:
M(s) + n H2O  M(OH)2 + (n/2) H2(g)
equation 1
Metals that show no perceptible reaction with cold water will be tested next with hot water, which speeds up the reaction
rate. Metals that show no reaction with cold or hot water will then be reacted with cold HCl.
Finally, the least reactive metals, which have not reacted with water or cold HCl will be tested with hot HCl.
When you finish, you may have several metals that have not reacted at all, even with hot HCl. Group these together at the
low end of your reduction activity series, taking care to note any other changes, such as in temperature or in color.
The net ionic equation for the reaction of any metal with HCl is:
M(s) + n H+  Mn+ + (n/2) H2 (g)
equation 2
Caution! Combining highly reactive metals with hydrochloric acid is dangerous. Hydrochloric acid may cause
chemical burns. Calcium metal may also casue chemical burns.
Procedure
1.) Fill a 400 mL beaker 2/3 full of water and heat it to near boiling. It will be used as a water bath for various
samples throughout the experiment. Try to maintain the temperature just below the boiling point. Refill the bath
during the experiment when too much water has boiled away.
2.) Obtain powdered or granular samples of the following metals:
Al, Ca, Cu, Mg, Mn, Ni, Pb, Zn
3.)
Test each metal, except aluminum, by putting a small amount of each in large labeled test tubes containing about
5 mL of cold distilled water. Observe whether any bubbles of H2 form. Record which metals react, ranking them
in order of most vigorous reactivity.
4.) Aluminum requires special treatment to remove its thin film of oxide before it can be tested.
a.) Put about a centimeter of Al in a large test tube with 2 mL of H2O and 2 mL of 6 M HCl.
b.) Heat the test tube and contents in the water bath for a few minutes until a vigorous reaction is observed.
Immediately remove the test tube and quickly add about 10 mL of cold distilled water to dilute the acid
solution, then decant the diluted acid into a waste beaker.
Caution! Do not allow the acid/aluminum mixture to boil. Doing so will may cause the mixture to erupt, and this may
burn your skin. It will certainly make quite a mess to clean up.
5.)
6.)
7.)
8.)
9.)
10.)
c.) Wash the Al granules twice as follows: fill the test tube half full with distilled water, decant most of the
water into the waste beaker leaving enough water to completely cover the metal pieces. Repeat the
washing.
d.) Observe whether Al reacts with the cold water remaining in the test tube. Record your observations and
rank aluminum in the cold water reactivity series.
For only those metals that do not react or react very weakly with cold water, place their test tubes in the hot water
bath. Observe whether bubbles form and record the results, again ranking the metals by the vigor of reaction.
Using only the metals that have not yet reacted, pour off all but about 2 mL of water and add 2 mL of 6 M HCl.
Watch for three minutes, if necessary, for signs of reactivity. Record the relative bubbling rates.
For any metals that did not react with cold HCl, place their test tubes containing cold HCl in the hot water bath
(not quite boiling) and watch for any reaction. Record the relative bubbling rates.
In your Lab Notebook, arrange the metals in order of reduction activity, putting the most reactive first. Group all
completely non-reactive metals together at the end of the list.
Your TA will test silver (it’s too expensive for everyone to test!) and will report the results to the class.
Using Table 1, try to find the periodic property that correlates best with your reduction activity series. Plot the
value of the periodic property on the vertical axis and the ordered list of metals on the horizontal axis. Do not
look for an exact correlation because many other factors may influence reactivity. Look for the periodic property
that shows the best correlation. Use your knowledge of chemistry to provide an explanation for the correlation
you observe. Why does one property fit better than the others?