Metallic Character and Periodic Trends Lab
Name _______________________________
PSI Chemisitry
Purpose:

Study the reactivity of three metals.

Predict an order for the relative reactivities of three metals based on experimentation
and knowledge of periodic trends.
 Demonstrate the “alkaline” properties of alkali and alkaline earth metals.
Introduction:
Most metallic elements exhibit shiny luster, conduct heat and electricity and are malleable and
ductile. The relative metallic character can be predicted using the element's reactivity, their
electron configurations and knowledge of the periodic trend, effective nuclear charge, Z eff.
Zeff = Z - S
In this formula Z equals number of protons in the nucleus (the atomic number) and S equals
the numbers of core electrons in an atom.
Alkali and alkaline earth metals produce basic solutions when mixed with water. This can be
tested using an indicator (phenolphthalein) that turns a pink color when in basic solution.
Pre lab Activity:
1. For each of the following elements write the noble gas electron configuration and
calculate the effective nuclear charge.
Metal
Noble gas
electron configuration
Zeff = Z - S
Ca
Mg
Al
2. How does an element with an effective nuclear charge of 1 compare with an element
with an effective nuclear charge of 2 in terms of metallic character?
Materials:
Calcium metal
Magnesium metal (ribbon form)
Steel wool
Aluminum foil
water
evaporating dishes (3)
tongs
bunsen burner and lighter
phenolphthalein indicator, litmus paper, or pH
paper
watch glass (3)
goggles and aprons
Procedure: PART A: Examining reactivities of metals with water.
1. In this lab we will be examining the relative reactivities of Mg, Ca, and Al. Based on what
you know of metallic character, which of these would you expect to be most metallic and
therefore most reactive? _______ Justify your answer:
2. Of the remaining two, which would you expect to be the least reactive, least metallic of the
pair? _______ Justify your answer:
3. Your ranking from most to least metallic/reactive is ______> _______>________.
4. Fill 1 evaporating dish 1/3 full with water. Using tongs, add a small piece of calcium metal
from your teacher into the water and then cover the evaporating dish with the watch glass.
Record your observations in Table A. If the reaction stops and some calcium remains, use a
squirt bottle to add more water gently until the calcium has disappeared.
5. Remove the watch glass and add 5 drops of phenolphthalein solution. Record observations
in table A.
6. Perform the same steps with small pieces of magnesium and aluminum metal in respective
evaporating dishes. Record observations in table A. Do not waste any time adding water to
these dishes to “finish the reaction”.
Table A
Metal
Calcium
Reaction with water
Addition of
Phenolphthalein
Magnesium
Aluminum
PART A: Analysis
1. Which metal proved to be the most reactive? ________ Was this what you expected?
2. What observation confirmed calcium’s labeling as an alkaline earth metal?
3. Was there any indication from this experiment that magnesium is an alkaline earth metal?
________ Explain:
Procedure (Part B): Examining reactivity of metals with oxygen.
1. In this experiment, we will perform an experiment to determine the difference in reactivity of
Mg and Al.
2. As a reminder, which of these two metals do we expect to be the most metallic? _______
Justify your answer in terms of effective nuclear charge:
3. Scrap your magnesium with steel wool to remove any pre-existing magnesium oxide that
may exist on your magnesium.
4. Light the bunsen burner and using the tongs hold the piece of magnesium in the flame until
it ignites. It will burn with a bright light. (DO NOT LOOK DIRECTLY AT IT). When the light
dissipates, remove what is now magnesium oxide from the flame. Observe the magnesium
strip and record in table B. Then place it into a water filled evaporating dish and add
phenolphthalein. Make observations.
5. Perform the same steps with the aluminum foil strip - except don’t wait for a bright flash.
Heat for the same amount of time as the magnesium strip.
Table B
Metal
Magnesium
Reaction with oxygen in flame
Addition of
phenolphthalein
Aluminum
PART B: Analysis
1. Which of the two metals was more reactive? _______ Is this what was expected? ____
Explain:
2. List the metals, Ca, Mg and Al, in order of greatest metallic character to least metallic
character.
3. When phenolphthalein is added to a basic solution it turns pink. The words basic and
alkaline are often used interchangeably. Which of the metals you observed today could be
called alkaline?