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LAB: CHEMICAL FAMILIES
SCH 3U
The Search For Trends and Patterns in the Periodic Table
Purpose
To observe relationships between the reactivity of elements and their location on the periodic table.
Note: Phenolphthalein (phth) is an indicator. This particular dye is used to test solutions to see if they
are acidic or basic. In basic solutions, it turns pink and in acidic solutions it is colourless. Red and blue
litmus papers are also indicators used in testing solutions for acidity or alkalinity. Red litmus turns blue
in basic solutions and blue litmus turns red in acidic solutions.
Pre-lab Questions
After reading the lab, answer the following questions using complete sentences. Provide examples, and
diagrams when applicable. Try to incorporate all of the new scientific terminology into your answers.
1. Describe at least three safety issues that you as the experimenter must be aware of when conducting the
lab.
2. What is phenolphthalein and what is it used for.
3. Draw the Bohr-Rutherford diagrams for the alkali metals, alkaline Earth metals and aluminum that will
be used in this lab.
4. Write out the full electron configuration for the transition metals that will be used in the lab.
Based upon your prior knowledge of periodic trends (atomic radius, ionization energy), predict the
trend of reactivity for the metals studied in this lab.
Hypothesis:
If you move down a group then the reactivity of the metal will increase because________________
As you go across a period the reactivity of the metal will ___________ because ___________________
Materials & Apparatus
samples of Li, Na, K , Cu, Mg, Ca, Ba, Fe , Zn, Al
phth, red and blue litmus papers
beakers
wire gauze
tea light and splint
watch glass
scoopula, grad cylinder
test tubes, test tube rack,
0.5 M HCl (aq)
Safety:
K, Ca, Na, and Li are highly reactive. Do not touch these metals with your hands.
Hydrochloric acid is an irritant. Wash any spills on skin or clothing immediately with
plenty of cold water. Report any spills to your teacher. Tie back long hair and secure loose
clothing.
Procedure Part One: Reactivity of Metals in Water
1. Watch carefully as your teacher cuts pieces of each of the metals.
2. In the chart provided, note your observations regarding the physical properties colour, lustre, malleability
and hardness of each of the metals. Record the results in the chart.
3. Carefully place the pieces of each metal for part A (Li, Na, K, (alkali metals complete one at a time) Mg, Ca,
Cu) onto a watch glass and return to your lab station.
4. Starting with lithium, half fill a beaker with water and carefully place the lithium using your scoopula, in the
water. Stand at arm’s length from the beaker. Place the wire gauze over the top of the beaker and record
your observations of the reaction.
5. When the reaction appears to be complete, remove the wire gauze and dip your fingers in the liquid and
record the feeling.
6. Dip a piece of blue and red litmus paper into the solution and record your results. *Put the paper in the
garbage. **
7. Add 3 drops of phth solution to the beaker and record your results.
8. Repeat steps 5 through 8 with sodium, magnesium, (*clean the Mg strip with steel wool), calcium and copper.
Potassium and barium will be done by your teacher (teacher demo).
9. Clean and dry all equipment before proceeding to part two.
Procedure Part Two: Reactivity of Metals in Hydrochloric Acid
1.
Measure out 20.0 mL of dilute hydrochloric acid. Pour 5.0 mL into each of five clean test tubes in your test
tube rack.
2.
Obtain small quantities of magnesium, iron, zinc, calcium and aluminum.
3.
Record the physical properties of each of the metals. One at a time, carefully drop each of the metals into a
different test tube of hydrochloric acid.
4.
Observe over a 20 min. period. Occasionally feel the test tubes with your hand to find out if they get warmer
as any reaction proceeds. Record your observations.
5.
If you observe bubbles, collect a sample of the gas by covering the test tube loosely with a rubber stopper.
While the test tube is in the test tube rack, test the resulting gas by removing the stopper and quickly holding
a glowing splint just inside the mouth of the test tube.
6.
Recycle or dispose of any waste according to your teacher’s instructions.
Observations (Separate sheet)
Analyze and Evaluate
1. Sort the elements that you tested into groups according to their reactivity and compare this to the periodic
table. State the apparent order of reactivity as one proceeds down a group. Does the reactivity increase or
decrease? Provide a rational as to why you observed the trend. (You should include examples, diagrams ie.
Bohr-Rutherford or electron energy level diagrams etc...)
2. Physical & chemical properties of the groups.
a) From your observations, what physical properties do the elements in each of your groups have in
common?
b) From your observations, what chemical properties do the elements in each of your groups have in
common?
3. Is the solution that is produced when a metal reacts with water acidic or basic?
4. Rank the elements in Part B from least reactive to most reactive.
5. Based upon your gas test results, what gas was produced when the metals reacted with the acid?
6. Does the reactivity increase or decrease as one moves across a period. Provide a rational as to why you
observed the trend. (You should include examples, diagrams i.e. Bohr-Rutherford or electron energy level
diagrams etc...)
7. Evaluate this investigation. Did the design enable you to collect enough evidence to decide whether to accept
or reject your hypothesis? How could it have been improved? Would your suggested improvements raise any
safety concerns?
Apply and Extend
8. Extrapolation of properties.
a)
Predict the properties of Rb, Cs and Fr in group 1 relative to the ones you’ve studied.
b)
Predict the properties of Be, Sr and Ra in group 2 relative to the ones you’ve studied.
c)
Give two reasons why the alkali metals are stored in oil.
9. Connect the trends observed in Parts A and B to atomic radius, ionization energy, and electron affinity. Write
a paragraph to explain the trends. Be sure to include relevant examples, diagrams and appropriate scientific
terminology.
Question #10, 11 are the only questions you are to submit. Hand in one copy per group. All
other questions will be discussed in class and then those concepts will be applied when you
design your own lab!
10. Select two careers related to atomic structure, that you find interesting. (May or may not be listed below)
Research the educational pathways that you would need to follow to pursue these careers.
e.g. SCH3U  SCH4U OSSD  Bachelor of Engineering  Electrical engineering give specific Canadian
examples
What is involved in the required educational programs? Prepare a brief paragraph of your findings. Be sure to
include Canadian examples…..
a.
b.
c.
d.
e.
f.
g.
h.
i.
agronomist
nutritionist
chemical engineer
radioisotope lab technician
home inspector
pollution control technologist
nuclear chemist
particle research chemist
radiologist
11. For one of the two careers that you choose above, describe the
-career,
-main duties and responsibilities,
- working conditions, and setting.
Also outline how the career benefits society and the environment.
**For questions 10, 11 you must include references MLA or Chicago or APA style, thus including a
bibliography as an appendix to your assignment
Observations
Table #1 Observations for the reactivity of metals in water
element
Li
Na
K
Mg
Ca
Ba
Cu
colour and
lustre
malleability and
hardness
reaction with
H20
feel of solution
Litmus results
phth results
rate of reaction
1st, 2nd, 3rd, 4th
Table #2 Observations for the physical and chemical properties of various metals
element
symbol
colour and lustre
malleability and
hardness
results of gas test
Mg
Fe
Zn
Al
Any additional observations/comments/modifications to the procedure:
reaction with
0.5 M HCl (aq)
feel of solution
endothermic/exothermic
/stays same
rate of reaction
1st, 2nd, 3rd, 4th