GROUP/PERIODIC PROPERTIES LAB
Purpose: To observe cool chemistry and deduce reactivity trends.
Procedure: Make a data table that includes the name of each of the following tests, lists
the chemicals used in the test, states what the chemicals look like before the reaction,
what the reaction looks like, what the chemicals look like after the reaction, and whether
the products are acidic or basic.
Test #1: Combustion of Sulfur
Go to the fume hood with a 250 ml flask with 50 ml of water in it.. Put a pinch of sulfur
into a conflgurating spoon and do as your instructor demonstrated with phosphorus.
First, start the sulfur burning with by holding the spoon in a burner flame. Then, insert
the burning spoon into a 250 ml flask that has 50 ml of water in it. After the sulfur
extinguishes, stopper the flask and shake to get the combustion gases dissolved in the
water. Test for acid/base properties of the water. Note observations in your table. Note
the “vigor” of the reaction to make a comparison of reactivity to other reactions.
Demonstration #2: Combustion of Phosphorus
Watch the teacher at the fume hood, you will repeat this reaction for sulfur. Test for
acid/base properties of the water. Note observations in your table. Note the “vigor” of
the reaction to make a comparison of reactivity to other reactions.
Test #3: Combustion of Magnesium
REMEMBER NOT TO LOOK DIRECTLY AT BURNING MAGNESIUM – IT IS
VERY BRIGHT!! Hold a piece of magnesium in a tongs and light it with a match (or
burner if the match doesn’t work). Collect ash in a small beaker or watch glass. Mix the
ash with water and test for acid/base properties. Note observations in your table. Note
the “vigor” of the reaction to make a comparison of reactivity to other reactions.
Demonstrations #4: Combustion of Calcium
Pay attention to the “vigor” of the reaction to make a comparison of reactivity. Note
whether the ash mixed with water is acid or base.
Test #1: Reaction of Sodium and water
SAFETY – WEAR GOGGLES & BE SURE TO GET THE SHIELDING GLASS
OVER THE BEAKER IMMEDIATELY. Hot sodium can easily splatter. It will burn
through skin quickly. Eyes would be worse. Use caution and stay calm!
Take a forceps (tweezers) to a small Petri dish labeled “Na” for “Sodium”. Take ONE
small piece of sodium to your desk and examine it on a DRY GLASS PLATE. Note the
softness (use only the forceps to touch it), and color. Add 1 cm of water to a beaker, one
small enough that this glass plate will cover completely. Invert the glass plate over the
beaker so the sodium chunk falls into the water. Tap the glass a little for encouragement
if needed. Pay attention to the “vigor” of the reaction to make a comparison of
reactivity. Test the acid/base properties of the products in a water solution.
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GROUP/PERIODIC PROPERTIES LAB
Test #2: Reaction of Potassium and water
SAFETY – WEAR GOGGLES & BE SURE TO GET THE SHIELDING GLASS
OVER THE BEAKER IMMEDIATELY. Hot potassium can easily splatter. It will
burn through skin quickly. Eyes would be worse. Use caution and stay calm!
Take a forceps (tweezers) to a small Petri dish labeled “K” for “Potassium”. Take ONE
small piece of sodium to your desk and examine it on a DRY GLASS PLATE. Note the
softness (use only the forceps to touch it), and color. Add 1 cm of water to a beaker, one
small enough that this glass plate will cover completely. Invert the glass plate over the
beaker so the potassium chunk falls into the water. Tap the glass a little for
encouragement if needed. Pay attention to the “vigor” of the reaction to make a
comparison of reactivity. Test the acid/base properties of the products in a water
solution.
Test #3: Reaction of Calcium and water
Take a small piece of calcium and add it to ½ inch of water in a beaker. Pay attention to
the “vigor” of the reaction to make a comparison of reactivity. Test the acid/base
properties of the products in a water solution.
Test #4: Reaction of Magnesium and water
Take a small piece of calcium and add it to ½ inch of water in a beaker. Pay attention to
the “vigor” of the reaction to make a comparison of reactivity. Test the acid/base
properties of the products in a water solution. If you are unable to react magnesium and
water at room temperature, put the magnesium in a test tube with water and heat it to try
to react the magnesium. SAFETY: POINT ANY HEATED TEST TUBE AT THE
WALL, NOT AT PEOPLE!! Phlarping happens!!! and we don’t want hot liquids
flarped on people.
The bottom line: Hand in a lab report per two students
Table of observations: Make it clear and neat. Group elements in the same groups that
are on the periodic table.
Discussion: Based upon what was observed, answer and explain why 1- Do the elements in group I (left column of the periodic table) get more reactive
or less reactive as you go down in the group?
2- Do the elements in group II (2nd column of the periodic table) get more
reactive or less reactive as you go down in the group?
3 – What happens as you go from group I to group II in the same period (periods
are the rows in the periodic table)
3- Are the oxides of the metals you tested acidic or basic?
4- Are the oxides of nonmetals you tested acidic or basic?
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GROUP/PERIODIC PROPERTIES LAB
4 - Write a chemical equations for each of the reactions observed and
experienced.
Bonus: 1. Balance all your chemical equations and make sure they are all correct.
2. Explain your answers to discussion questions #1 and #2 using the concept of effective
nuclear charge. Recall there is a trend in effective nuclear charge. Compare it to the
reactivity and use that comparison to explain your observations.
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GROUP/PERIODIC PROPERTIES LAB
Activity title:
Group and periodic properties lab
Summary:
In chemistry lab, students will observe and perform experiments with the elements
sodium, potassium, calcium, magnesium, sulfur and phosphorus. Conclusions will be
made about trends down groups, across periods and relating to acidity/basicity of
metal oxides vs. nonmetal oxides
Goals:
- Introduce students to elemental chemicals and their reactions
- introduce trends in periodic table
- challenge students to identify products in a chemical reaction
Standards match
GRADE 9–12 II. PHYSICAL SCIENCE B. Chemical Reactions The student will describe
chemical reactions and the factors that influence them - 1. The student will describe chemical
reactions using words and symbolic equations This laboratory also addresses more advanced
chemical concepts of periodic properties and acid/base applications. It extends past the scope of
the Minnesota Academic Science Standards
Context –
this lab was designed for advanced high school chemistry students (juniors or
seniors) who can be trusted with small amounts of potentially hazardous chemicals.
It can be used at any time when discussion of elements in the periodic table is
desired. It’s original design was later in the year as a fun introduction to a
theoretical discussion of periodic properties after chemical reactions and chemical
equations have been discussed.
Activity description:
The elements sodium, potassium, calcium, magnesium, sulfur and phosphorus are
reacted with water or oxygen in the air as appropriate by students and/or as a
demonstration. Safety measures are taken to ensure proper use of the chemicals.
Students are asked to make observations about reactivity and use these observations
to derive group and periodic trends in reactivity. See attached lab handout for full
details and teaching notes for setup and management notes.
Teaching notes:
- fume hood is needed for combustion of sulfur and phosphorus. They both make a
mess, so keep reusing the same spoon and plan on spending your lunch hour with
the confligurating spoon in a Bunsen burner flame to remove excess gunk.
- Chop the potassium and sodium in tiny chunks less than a small pea
- Emphasize using a glass cover on the beaker immediately upon adding the
potassium and sodium. Demonstrate this. Do not leave extra potassium or
sodium around for the curious student to test too often.
- Usually the mineral oil used to store potassium and sodium creates a bunch of
smoke. Alert students that this is not part of the reaction.
- Pound the calcium into a super thin strip to mimic the magnesium strip. Be
prepared for flying chunks of calcium when you ignite it. It’s far more violent
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GROUP/PERIODIC PROPERTIES LAB
-
than magnesium, but hard to get it thin enough to burn. A hammer on the black
lab bench works well and keeps neighboring classes entertained.
Reemphasize to look away from the magnesium
Demonstrate anything that you feel is not appropriate for your students to do.
Find the u-tube video of Brainic’s “alkali metals” to tie into this lab as a follow
up when discussing it.
Expect that writing chemical equations for all reactions will create some
difficulty. Note that for metals reacting with water that hydrogen gas and
hydroxides are products.
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GROUP/PERIODIC PROPERTIES LAB
Assessment: A student lab report is collected. Included is a table showing
observations, proposed chemical equations for reactions, and proposed periodic and
group trends in reactivity. The report is intended to be graded for thinking, not
perfection in the chemical equations as some of these reactions are difficult to
characterize.
Short description:
Students will observe and perform experiments with the elements sodium, potassium,
calcium, magnesium, sulfur and phosphorus. Conclusions will be made about trends
down groups, across periods and relating to acidity/basicity of metal oxides vs.
nonmetal oxides
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