Lab: What Is That Stuff? Classifying types of substances, Part 1

Chemists classify “stuff” based on what particles make up the “stuff”. In this activity you will learn how to classify “stuff” the way chemists do. Do not open the individual bags of beads.

1. Examine the bags of beads given to you. Write down at least 3 characteristics of the different things you see in the bags. Do not take more than 2 or 3 minutes on this.

2. Now try to categorize the bags into three or more groups based on the way the different beads are arranged. For each grouping describe the specific characteristic(s) that you used to place the samples in that particular group.

Group 1
Group 2
Group 3
Group 4 (if needed)
Group 5 (if needed)

3. Assume now that each individual bead is an “atom”, and the different colors represent different types of atoms.

For each group use the following terms and describe your groups based on what you think each term means. Do not look these definitions up—just rely on what you already know. If you do not know what a term means, make a guess as to what you think it means, and match the term to the appropriate groups. Try to match each group with at least 2 of the terms; some groups may have more than 2: atom, molecule, element, compound, mixture, solid, liquid, gas.

Group 1
Group 2
Group 3
Group 4 (if needed)
Group 5 (if needed)

4. Based on what you have done, write down what you think the definition for each word is:

Atom
Molecule
Element
Compound
Mixture
Solid
Liquid
Gas

Lab: What Is That Stuff? Classifying types of substances, Part 2

Background: In chemistry, the important theory we use to explain the world around us is the idea that all matter is made up of tiny, fundamental, subatomic particles called atoms. According to the theory, atoms can combine and bond to form bigger particles called molecules. These theoretical particles are too small to ever be seen by human eyes, but they help us to accurately explain observations we can make.

The science of CHEMISTRY is best understood in three ways:

1. The submicroscopic—atoms and molecules which we can’t see.

2. The macroscopic—that which we can directly observe, or see, with our eyes.

3. The symbolic—chemical formulas and equations we use to represent #1 and #2.

In this activity, you will attempt to relate these three aspects of chemistry!

Procedure: Obtain a large plastic bag which contains smaller bags labeled A-J. Do not open the smaller bags, but observe the contents. Recall the groupings that you used in Part I of the lab.

Answer the following questions.

Word Bank (each term or phrase is used once): Element, Mixture, Compound, Pure, Submicroscopic Particles, Atoms, Molecules

1. What do the beads represent?

subatomic particles

2. Individual beads that are not stuck to other beads represent what type of submicroscopic particle?

atom

3. Beads that are stuck to other beads in a group represent what type of submicroscopic particles?

molecule

4. When all of the beads or groupings of beads look the same, this represents a substance that is

pure

Which bags fall into this category:

A, B, D, F, G, H

5. When the beads or groupings of beads are not all the same, this represents a

mixture

Which bags fall into this category:

C, E, I, J

6. A pure macroscopic substance made up of all of the same colors of beads represents an

element

Which bags fall into this category:

H, D

7. A pure macroscopic substance made up of different colors of beads represents a

compound

Which bags fall into this category:

B, F, G, I

Now that you have answered the above questions, complete the chart on the following page.

Letter on Bag / Element, Compound or Mixture / atom, molecule or both / Sketch of Contents—Use insert drawing! / Formula (use cards)
A / E / A / / He(g)
B / C / M / / CO(g)
C / M / B / / N2(g) + He(g) + Rn(g)
D / E / M / / Cl2(g)
E / M / A / / Ar(g) + Ne(g)
F / C / M / / NaCl(s)
G / C / M / / (CNH3)n(s)
H / E / M / / Cn(s)
I / C / M / / H2O(l)
J / M / M / / C2H6(g) + CH4(g)
K
(make up your own)
L
(make up your own)

Lab: What Is That Stuff? Classifying types of substances, Part 3

Procedure: Obtain bottles 1 through 12. These contain the following substance (not in this order): sulfur, magnesium, lead, polyvinyl chloride, brass, iodine, marble, glycerine, salt water, carbon dioxide, ammonium sulfate and air. Use the clues below to try to determine which bottle contains which substance, and also decide whether that substance is an “element,” “compound” or “mixture.” [You may not be able to distinguish all twelve substances.] Then complete the table on the next page.

sulfur is made up of molecules comprised of eight sulfur atoms (S8) bonded into a ring structure

magnesium is a shiny, silvery low density metal made entirely of magnesium atoms. Look on the Periodic Table for its symbol.

lead is a dull, grey, very dense metal made entirely of lead atoms. Look on the Periodic Table for its symbol.

polyvinyl chlorideor PVC is made up of long chain molecules which have two carbon atoms, three hydrogen atoms, one chlorine atom, two carbon atoms, three hydrogen atoms, one chlorine atom, over and over again; it can be formed into thin filaments or flat sheets

brass is a gold-colored alloy of the copper and zinc, containing usually between 15 and 40% zinc by mass [an alloy is a mixture of two or more metallic elements]. Look on the Periodic Table for the two symbols.

iodine is a brownish grey brittle solid that sublimes into a purple gas when heated; try putting the vial that you think is iodine into some boiling water; also, iodine is diatomic—that is, its molecules are comprised of two iodine atoms bonded together. So what would its formula be?

marble is also known as calcium carbonate: CaCO3; it is comprised of crystals that contain calcium, carbon and oxygen atoms in a 1:1:3 ratio, respectively

glycerine is a very viscous (slow-flowing) liquid; it is made up of molecules each of which contain three carbon atoms, eight hydrogen atoms and three oxygen atoms bonded together (C3H8O3)

salt water, as the name implies, is simply salt (NaCl) dissolved in water (H2O)

carbon dioxide is a gas with molecules comprised of one carbon atom and two oxygen atoms bonded together. So what would its formula be?

ammonium sulfate (NH4)2SO4 is comprised of crystals that contain nitrogen, hydrogen, sulfur and oxygen in a 2:8:1:4 ratio, respectively.

air is comprised of about 78% nitrogen molecules (N2), 21% oxygen molecules (O2), and small amounts of argon atoms (Ar), water molecules (H2O), carbon dioxide (CO2), and a bunch of other stuff.

Bottle # / Name of Substance / Chemical Formula(s) / E, C or M? (Element, Compound or Mixture?) / A, M or B? (Made of Atoms, Molecules or Both) / Sketch of particles
1 / marble / CaCO3 / C / M /
2 / sulfur / S8 / E / M /
3/8 / air / N2, O2, H2O, Ar, CO2 / M / B /
4 / salt water / NaCl + H2O / M / M /
5 / PVC / (C2H3Cl)n / C / M /
6 / glycerine / C3H8O3 / C / M /
7 / magnesium / Mg / E / A /
8/3 / carbon dioxide / CO2 / C / M /
9 / lead / Pb / E / A /
10 / brass / Cu + Zn / M / A /
11 / ammonium sulfate / (NH4)2SO4 / C / M /
12 / iodine / I2 / E / M /