Activity—Modeling Matter
Physical Science
MTHS/Marsden
Name _____________________________
READ: Today we are going to “model” elements, compounds and mixtures. A model is representation of an object or event that makes it easier to understand things that are too difficult to directly observe with our senses. A map is a model of a city. A globe is a model of the earth. A cell diagram is a model of a cell.
We cannot directly see the parts or composition of elements, compounds and mixtures so we will be modeling them with Legos.
(1) Based upon the reading above, why is it useful to model cities, the earth and cells rather than just
“observing” them?
Directions: Working in pairs at your desks use the bag of Legos © in order to model each of the following materials and answer the following questions in your notebook. Be sure to draw your Lego models.
(2) Since the Legos are a representation of matter, what would one single Lego best represent?
(3) Observe the container of Legos. Does the container of all of the Legos best represent a model of a pure or impure substance? Explain.
(4) Separate your container of Legos into 3 different piles of elements. Explain why you classified the
Legos into the groups that you did.
READ: Legos are obviously just a model or stand-ins for elements, compounds and mixtures. Elements are defined as “a substance that cannot be broken down into simpler substances” (p. 39), while compounds are defined as “substances composed of two or more simpler substances joined together chemically and can be broken down into those simpler substances by chemical methods but not through simple separation methods”.
(6) In your lab group, have each person “model” a different compound with your Legos. How is a compound different from an element? How is a compound similar to an element (HINT: Look at question # 1)?
(7) How is a model of a compound different from a mixture? How is a model of a compound similar to a mixture? Check your answers to # 6 & 7 for a stamp.
(A)
(8) Which of the following “models” represents a “pure” substance vs. “mixture”? Explain how you classified your matter.
(B) (C) (D)
(9) Classify each of the previous “models” (A-D in # 8) as representations of elements, compounds or mixtures. Explain how you classified each.

Activity—Modeling Matter Name _____________________________
READ: Substances can be classified as either pure or mixtures. The two types of substances that can be classified as “pure” are BOTH elements and compounds. Elements consist of one type of atom (although a sample of a substance will naturally contain more than one single atom) and compounds consist of more than one type of atom chemically joined or bonded together. Symbolically, Elements are represented with either one single CAPITAL letter (like S, P, B, C or N) or one capital letter followed by one non-capitalized letter (like Na,
Si, Mg, Br). This means that a compound is represented with two or more elements written next to each other
(like LiF or BCl
3
). Note that the numbers (like the 3 in BCl
3
) mean that there are 3 of that type of element in the compound. This means that BCl
3
contains one Boron atom and three chlorine atoms. If no chemical formula is shown, the substance is likely a mixture.
(10) The following are descriptions of several elements, compounds and mixtures. Classify them as either Pure
(P) or Mixtures (M).
Tap water ______
Sugar (C
6
H
12
O
6)
_______
Table Salt (NaCl) _______
Air ________
Salt water ______
Coke ______
Ranch Dressing_______
Oxygen (O
2
) ________
CO
2
_______ water (H
2
O)______ blood ______
Hydrogen (H
2
)______
Hydrogen peroxide (H
2
O
2
) _______ Aquafresh toothpaste ______
(11) Which of the “Pure” substances above are elements? Which are compounds? Explain how you know.
(12) Which of the “Mixtures” above are homogenous? Which are heterogeneous? Explain how you know.
READ: Mixtures are not always so easy to identify. For example, you probably identified salt water as a mixture because you know that it has both salt and water (duh) in it. You probably said the same thing about
Aquafresh toothpaste because it has those nice red, white and blue strips (mmmmm…aquafresh). But what if I handed you a container of really nicely mixed salt water so that it looked just like pure water and asked you to tell me whether it was a mixture or a compound?
(13) If you were given a clear liquid, what could you do experimentally to the liquid in order to determine whether it was pure or a homogenous mixture? (see page 50 for help) Check your answer with Ms. Marsden
(14) Classify each of the following as either a compound, a homogenous mixture or a heterogeneous mixture.
Distilled water _____ Sewer water _____ Garden hose water _____
Water in the nature-scape ____ River water _____ Ocean water ____
(15) Classify each of the following as either a compound, a homogeneous mixture or a heterogeneous mixture.
(You can ask me if you’re unsure about composition).
A stream with gravel at the bottom _____ Salt water _____ Propane (C
3
H
8
) _____
Coke _____ Chocolate Chip Cookies _____ Baking Soda (NaHCO
3
) ______