Angela's Tools · Chapter 2 · Molecules and Extended Structures
Worksheet 8 of 10
Twelve Substances, Four Columns: A Molecule and Structure Jigsaw
Learning target: I can teach a classmate the composition and structure of a substance from its card, work with a group to sort twelve substances into molecules, crystals and polymers, and explain which pairs of cards share something and what that teaches.
Collaborative investigationAbout 50 minJigsaw
MS-PS1-1 · practice
collaborationdiscussionvisual modeling
NameDatePeriod
Directions
Work in home groups of four. Step 1 (expert round, 10 minutes): each member takes one expert set of three cards (Set A: cards 1-3; Set B: cards 4-6; Set C: cards 7-9; Set D: cards 10-12), reads them, and meets briefly with the other students who hold the same set to agree on the category and the composition of each card. Step 2 (home round, 20 minutes): return to your home group, teach your cards to the others, and complete the group task. Step 3 (defense, 10 minutes): present your sorting and your four teaching pairs to a neighboring group, who will challenge one placement. Step 4 (individual, 10 minutes): answer Part C alone.
You will need: This worksheet, One set of twelve cards per home group (cut from the sheet or printed separately), Pencil
Twelve substance cards
1 Card 1: Water, H₂OTwo hydrogen atoms each bonded to one oxygen atom; 3 atoms in a particle with an edge. A liquid at room temperature; you drink it.
2 Card 2: Hydrogen peroxide, H₂O₂Two oxygen atoms bonded to each other, with one hydrogen on each oxygen (H-O-O-H); 4 atoms in a particle with an edge. A liquid used as a disinfectant and bleach; never drunk.
3 Card 3: Oxygen gas, O₂Two oxygen atoms bonded together; 2 atoms, one element only, in a particle with an edge. The gas your lungs take from the air.
4 Card 4: Ammonia, NH₃One nitrogen atom with three hydrogen atoms attached; 4 atoms in a particle with an edge. A sharp-smelling gas used in some cleaners and fertilizers.
5 Card 5: Butane, C₄H₁₀Four carbon atoms joined in a row, carrying ten hydrogen atoms; 14 atoms in a particle with an edge. A fuel in some camp stoves and lighters.
6 Card 6: Isobutane, C₄H₁₀The same 4 carbon and 10 hydrogen atoms as butane, but one carbon is joined to the other three, which are not joined to each other; 14 atoms. Used as a refrigerant and a spray-can propellant.
7 Card 7: Sodium chloride (table salt)Sodium and chlorine alternate in a repeating pattern in all three directions; 1 sodium for every 1 chlorine; no particle with an edge. Grains tend to be tiny cubes.
8 Card 8: Quartz, SiO₂Each silicon atom is bonded to 4 oxygen atoms and each oxygen is shared by 2 silicons, repeating in all directions; 1 silicon for every 2 oxygen; no fixed size. The main mineral in most sand.
9 Card 9: Diamond, CCarbon atoms only; every atom bonded to 4 neighbors in a rigid network that runs in all directions; no fixed size. The hardest natural material; tips cutting tools.
10 Card 10: Graphite, CCarbon atoms only; every atom bonded to 3 neighbors in flat sheets of six-sided rings; sheets held together only by weak attractions; no fixed size. Soft and slippery; the pencil core.
11 Card 11: Ice, H₂OWater molecules, still H₂O, locked into a regular repeating pattern in all three directions with six-sided symmetry; a crystal of any size. Snow crystals tend to show six-sided shapes.
12 Card 12: PolyethyleneOne carbon carrying two hydrogens, bonded to the next carbon, repeated in a chain thousands of units long; 1 carbon for every 2 hydrogen; no fixed length. Plastic bags and many bottles.
Part A: Expert round (one set per person)
1.Your expert set: ______. Complete the table for your three cards. Agree with the other experts on your set before you return to your home group.
| Card number and name | Category: molecule, crystal of atoms, crystal of molecules, or polymer | Composition: exact count or ratio (write it) |
|---|
| First card | | |
| Second card | | |
| Third card | | |
Part B: Home group task
- Each expert teaches their three cards in one minute each: the category, the composition, and the one feature that decides the category.
- Lay all twelve cards on the desk and sort them into four columns: molecule, crystal of atoms, crystal of molecules, polymer. Every column must have at least one card. Record the sorting in the group table.
- Find the four teaching pairs. Each pair is two cards that share something important but differ in one way. Hint: one pair shares the kinds of atoms, one shares the exact composition, one shares a single element, and one shares the very same molecules.
- For each pair, write one sentence that states what the pair teaches about composition, structure or extended structures.
- Prepare a one-minute defense of this question from the committee: 'Water and salt are both made of two elements. Why are they in different columns?' Every member must be able to give the defense.
Group record (fill in)
| Column | Card numbers | How composition is written (count or ratio) | One feature every card in the column shares |
|---|
| Molecule | | | |
| Crystal of atoms | | | |
| Crystal of molecules | | | |
| Polymer | | | |
2.Group answer: List the four teaching pairs by card number. For each, write what the two cards share and what the pair teaches.
3.Group answer: Write the placement the neighboring group challenged, their argument, and how your group answered.
Part C: Individual accountability (complete alone)
4.Cards 1 and 11 are both H₂O, yet your group placed them in different columns. Explain why ice is an extended structure while liquid water is a collection of molecules, and what stays the same in both.
5.A thirteenth card arrives: 'Nitrogen gas, N₂: two nitrogen atoms bonded together; most of the air.' Which column does it go in, and which card is it most like? Explain.
6.Using two of the teaching pairs as evidence, explain the sentence: 'Composition and structure together decide what a substance is.' Name the cards you use.
7.A fourteenth card reads: 'Table sugar: sucrose molecules (12 C, 22 H, 11 O) stacked in a regular repeating pattern in a grain.' Which column does it go in, and which existing card is it most like? Explain your reasoning.
The two sorting questions
If the sorting stalls, ask each card two questions in order. First: does the card describe a particle with an edge and an exact count of atoms? If yes, it is a molecule; stop. If no, it is an extended structure, so ask the second question: is the repeating unit an atom, a whole molecule, or a chain link? Atoms repeating in all directions means crystal of atoms; molecules repeating in all directions means crystal of molecules; a unit repeating in a line means polymer. Only cards 7 through 12 need the second question.
Design the thirteenth and fourteenth cards
Write two new cards in the same style: one for carbon dioxide (CO₂: one carbon atom bonded to two oxygen atoms) and one for polyvinyl chloride (PVC: a chain in which every pair of carbons carries three hydrogens and one chlorine). For each, give the category, the composition as a count or a ratio, and an everyday use. Then write a fifteenth card for a substance you choose, look up its structure in a reliable reference, and explain which column it belongs in and which existing card it is most like.