An active, hands-on science station lab where middle or early high school students rotate through eight everyday substance stations to investigate, classify, and defend whether samples represent atoms, molecules, compounds, or mixtures using particle-level evidence.
3. Golden Rule of Chemistry: A student claims: "All compounds are molecules, and all molecules are compounds." Is this student correct? Defend or refute their claim using at least two specific station examples.
Submit your completed investigation sheet to your teacher for review. Page 2 of 2
Continue to Page 2 for Stations 5–8, Synthesis Key, and Grading Rubric Teacher Guide • Page 1 of 2
II
Particle Patrol • Key (Stations 5–8) & Rubric
Teacher Master Key
Station 5: Copper Wire (Cu) ATOM / ELEMENT
Evidence: Made purely of copper atoms (#29) in a metallic crystal lattice. No other elements are present, and it cannot be separated into simpler substances.
Station 6: Carbon Dioxide (CO₂) MOLECULE & COMPOUND
Evidence: Molecule because 3 atoms are bonded into a discrete unit (O=C=O). Compound because it contains 2 different elements (C and O) in a fixed 1:2 ratio.
Station 7: Salad Dressing MIXTURE (Heterogeneous)
Evidence: Physical blend of oil, vinegar, and seasoning particles. They can be physically separated (filtration/settling) and retain separate visible phases.
Station 8: Oxygen Gas (O₂) MOLECULE (Element)
Evidence: Molecule because 2 atoms are chemically bonded. NOT a compound because both atoms are the same element (Oxygen). Crucial teaching checkpoint!
Synthesis Challenge • Model Answers
Q1. Why is H₂O a compound while O₂ is not?
A compound must contain two or more different chemical elements bonded together. Water has hydrogen AND oxygen (2 different elements). Oxygen gas (O₂) has two bonded atoms, but they are both the same element, making it a diatomic elemental molecule, not a compound.
Q2. Mixtures: Air (Homogeneous) vs. Salad Dressing (Heterogeneous):
Both are mixtures because their components are physically combined without chemical bonding. Air is homogeneous because the gas molecules are evenly distributed at the molecular level with uniform appearance. Salad dressing is heterogeneous because oil and vinegar do not dissolve in each other, resulting in visible layers and distinct spice particles.
Q3. "All compounds are molecules, all molecules are compounds" - Refutation:
The student is incorrect. First, not all molecules are compounds: O₂ is a molecule but not a compound because it only has one element. Second, not all compounds exist as discrete molecules: NaCl (table salt) forms an extended ionic crystalline lattice rather than isolated independent molecules.
Standards-Based Assessment Rubric (NGSS MS-PS1-1)
Criterion
4 • Exemplary
3 • Proficient
2 • Developing
1 • Beginning
Classification Accuracy (Stations 1–8)
7–8 stations correctly classified, including dual classifications (H₂O, CO₂).
Partner Check: [ ] Target Met [ ] Rule Met Score: ___ / 4 pts
Boss Challenge • The Double-Roll Metamorphosis
Bonus 5 Pts
Mission: Choose one of your models from above. In Box A, sketch what happens if you apply a physical change (e.g. state change or mixing). In Box B, sketch what happens if a chemical change occurs (chemical bonds break and form new substances).
Box A: Physical Change (Same bonds, new state/blend)
Box B: Chemical Change (New bonds & substances)
Official Game Tally: Rounds 1–4 (16 pts max) + Boss Challenge (5 pts max)
Grand Total:
/ 21
Atomic Roll • Particle Modeling Game Sheet Page 2 of 2
