Unit 04 · States of Matter & Gas Laws
Matter behaves the way it does because of how its particles move and attract one another. This unit covers kinetic molecular theory, the gas laws that relate pressure, volume, temperature, and amount, the energy bookkeeping of phase changes, and the intermolecular forces that set boiling points and explain why some substances are gases and others solids at room temperature. Mastery means you can connect particle-level motion to a measurement on a gauge.
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| Kinetic molecular theory | Describes gases without reference to particle motion. | States the postulates but cannot apply them to behavior. | Uses KMT to explain pressure, temperature, and why real gases deviate from ideal. |
| Gas laws & the ideal gas equation | Plugs numbers into the wrong law or wrong units. | Uses single-variable laws but fumbles PV = nRT. | Selects and applies the correct gas law, tracking units and absolute temperature throughout. |
| Phase changes & energy | Thinks temperature always rises as heat is added. | Names the phase changes but ignores latent heat plateaus. | Reads a heating curve, accounts for latent heat, and explains constant T during a transition. |
| Intermolecular forces | Confuses intermolecular forces with chemical bonds. | Lists the force types but ranks their strength inconsistently. | Identifies dominant forces and uses them to predict boiling point, viscosity, and volatility. |
| Lab technique (gas / pressure measurement) | Misreads the gauge or loses gas to leaks. | Collects data but mishandles temperature or pressure correction. | Measures gas behavior accurately and verifies a gas law against collected data. |
| Integration (cross-domain) | Treats the science as isolated facts; makes no cross-domain connection. | Names a link to history, reading, or writing but cannot defend why it matters. | Connects the unit to its anchor across History · Reading · Writing (plus chosen electives) and defends why the connection matters. |
“When I heated the sealed syringe the pressure climbed, because the molecules hit the walls harder and more often. And water boils at a lower temperature up a mountain because there’s less air pressure for the vapor to push against.”
“Gas just spreads out when it’s hot. The gas law is PV equals something. Boiling is always 100 degrees.”
You demonstrate this unit through a gas-collection or pressure–volume lab and a heating-curve investigation, explaining the particle behavior behind every measurement aloud — not a multiple-choice test. A criterion counts as mastered only when your data confirms the law and you can justify the molecular cause. Mastery is demonstrated, not awarded.
A 5-page clipboard packet — unit overview, key terms, the mastery rubric, anchor examples, and a score sheet you can print and grade against.