Chapter 1 · The Chemical World
1.3The Scientific Method: How Chemists Think
10 min · two checks
Predict
Is a scientific theory just a hunch that has not been proved yet?
The idea
- Order observation, hypothesis, experiment, and revision.
- Contrast a law with a theory using a chemistry example.
Chemists do not start with a verdict. They notice something — a metal gains mass when it burns in air, a solution changes color, a gas is evolved — and propose a hypothesis that could be wrong. An experiment is then built so that a failed prediction would count against the idea. Results either tighten the hypothesis or send it back for revision. Publishing the method matters as much as publishing the claim, because someone else has to be able to repeat the measurement.
A law compresses a pattern: mass is conserved in a chemical change; pressure and volume of a trapped gas move in opposite directions at constant temperature. A theory explains a family of patterns with a model of what particles are doing. Atomic theory and the kinetic molecular theory survived because they keep making successful predictions, not because someone declared them final. “Just a theory” confuses everyday speech with this stronger meaning.
Keep these
- A hypothesis must be testable; an experiment should be able to challenge it.
- A law states a pattern. A theory explains many patterns.
- Good conclusions stay tied to the measurements, and they get revised when new measurements disagree.