Atoms and Molecules
- History of the Atom
- Models for the Atom
- Subatomic Particles
- Periodic Table
- Periodic Trends
- Polyatomic Ions
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|Reactions - Physical and Chemical Changes|
Study the primary definition of this concept, broken into general, basic, and advanced English definitions. Also see the mathematical definition and any requisite background information, such as conditions or previous definitions.
The substances are not altered chemically, but merely changed to another phase (i.e. gas, liquid, solid), separated, or combined.
Real World Application
Discover processes or disciplines in the natural or man-made worlds that employ the concept.
Boiling water for a cup of noodles is a physical change that involves changing phase.
Tearing a piece of paper is a physical change that involves changing shape.
Pouring your liquid cake mix into different shapes using baking molds is a physical change with shape.
Making a snow man is a physical change for shape.
Turning a large chunk of iron into iron wire or nails is a physical change that may involve both phase change (melting the iron) and shape (molding or extruding the iron).
Learn important vocabulary for this concept, including words that might appear in assessments (tests, quizzes, homework, etc.) that indicate the use of this concept.
Browse relevant videos from the Journal of Chemical Education's (JCE) Chemistry Comes Alive! library and other video sources.
Boiling water is only a phase change. Therefore, it is a physical change.
Making a snow man does not involve any chemical change. (Ok, maybe not the part where the snow man comes to life.) It only involves putting stuff together without reaction with each other.
Experience computer simulators or animations that illustrate the concept discussed here. Many simulators or animations come with worksheets for use in class.
Investigate lab procedures suitable for live classroom demonstrations or guided student exploration.
Students requiring adaptations to gain the full benefit of a demonstration may find a worksheet with guided observations useful. Alternatively, a teacher may wish to use a worksheet with guided observations to model what observations all students should be making during a demonstration.
The Demonstration Observation Worksheet is available in
Read a summary of the concept, indicating the enduring understanding students should retain after class.
There is a physical change if there is no new substance generated after the change. Ice and water are made of exactly the same the same substance, only the state is different. Physical changes also include energy exchanges or separation/combinations.