Chemical+and+Physical+Changes



Learning from another wiki! [|Take the quiz!] Do you know the difference between chemical and physical changes? [|Quiz #2] One more quiz to test your knowledge.

__** Indications of a Chemical reaction: **__ (These are just signs that there may have been a chemical reaction. All of these don't have to happen for a chemical reaction to have taken place.) A - atoms are rearranged to make different molecules. B - bubbles. (Bubbles may be a sign of a gas being produced (not like soap bubble!) C- combustibility; color change D - different temperature; different smell

[|Chem 4 Kids - chemical reactions] This site has some great explanations of chemical reactions

__**Indications of a Physical change:**__ (These are just signs that there may have been a physical change. All of these don't have to happen for a physical change to take place.) S - State of Matter changes S - Size and/or Shape changes S - Same molecules; the molecules don't change S - Solubility
 * REMEMBER... In a "change of state",** the molecules stay the same, they just move faster if they get more energy and move slower if they get less energy. **MOLECULES - it's all about the molecules!**

Mixtures are two or more substances that are mixed together but not chemically joined. A good example of a mixture is a salad. There are tomatoes, lettuce, cucumbers, and salad dressing all mixed together. No chemical reactions occur between the vegetables and the dressing. You can separate each of the vegetables from each other. The molecules did not change when the substances were combined.
 * Mixtures (physical change)**