Lesson 7: Classifying Matter
In this lesson, you have been introduced to the idea of mixtures and compounds. Keep in mind that compounds are made up of elements in fixed proportions and mixtures do not have fixed proportions. Also, compounds are chemically combined, but mixtures are not. This lesson served as a basic introduction to chemistry. In future units, you will look more closely at chemistry, and the new understandings that you are developing should expand further. Keep in mind that the world around you is made up of different compounds and that the complexity around you is the result of things that you cannot see with the naked eye.
Questions to Discuss
- What is the difference between a mixture and a compound? (A compound is a chemical combination of elements in fixed proportions. Mixtures are the result of elements or compounds that are not chemically combined but are mixed together in a various proportions that do not have to be fixed.)
- What is the difference between a compound and an element? (Compounds are combinations of elements in fixed proportions. Elements are the purest forms of matter that do not exist in combination with other elements.)
- Can compounds be changed into new compounds? (Yes, compounds can be changed as a result of stimuli that can cause a chemical reaction.)
Things to Review
- Compounds are substances formed by the chemical combination of elements in fixed proportions.
- Compounds can be separated into simpler substances by chemical reactions.
- Fixed proportions are unchanging quantities of elements that are part of a compound.
- Mixtures are a combination of two or more substances that are not chemically combined.