1. Elements, Mixtures, and Compounds

2. Review… Element: What is the smallest unit of an element?

3. Compound A substance made from 2 or more elements that are joined chemically. The properties of a compound are different from the properties of the elements making up the compound. Example: Sodium (VERY reactive metal) and Chlorine (poisonous green gas) combine to form ??? The smallest unit of a compound is a molecule.

4. Mixture Formed when materials are mixed together, but are not chemically bonded. You can physically separate the components. The properties of the components do not change. Examples: salt water, air, blood

5. Compound or Mixture? Water? Cake Batter? Sugar? Kool-aid?

6. Chemical Formula Shorthand way of showing the kinds and proportions of the atoms in a compound Examples: – C 6 H 12 O 6 –H2O–H2O – NaCl – 6CO 2 – 3H 2 O – 4NaCl

7. Chemical Formula The big number in front tells us the number of molecules of that compound. If no number is there, we assume the number is one. This is called the coefficient.

8. Chemical Formula The subscripted numbers (dropped down) tell us how many individual atoms of each element there are in one molecule of the compound. If no subscript is there, assume the number is one.