Grade 8 Unit 02 Review: Chemical Formulas and Reactions

1. 1. Use the table above to answer the questions.
   1. a. How many hydrogen atoms are in ammonia?
   2. b. How many hydrogen atoms are in acetone?
   3. c. How many hydrogen atoms are in ammonium sulfate?
   4. d. How many elements are in acetone?
2. 2. What are diatomic elements? Which elements are diatomic? How many atoms are in a diatomic molecule?
3. 3. What is the difference between physical and chemical changes?  What are some signs that a chemical reaction is happening?
4. 4. In a chemical formula, what are the cooefficient and subscripts?  What do they mean?
5. 5. What is a precipitate?
6. 6. What is the law of conservation of mass?  How does it apply to chemical reactions?