2. Key concepts/skills: Level 1: Define key vocabulary. Level 2: Classify substances given their symbols or formulas. Level 3: Compare and contrast elements and compounds.

3. Key vocabulary: Pure substances compound molecule Elements formula Element symbol atom (review)

4. Pure Substances – made up of only one type of atom or molecule (Au) (H 2 0 a glass of water is made of only H 2 0 moecules) I.Elements – matter that cannot be broken down into a more simple form A.Each of the 118 elements is represented by a symbol B.The symbol is always capital/ the second letter of a symbol is always lower case

5. A.Symbols are named after people and places and do not always match the word B.Calcium – Ca, Potassium – K, Carbon - C

6. II. Compounds – more than one type of atom joined chemically A.Formulas are symbols and subscripts that tell what kind of atom and how many of each atom is in the Compound B. Ammonia – NH 4, Carbon dioxide – CO 2, Glucose sugar – C 6 H 12 O 6

7. Elements Symbols K- Potassium Cu - Copper Compounds Formulas CO2 –carbon dioxide NH 3 - Ammonia

8. Examples of Elements and Symbols

9. Examples of Compounds and Formulas

10. Element or Compound?