1. Elements, Compounds, & Formulas Textbook Sections 14.5

2. Elements  (def. ) Matter in its purest form  Made up of the same atoms

3. Compounds  (def.) A substance made up of 2 or more different elements  Chemically bonded H2OH2O

4. Properties of Compounds  Very different from the elements they are made of  Elements are chemically bonded which affects how they behave together

5. Element or Compound? N2N2 A: Element B: Compound Liquid Nitrogen

6. Element or Compound? C 6 H 12 O 6 A: Element B: Compound Glucose

7. Element or Compound? H2O2H2O2 A: Element B: Compound Hydrogen Peroxide

8. How To “Read” Chemical Formulas In Chemistry Elements = “Letters” & Compounds = “Words” 1. The letters tell you the element. 2. The subscripts (small numbers) tell you how many atoms of that element to the left are in the molecule - If there is no number = 1 atom 3. If there are parentheses around part of the compound, you must multiply everything inside by the subscript to the right of it C 2 H 6 O

9. “Reading” Practice A: 1 hydrogen, 2 oxygen B: 2 hydrogen, 2 oxygen C: 2 hydrogen, 1 oxygen D: None of the above H2OH2O

10. “Reading” Practice NaCl A: 1 sodium, 1 chlorine B: 0 sodium, 0 chlorines C: Not enough information D: None of the above

11. “Reading” Practice K2C2O4K2C2O4 A: 1 potassium, 2 carbons, 2 oxygen B: 2 potassium, 2 carbons, 4 oxygen C: 8 potassium, 8 carbons, 4 oxygen D: None of the above

12. “Reading” Practice Zr 3 (PO 4 ) 4 A: 1 zirconium, 3 phosphorus, 16 oxygen B: 3 zirconium, 1phosphorus, 8 oxygen C: 3 zirconium, 4 phosphorus, 8 oxygen D: 3 zirconium, 4 phosphorus, 16 oxygen

13. Elemental Formula O2O2 1. If the basic unit = 1 atom: Atomic Symbol 2. If basic unit = More than 1 atom: Atomic Symbol #

14. Elemental Formula Practice Ex 1: The basic unit for hydrogen is made up of 2 atoms. What is its elemental formula? A: 2HB: H 2 C: H 2 D: HH

15. Elemental Formula Practice A: 1AuB: Au 1 C: Au Ex 2: The basic unit for gold is made up of 1 atom. What is its elemental formula? D: Au 1

16. Elemental Formula Practice Ex 3: The basic unit for sulfur is made up of 8 atoms. What is its elemental formula? A: S 8 B: 8S C: SSSSSSSS D: S 8

17. In-Class Practice Take out a piece of paper. Write the questions AND your answers PART ONE: With Your Partner, identify: Whether the substance is a COMPOUND or ELEMENT How many atoms of each ELEMENT is in the substance (write the element name!) READY?

18. In-Class Practice 1. Ba 2 V 2 O 7 2. C 5 H 10 N 2 O 3 3. Fe(OH) 3 4. (C 6 H 5 ) 4 Ge 5. Hg 3 (AsO 4 ) 2

19. In-Class Practice PART TWO: With Your Partner, identify: Figure out the elemental formulas for the molecules described READY?

20. In-Class Practice 1. Chlorine can form a molecule by bonding 5 of its atoms together 2. The basic unit for sulfur is made from 2 sulfur atoms 3. Carbon can form a molecule made up of 20 of its atoms 4. What is the elemental formula if fluorine was able to create a molecule by bonding 3 of itself together?