1. Compounds & Chemical Bonding
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09

2. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Chemical Reactions
A process in which substances undergo chemical changes, forming new substances with different properties.
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09

3. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Molecule
A combination of two or more atoms.
(Can be same element - ex. O2)
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09

4. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Compound
A substance made of two or more different elements chemically combined.
(ex. NaCl)
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09

5. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Valence Electrons
The electrons that are farthest away from the nucleus of an atom and are involved in chemical reactions.
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09

6. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Chemical Formula
A combination of chemical symbols.
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09

7. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Subscript
A number in a chemical formula that tells the number of atoms in a molecule or the ratio of elements in a compound.
H2SO4
Subscript
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09

8. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Elements (Chemical Symbols) ~ alphabet letters
Molecules/Compounds (Chemical Formulas) ~ words
Chemical Reactions (Chemical Equations) ~ sentences
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09

9. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Water
Chemical Formula
= H2O
Elements?
= Hydrogen (H) & Oxygen (O)
Subscript / # of atoms?
= 2 H atoms bonded to 1 O atom
Total Atoms?
= 3
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09

10. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Carbon Dioxide
Chemical Formula
= CO2
Elements?
= Carbon (C) & Oxygen (O)
Subscript / # of atoms?
= 2 O atoms bonded to 1 C atom
Total Atoms?
= 3
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09

11. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Sugar
Chemical Formula
= C12H22O11
Elements?
= Carbon (C), Hydrogen (H) & Oxygen (O)
Subscript / # of atoms?
= 12 C atoms & 22 H atoms bonded to 11 O atoms
Total Atoms?
= 45
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09

12. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Now you do it!
List the elements in the compound
How many atoms of each element are in the formula?
How many total atoms are in one molecule?
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09

13. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Carbon Monoxide
Formula = CO
List the elements
# of atoms of each element
Total # of atoms
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09

14. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Carbon Monoxide
Formula = CO
List the elements = Carbon (C) & Oxygen (O)
# of atoms of each element
= 1 C atom and 1 O atom
2)Total # of atoms
= 2
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09

15. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Propane
Formula = C3H8
List the elements
# of atoms of each element
Total # of atoms
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09

16. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Propane
Formula = C3H8
List the elements = Carbon (C) & Hydrogen (H)
# of atoms of each element
= 3 C atoms bonded to 8 H atoms
Total # of atoms
= 11
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09 16

17. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Rubbing Alcohol
Formula = C3H8O
List the elements
# of atoms of each element
Total # of atoms
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09

18. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Ammonia
Formula = NH3
List the elements
# of atoms of each element
Total # of atoms
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09

19. Sodium Chloride (Salt)
Formula = NaCl
List the elements
# of atoms of each element
Total # of atoms
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09

20. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Baking Soda
Formula = NaHCO3
List the elements
# of atoms of each element
Total # of atoms
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09

21. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Rubbing Alcohol
Formula = C3H8O
List the elements = Carbon (C), Hydrogen (H), & Oxygen (O)
# of atoms of each element
= 3 C atoms & 8 H atoms bonded to 1 O atom
2) Total # of atoms
= 12
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09 21

22. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Ammonia
Formula = NH3
List the elements = Nitrogen (N) & Hydrogen (H)
# of atoms of each element
= 1 N atom bonded to 3 H atoms
Total # of atoms
= 4
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09 22

23. Sodium Chloride (Salt)
Formula = NaCl
List the elements = Sodium (Na) & Chlorine (Cl)
# of atoms of each element
= 1 Na atom bonded to 1 Cl atom
Total # of atoms
= 2
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09 23

24. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Baking Soda
Formula = NaHCO3
List the elements = Sodium (Na), Hydrogen (H), Carbon (C), & Oxygen (O)
# of atoms of each element
= 1 Na atom, 1 H atom, & 1 C atom bonded to 3 O atoms
Total # of atoms
= 6
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09 24

25. Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09
Chemical Bonding
Chemical bonds form between atoms when valence electrons move between them.
Electrons may be transferred from one atom to another, or they may be shared between the atoms.
Unit 4 (Ch. 9) – Reactions/Chem. Living Systems Bach 11/03/09