1. Chemical Reactions
Combining elements

2. The Law of Conservation of Mass
The Law of Conservation of Mass states that the amount of matter in the universe is constant
This means that you can’t really ever destroy or create anything, you just change it from one form to another!

3. Chemical formulas Na + Cl  NaCl
Chemical reactions have 2 parts, the reactants and the products
Think of the reactants as the “ingredients” of the reaction – what goes in.
The products are what comes out.
Na + Cl  NaCl
Sodium and chlorine are the reactants
… and salt is the product.
Products
Reactants

4. Numbers and letters
The letters are the chemical symbols – N for nitrogen, C for carbon, etc. They always start with a CAPITAL letter.
If there is a capital next to another capital, it is two different elements.
NaOH is sodium, oxygen and hydrogen
KCl is Potassium and chlorine

5. The little numbers after the symbols are called subscripts, that’s how many of each type of atom is in a compound.
NaCl has 1 sodium and 1 chlorine atom
H2O has 2 hydrogen atoms and 1 oxygen atom
C6H12O6 has 6 carbon, 12 hydrogen, and 6 oxygen atoms

6. If there are parentheses, you multiply the number outside by the number inside to find the total – Al2(SO4)3 has 3 sulfur and 12 oxygen atoms
Coefficient – the large number in front, it means that is the number of molecules. If there is no number, assume it is 1.
6HNO3 means that there are 6 hydrogen, 6 nitrogen, and 18 oxygen atoms in this molecule

7. Review How many of each type of atom are in: HNO3 C6H18 3CCl4 2MgCl2
Cu(NO3)2

8. Chemical Formulas and the Law of Conservation of Matter
In a formula, the number of atoms stays the same.
If you have 20 atoms in the reactants, there must be 20 in the products.
Does this equation follow the law of conservation of mass?
H2 + O2  H2O
No, because there are 2 O atoms on the left and only one on the right.
What about now…?
2H2 + O2  2H2O
Yes, now there are equal numbers of atoms on both sides

9. Are these balanced? Al + Cl2  AlCl3
No, there are too many chlorine atoms in the reactants.
2HCl + Na2S  H2S +2NaCl
It is already balanced!
NaCl + CaSO4 Na2SO4 + CaCl2
No, the chlorine and sodium atoms are not balanced.
KOH + HCl  KCl + H2O

10. Energy
Chemical reactions always either release or absorb energy (heat)
When they absorb energy, it is known as an endothermic reaction
When they release heat it is called an exothermic reaction
Photosynthesis (when plants make sugar using carbon dioxide and water) is endothermic – it absorbs energy from the sun.
A campfire burning is exothermic – it releases energy from the wood.

11. Types of Reactions
Synthesis – a complex molecule is created from simple molecules
2H2 + O2  2H2O
Decomposition – Simple molecules are created from a complex molecule
H2CO3 H2O +CO2
Single replacement – An element takes the place of another element
Zn + 2HCl  ZnCl2 + H2
Double replacement – ions in different compounds switch places
NaCl + AgNO3  NaNO3 + AgCl

12. Compounds
Compound - a pure substance composed of two or more elements chemically combined
Molecule – smallest piece of a compound – made of atoms chemically bonded together.
Hydrogen
Carbon
Oxygen
Molecule
Compound

13. Types of Compounds
Ionic
Covalent
Acids
Bases
Salts
Organic Compounds

14. Acids pH < 7
Substance that releases hydrogen ions when dissolved in water
Taste sour
Conduct electricity
Turn blue litmus paper red
Turn cabbage juice red
HCl – Hydrochloric Acid – in the stomach for digestion
H2SO4 – Sulfuric Acid – in batteries

15. Bases pH > 7 Substance that releases OH- ions in water Taste Bitter
Conduct electricity
Turn red litmus paper blue
Turn cabbage juice blue
Feel slippery
NaOH – Sodium Hydroxide (lye) - in cleaners
NH3 – Ammonia

16. Salts
Substance formed from positive ion of a base and the negative ion of an acid
When an acid and a base are combined, they produce a salt and water
HCl + NaOH  NaCl + H2O
Acid Base Salt Water
This is known as neutralization

17. c Organic Chemistry The Chemistry of Carbon
More than 90% of known compounds are organic.
Because carbon has 4 valence electrons, each atom can form 4 bonds.
Carbon can combine in many ways with itself and other elements to form all living things. c

18. The Big Six CHNOPS elements found in living things: Carbon Hydrogen
Nitrogen
Oxygen
Phosphorous
Sulfur
CHNOPS

19. Biochemicals organic compounds made by living things Carbohydrates
There are four types
Carbohydrates
1 or more simple sugars bonded together; used as a source of energy
Sugars and starches
Energy and energy storage
Glucose – C6H12O6

20. 2. Lipids 3. Proteins Do not dissolve in water Fats, oils and waxes
Store energy, make up cell membranes,
moisture for skin
3. Proteins
Structure, store materials, transport,
regulate chemical reactions
Enzymes, antibodies
Built of amino acids
Lipid!
Protein!

21. 4. Nucleic Acids – DNA and RNA
Blueprint for life
Tell your body what proteins are needed to make… you! ..and every other living thing
In the nucleus of every cell of every living thing on Earth.

22. Polymers Organic compounds in long chains Useful!
Low melting point, flexible, easily molded
A little variation and they can be made harder, softer, tougher, weaker, etc.
Rubber, polyethylene (in plastic bags, etc.), nylon, PVC,