1. Chemical Reactions Unit 8 Part 1

2. Unit 7 Exam Analysis  Averages  Chemical Naming+/25  Chemical Bonding+/15  Periodic Table Trends+/10

3. Term 1 Update…Finish STRONG!  Deadline for Term 1 Materials: Monday, March 9th!!  Test over Chemical Reactions next Friday, March 6 th !  ONE 25 pt test (no 15pt and 10pt) over Chemical Reactions  15pt on Chemical Naming  10pt on Chemical Bonding  Term Final – Wednesday and Thursday March 11 th and 12 th  10pt on Chemical Naming  Review Packet on Blog  Begin working through NOW!

4. Chemical Equations and Reactions  Chemical equations are used to show chemical reactions.  Indicators of a Chemical Reaction Include:  Change in color (unexpected)  Production/release of a gas (bubbles)  Change in temperature  Exothermic  Endothermic  Formation of a precipitate (solid)

5. Law of Conservation of Mass  Matter cannot be created nor destroyed, it can only change forms.  Chemical equations must ALWAYS be balanced to obey the law of conservation of mass.  Mass has to be the same on both sides of the reaction.  The number of atoms has to be the same for the products and reactants.  What you start with, you must end with

6. Components of a Chemical Equation  Reactants  Listed on the LEFT side of the equation.  Starting substances (ingredients)  Products  Listed on the RIGHT side of the equation.  Ending substances (produced substance)  Arrow  “Yields”  States of Matter  Solid (s)  Liquid (l)  Gas (g)  Aqueous (aq)  Coefficients  Whole number that proceeds the chemical substance (number of moles of the substance)

7. Steps to Follow to Balance Equations 1. Determine the number of atoms for each element. 2. Pick an element that is not equal on both sides of the equation. 3. Add a coefficient in front of the formula with that element and adjust your counts. 4. Continue adding coefficients to get the same number of atoms of each element on each side. **Note: LEAVE THE SUBSCRIPTS ALONE! (you cannot change the chemical formula to balance atoms)

8. Coefficients  Coefficients go in front of a compound 4H 2 O -All atoms in a compound are multiplied by the coefficient Number of atoms: Hydrogen- Oxygen-

9. Practice With Coefficients *List the amount of each atom in the 4 substances below: 4CH 4 3Ni(NO 3 ) 2 3NH 3 4Ca 3 (PO 4 ) 2

10. Class Examples - Model  See hand out for chemical formulas. Balancing Word Equations: (See additional steps on next slide)  Potassium chlorate  potassium chloride + oxygen  When solid copper reacts with aqueous silver nitrate, the products are aqueous copper (II) nitrate and silver metal.  Nitrogen and oxygen combine to form dinitrogen pentaoxide

11. Steps to Write Equations 1. When writing formulas don’t forget to look up charges if the compound is ionic!!! 2. Diatomic Molecules: Always travel in pairs 1. H.O.F.Br.I.N.Cl. (Dr. HOFINBrCl) 2. These elements need a subscript 2 after them if they are by themselves! 3. Once the equation is written, then balance the equation by adding coefficients.

12. Individual Practice Word problems:  Packet

13. Individual Practice  Unit Packet