1. UNIT 6 Chemical Reactions You Will Need The Following: Chromebook - Notebook Reference Tables

2. Pre-Assessment: Work w/ Shoulder Buddy
What are the 4 indicators a chemical reaction has taken place?
____H2 (g) +____ O2 (g) ➔_______H2O (g)
Use balanced equation above to complete the chart:
What are the reactants?
What are the products?
How many oxygen atoms start the reaction?
How many oxygen atoms end the reaction?
Which substance(s) are gases in the reaction above?

3. Objectives By the end of today’s class you will be able to:
Recall the 4 signs of a chemical reaction
Identify the parts of a chemical equation
Understand the 1st Law of Conservation of Matter
Identify diatomic elements
Balance Chemical Equations

4. Warm up
After 24.0 days, 2.00 milligrams of an original milligram sample remain. What is the half-life of the sample?
How many electrons are in the 3rd shell (energy level) of an atom with an atomic number of 23?
Correct ALL Errors….
Cr2(SO3)3 = Dichromium sulfide
4. Identify the Alkaline Earth Metal in Period 3.
5. Write the noble gas notation for the Period 5 Halogen

5. What is a Chemical Reaction?
A change in the arrangement of atoms. New substances are formed ..

6. What is a chemical equation?
Chemical equation – Written description of a chemical change. Shows the atoms present in the reactants and rearrangement of atoms to form products
Parts of an equation:
Reactant
Product
2Ag + H2S
Ag2S + H2
Yields or Produces

7. Symbols Symbol Meaning + Plus or reacts with → Yields or Produces
(s) Solid
(l) Liquid
(g) or Gas
(aq) Aqueous (dissolved in water)
Δ Heat is added to the reaction

8. Diatomics – in elemental form there are 2 atoms bonded together .
H2, N2, O2, F2, Cl2, Br2, I2
Tricks to remember
I Bring Clay For Our New House
Or: Start at 7, make a 7, add hydrogen

9. Tricks to remember the DIATOMIC ELEMENTS
I Bring Clay For Our New House Or: Start at 7, make a 7, add hydrogen H N O F Cl Br I

10. Reactants and Products
Reactant - The chemical(s) you start with before the reaction.
Written on left side of equation.
Product - The new chemical(s) formed by the reaction.
Right side of equation.

11. Subscripts and Coefficients
Subscript - shows how many atoms of an element are in a molecule.
EX: H2O
2 atoms of hydrogen (H)‏
1 atom of oxygen (O)‏
Coefficient - shows how many molecules there are of a particular chemical.
EX: 2 H2O
Means there are 2 water molecules.

12. A Chemical Reaction
2H2 + O2  2H2O

13. Law of Conservation of Mass
In a chemical reaction, MATTER is neither created nor destroyed.
In other words, the number and type of atoms going INTO a rxn must be the same as the number and type of atoms coming OUT.
If an equation obeys the Law of Conservation, it is balanced.

14. Watch and Learn
Watch the video through 6 minutes -guide-balancing-equations/

15. An Unbalanced Equation
CH4 + O2  CO2 + H2O
Reactant Side
Product Side
1 carbon atom
4 hydrogen atoms
2 oxygen atoms
1 carbon atom
2 hydrogen atoms
3 oxygen atoms

16. A Balanced Equation CH4 + 2O2  CO2 + 2H2O Reactant Side Product Side
1 carbon atom
4 hydrogen atoms
4 oxygen atoms
1 carbon atom
4 hydrogen atoms
4 oxygen atoms

17. Rules of the Game
1. Matter cannot be created or destroyed. 2. Subscripts cannot be added, removed, or changed. 3. You can only change coefficients. 4. Coefficients can only go in front of chemical formulas...NEVER in the middle of a formula.

18. A few extra tips:
If the same polyatomic ion appears on both sides of the equation, it’s usually okay to treat it as one unit.
Sometimes it is useful to write water as H(OH) to balance with an hydroxide ion
Balance elements (single or diatomic) LAST
THIS IS A TRIAL AND ERROR PROCESS
Be Patient!

19. Balancing Equations 3 2 2 2 1 6 2 6 3 N2 + H2  NH3 N H
Balance the following equation by adjusting coefficients.
N H2  NH3 3 2
reactants
products N 2 2 1 6 2 6 3 H

20. Balancing Equations 3 2 2 2 1 1 2 2 1 2 1 6 3 2 6 KClO3  KCl + O2 K
Balance the following equation by adjusting coefficients. 3 2
KClO3  KCl + O2 2
reactants
products K 2 1 1 2 Cl 2 1 2 1 6 3 2 6 O

21. Simple Balancing
____ P4 + ____ O2  ____ P2O5

22. Simple Balancing
____ Ag2O  ____ Ag + ____ O2

23. You Try!!! ____ S8 + ____ O2  ____ SO3
____ K + ____ MgBr2  ____ KBr + ____ Mg

24. Equations with Polyatomic Ions
__ AgNO3 + __ MgCl2  __ AgCl+ __ Mg(NO3)2

25. You Try!!!
____ FeCl3 + ____ NaOH 
____ Fe(OH)3 + ____ NaCl

26. Combustion Reactions ____ CH4 + ___ O2  ___ CO2 + ___ H2O
Balance the atoms alphabetically
____ CH4 + ___ O2  ___ CO2 + ___ H2O

27. Combustion Reactions ____ C6H6 + ___ O2  ___ CO2 + ___ H2O
THIS ONE IS A STINKER!!
____ C6H6 + ___ O2  ___ CO2 + ___ H2O

28. Practice using the phet simulation https://phet. colorado
Practice using the phet simulation chemical-equations/latest/balancing-chemical- equations_en.html

29. EXIT TICKET __SeCl6 + __O2  __SeO2 + __Cl2
__ KCl __ CaCO3  __ CaCl2 + __ K2CO3

30. HOMEWORK Balancing Equations WS 1 Identify Reactants & Products: all
Balance The Equations: Even #s Only

31. Review and Practice Atom Math Nuclear Decay Periodic Behavior
Periodic Trends (Ordering Elements)
Lewis Structures
Mole Math