1. Try on your own and write answers on the board…
Daily Opener Questions
Try on your own and write answers on the board…

2. Fill in answers!

3. Chemical Reactions Take Place…
Every minute of every day both in and around you
Examples:
Digestion
Photosynthesis
Car batteries-to start your car
Rust

4. Reactions:
One or more substances, the ___________ change into one or more new substances, the __________.
It is written as:
Reactants → Products
The arrow means
“yields” or “reacts to produce”
reactants
products

5. Chemical Reactions
A Balancing Act

6. Explanation:
An explanation was proposed by _____________ who stated in his atomic theory that in a chemical reaction, the way in which atoms are joined together are changed.
As reactants are converted to new products, __________that hold atoms together are __________ and new ones are formed.
Dalton
bonds
broken

7. Law of Conservation of Mass
Explanation:
Daltons atomic theory explains the ____________________________.
Which States:
In any physical or chemical change mass is neither created nor destroyed.
The atoms in the products are the same atoms that were in the reactants, they are just arranged differently.
Law of Conservation of Mass

8. Explanation/Practice:
In a word equation, reactants are written on the ___________ and products are written on the ________.
Write the equation for…
Copper can be produced by heating copper (II) sulfide with oxygen. Sulfur dioxide is also produced.
Water is formed by the explosive reaction between hydrogen and oxygen
left
right

9. Answers Copper(II)sulfide + Oxygen → Copper + Sulfer dioxide
Hydrogen + Oxygen → Water (Dihydrogen monoxide)

10. Meaning of Chemical Formula
Symbol Meaning Composition
H2O One molecule
of water:
Two H atoms and one O atom
2 H2O Two molecules
of water:
Four H atoms and two O atoms
H2O2 One molecule
of hydrogen
peroxide:
Two H atoms and two O atoms

11. Meaning of Chemical Formula
When a __________ is written after the chemical symbol for an element it indicates the___________________.
When a coefficient is written in front of an atom or molecule it indicates the ____________ of that atom or molecule that is present.
If there are subscripts in that atom/molecule they need to be ____________ by the coefficient.
subscript
# of that element
number
multiplied

12. Reactants  Products Unbalanced
Timberlake, Chemistry 7th Edition, page 164

13. Unbalanced and Balanced EquationsH Cl Cl H H Cl H Cl Cl Cl H Cl H H
H2 + Cl2  HCl (unbalanced)
H2 + Cl2  2 HCl (balanced)
reactants products
reactants products H H Cl Cl
Timberlake, Chemistry 7th Edition, page 167

14. How do we go from Unbalanced to Balanced Equations?
You ____________ change the formula of your atom/ion/molecule!
This means you may not change the ___________ !
Instead, you may put a coefficient __________ of your atom/ion/molecule to balance the number of atoms after you have ___________ it by the subscript
MAY NOT
subscript
in front
multiplied

15. CH4 + 2 O2  CO2 + 2 H2O Balanced! Reactants Products
1 C atom C atom
4 H atoms H atoms
4 O atoms O atoms
Balanced!
Timberlake, Chemistry 7th Edition, page 167

16. Coefficient  subscript = # of atoms
Balancing Steps
1. Write the unbalanced equation.
2. Count atoms on each side.
3. Add coefficients as needed to make #s equal on both sides of the equation.
Coefficient  subscript = # of atoms
4. Reduce coefficients to lowest possible ratio, if necessary.
5. Double check atom balance!!!

17. Helpful Tips Balance one element at a time.
Update ALL atom counts after adding a coefficient.
If an element appears more than once per side, balance it last.
Balance polyatomic ions as single units.
“1 SO4” instead of “1 S” and “4 O”

18. Balancing Example 2 Al + CuCl2  Cu + AlCl3 Al Cu Cl 3 3 2 2  1 1 2 3
Aluminum and copper(II) chloride react to form copper and aluminum chloride. 2
Al CuCl2  Cu AlCl3 Al Cu Cl 3 3 2
2 
 2
 6
3 
6 
 3

19. More Examples… P + O2 → P4O10 H2 + O2 → H2O BaCl2 + H2SO4→ BaSO4 + HCl
Cu + AgNO3 → Cu(NO3) Ag
CaCO HCl → CaCl2 + H2CO3 5 2 2 2 2 2 2

20. When writing Chemical Rxns…
It is important to indicate what “state” the atom/molecule is in
(s): solid
(l): liquid
(g): gas
(aq): aqueous solution – a solution in which the solvent is water
∆: heat