1. Unit: Chemical Reactions
Day 1 - Notes
Unit: Chemical Reactions
Diatomic elements, Writing formula equations from word equations
Upper left: Thermite reaction, Fe2O3 + Al => 2Fe +2Al2O3 + HEAT!!!
Upper right: potassium in water, K + H2O => KOH + H2 + HEAT
Bottom right: potassium chlorate and sugar, C12H22O11 + 8KClO3 => 12CO2 + 11H2O + 8KCl + HEAT!!!
Bottom left: magnesium reacting with oxygen, Mg + O2 => MgO

2. After today you will be able to…
Name the diatomic elements
Write formula equations given the word equation for a chemical reaction
heat Pt

3. A chemical equation represents a chemical reaction.
Reactants  Products
“Yield”
Reactants and products are separated from each other with a plus (+) sign.

4. Common forms of chemical reactions…
A + B  C
A  B + C
A + B  C + D

5. Chemical equations can be written as word equations or formula equations. Formula equations can be balanced or unbalanced.

6. Word Equation: Iron + Oxygen  Iron (III) Oxide Formula Equation: 4Fe(s) + 3O2(g)  2Fe2O3(s)
Balanced!

7. Symbols in Chemical Equations
Meaning
(s)
Solid
(l)
Liquid
(g)
Gas
(aq)
Aqueous (dissolved in H2O) 
Reversible reaction
 or 
Heat is added 
Catalyst is added (A substance that speeds up a reaction.)
heat Pt

8. To change word equations into formula equations follow the flow chart…

9. ELEMENT? Monatomic Diatomic
Is the substance an…
ELEMENT?
Monatomic
Diatomic
Just write the symbol
Example:
“Sodium”=Na
Br2 I2 N2 Cl2 H2 O2 F2
Have the subscript “2”
Examples:
“Bromine”=Br2
“Hydrogen” = H2

10. Is the substance a… COMPOUND? CaCl2 N2O4 Ionic Molecular (M +nM)
(nM +nM)
Balance charges!!!
Example: “calcium chloride”
Ca+2 Cl-1
Cl-1
Prefixes for subscripts
Examples:
“dinitrogen tetraoxide”
CaCl2
N2O4

11. Let’s try some examples! 

12. Helpful tip: Keep all substances and + signs in
Examples: Convert into formula equations…
1. sodium chloride + fluorine  sodium fluoride + chlorine
2. aluminum + sulfur  aluminum sulfide
Helpful tip: Keep all substances and + signs in
line with each other!
Na Cl-1
Na F-1
NaCl + F2 
NaF +
Cl2
Al S-2 Al + S 
Al2S3

13. + Mg3(AsO4)2 ZnS  Zn3(AsO4)2 + MgS
3. zinc magnesium  zinc magnesium
Zn+2 S-2
Mg+2 (AsO4)-3
Zn+2 (AsO4)-3
Mg+2 S-2
sulfide arsenate arsenate sulfide +
Mg3(AsO4)2
ZnS 
Zn3(AsO4)2 +
MgS

14. Do now: Complete “Exit Ticket”
Then: Begin WS 1 (Homework)