Transcript Document

CPO Science
Integrated Physics &
Chemistry
Chapter 19.2
Chemical Formulas
Developing A Model
 Why is the periodic table of
elements arranged this way?
Read Part 1 of the investigation
Developing A Model
 What is an element’s oxidation number?
— Electrons gained of lost to become a stable ion
Atoms
Valence
Electrons
K
Mg
Al
P
Se
Br
Ar
Electron gained or Valence
lost during
Electrons
ionization
After
Oxidation
Number
1
2
3
1 lost
2 lost
8
8
+1
+2
3 lost
8
+3
5
3 gained
8
-3
6
2 gained
-2
7
1 gained
8
0 gained
8
8
8
-1
0
Key Questions
 Why do atoms combine in certain
ratios?
 What role does oxidation numbers
play?
 How do you name compounds?
Developing An Experiment
 What happens when a positive ion
comes in contact with a negative
ion?
— Opposites attract
— What charge does a Na ion have? How
do you know?
— What charge does a Cl ion have? How
do you know?
— Together they make?
The compound NaCl
Run The Experiment
Tips
Complete the chart for part 2.
Make sure to use the the tiles.
Remember the oxidation numbers
must add to zero
What did you learn?
 What role do the oxidation numbers play
in creating a compound?
 Why didn’t lithium & argon create a
compound?
 What did you notice about the ratio of
MgS?
— It was the lowest ratio
Naming Compounds
 These are the rules for ionic
compounds.
Now name the compounds you
created in part 2
Summary
 What are oxidation numbers?
 Why do atoms combine in certain
ratios?
 How do you name ionic compounds?