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63. 64. Counting Atoms with Coefficient. Counting Atoms with Coefficients. 9/26/11. 10/16/2013. 10/16/2013. A pplication How many atoms 1 . Ba 3 (PO 4 ) 2 2 . 4Ba 3 (PO 4 ) 2 3 . Al 2 (Cr 2 O 7 ) 3 4 . 2Al 2 (Cr 2 O 7 ) 3 Connection : Counting Atoms with Coefficients Ws - PowerPoint PPT Presentation
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9/26/1164Counting Atoms with Coefficients
10/16/201363 Counting Atoms with Coefficient
10/16/2013
..
Starter:How many atoms are in the following compounds:
H2O, NaCl, Cl2
ApplicationHow many atoms1. Ba3(PO4)2
2. 4Ba3(PO4)2
3. Al2(Cr2O7)3
4. 2Al2(Cr2O7)3
Connection: Counting Atoms with Coefficients Ws Exit: What is the difference between a carbon dioxide (CO2) and carbon monoxide (CO)?.
Practice:
Chemical Formula
# of elements
# of atoms
NaCl
CO2
C6H12
HgOH
Ag2S
Li2O
October 15, 2013AGENDA8.5 D.
I will be able to recognize that chemical formulas identify substances and used to determine the number of atoms of each element in chemical formulas by reading, and writing while completing notes and activity
1 Starter2. Notes3. Activity4. Exit
Ca (H2PO4)2 H
2O
NaCl
C2H4O2
Date Lecture/ Activity/ Lab Page9/25 Metal, Nonmetals, and Metalloids 41-429/26 Where’s Al? 43-449/27 Element Wanted Poster 45-469/30 Bohr Model Challenge 47-4810/1 Periodic Table Notes/Puzzles 49-5010/2 Periodic Table Chart 51-5210/3 Test Review 53-5410/8 Test Corrections 55-5610/9 Molecules, Compounds, and Elements 57-5810/10 Build a Molecule Activity 59-6010/15 Counting Atoms 61-6210/16 Counting Atoms with Coefficients 63-64
Table of Contents
Practice Chemical Formula
# of elements # of atoms
NaCl
CO2
C6H12
HgOH
Ag2S
Li2O
2
22
3
2 18
3 3
2 3
23
Application:Counting Atoms with
Coefficients
To determine the number of atoms present,
MULTIPLY the subscript by the coefficient
Example
The coefficient for this compound is 3
3MgCl2
There are:
1 x 3 = 3 Mg
2 x 3 = 6 Cl
“Double” Subscripts
Sometimes ions have a “double” subscript
4Al(NO2)3
One subscript is INSIDE the parenthesis and one
subscript is OUTSIDE the parenthesis
“Double” SubscriptsTo count the number of atoms in a
compound with “double” subscripts, you must MULTIPLY the subscripts
4Al2(CO2)3
There are:
2 x 4 = 8 Al atoms
3 x 1 x 4 = 12 C atoms
3 x 2 x 4 = 24 O atoms
Total atoms = 44
This “3” applies to both C and O
This “2” applies only to the O
Example
The coefficient for this compound is 5
5Mg(OH)2
There are:
1 x 5 = 5 Mg2+ ions
2 x 1 x 5 = 10 O atoms
2 x 1 x 5 = 10 H atoms
Total atoms = 25
More Examples
1. How many of each atom in Ba3(PO4)2?
2. How many of each atom in 4Ba3(PO4)2?
3. How many of each atom in Al2(Cr2O7)3?
4. How many of each atom in 2Al2(Cr2O7)3?
Answers
1. 3-Ba, 2-P, 8-0= 132. 12-Ba, 8-P, 32-O= 523. 2-Al, 6-Cr, 21-O= 294. 4-Al, 12-Cr, 42-O= 58
.
9/26/1164Counting Atoms with Coefficients
10/16/201363 Counting Atoms with Coefficient
10/16/2013
..
Starter:How many atoms are in the following compounds:
H2O, NaCl, Cl2
ApplicationHow many atoms1. Ba3(PO4)2
2. 4Ba3(PO4)2
3. Al2(Cr2O7)3
4. 2Al2(Cr2O7)3
Connection: Counting Atoms with Coefficients Ws Exit: What is the difference between a carbon dioxide (CO2) and carbon monoxide (CO)?.
Practice:
Chemical Formula
# of elements
# of atoms
NaCl
CO2
C6H12
HgOH
Ag2S
Li2O
