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9/26/1162Counting Atoms

10/15/201361 Counting Atoms

10/15/2013

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Starter:How many elements are in the following compounds:H2O, NaCl, Cl2

ApplicationHow many atoms1.2.3.4.5.Connection: Counting Atoms Ws

Exit: How does a chemical formula help us know what atoms are in a compound? Explain in 2-3 complete sentences.

Practice: Subscript Coefficients

1. 1.

2. 2.

3. 3.

example example

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 61-62

Table of Contents

Coefficients and Subscripts

6H2O + 6CO2 C6H12O6+ 6O2

Water + Carbon Dioxide Sugar + Oxygen

Why Do We Use Chemical Formulas and Equations?

Scientists use equations to show: how a chemical reaction took place

what elements were involvedwhat was produced from the reaction

Subscripts• small numbers behind the element

symbol• Show how atoms of an element

there are.

6H2O + 6CO2 C6H12O6+ 6O2

2 hydrogen atoms 6 carbon atoms

Subscripts•Subscripts show the number

of atoms

H2H4

H3

Coefficients

• are added to the front of a formula • show how many molecules of the

compound there are

6H2O + 6CO2 C6H12O6+ 6O2

6 water molecules 6 Oxygen molecules

Coefficients

Coefficients show the number of molecules.

4H2O 2H2O3H2O

How Many Atoms?

•NaCl

•Fe2O3

2 1 sodium

1 chlorine

5 2 Iron

3 oxygen

How Many Atoms?

•H3 PO4

•NaC2H3O3

3 hydrogen

1 phosphorus

4 oxygen 8

1 sodium 2 carbon3 hydrogen3 oxygen

9

How Many Atoms?

• (CH3)2 CO3 Carbon

6 Hydrogen

1 Oxygen 10

Add on back of sheet  

H2SO4  

   

 

 Ca(PO4)2  

 

 

HCl   

 

 

CaCO3  

 

 

 C2H4O2

  

 

.

9/26/1162Counting Atoms

10/15/201361 Counting Atoms

10/15/2013

..

Starter:How many elements are in the following compounds:H2O, NaCl, Cl2

ApplicationHow many atoms1.2.3.4.5.Connection:

Counting Atoms Ws

Exit: How does a chemical formula help us know what atoms are in a compound? Explain in 2-3 complete sentences.

Practice: Subscript Coefficients

1. 1.

2. 2.

3. 3.

example example