1. COUNTING ATOMS

2. RULES FOR COUNTING ATOMS
_____ only refer to the atom that they are _____. For example…
H2S
There are ___ atoms of ___ and only ___ atom of ___.

3. COEFFICIENTS
___ apply to the entire compound. You ___ the coefficients and ___.
2 H2S
ATOMS OF HYDROGEN:
ATOMS OF SULFUR: __ __
IF THERE ISN’T A SUBSCRIPT BEHIND AN ELEMENT, ASSUME THERE IS ONLY ONE ATOM OF THAT ELEMENT!

4. PARENTHESES
3. If elements or compounds are inside of ___, then the ___ behind the parentheses applies to everything inside.
Ba(OH)2
ATOMS OF BARIUM:
ATOMS OF OXYGEN:
ATOMS OF HYDROGEN: __ __ __

5. LET’S PRACTICE! MgCl2 Atoms of Magnesium: Atoms of Chlorine: __ __
Al2S3
Atoms of Aluminum:
Atoms of Sulfur: __ __

6. PRACTICE __ __ __ CH3OH Atoms of Carbon: Atoms of Hydrogen: __
H2SO4
Atoms of Hydrogen:
Atoms of Sulfur:
Atoms of Oxygen: __ __ __
CH3OH
Atoms of Carbon:
Atoms of Hydrogen:
Atoms of Oxygen: __ __ __

7. THIS COULD BE A LITTLE TRICKY…
Ca3(PO4)2
Atoms of Calcium:
Atoms of Phosphorus:
Atoms of Oxygen: __ __ __
Al2(SO4)3
Atoms of Aluminum:
Atoms of Sulfur:
Atoms of Oxygen: __ __ __

8. What about this BAD BOY??? 2Ca3(PO4)2 Atoms of Calcium:
Atoms of Phosphorus:
Atoms of Oxygen: __ __ __