counting atoms
DESCRIPTION
COUNTING ATOMS. RULES FOR COUNTING ATOMS. SUBSCRIPTS only refer to the atom that they are BEHIND . For example… H 2 S There are TWO atoms of HYDROGEN and only ONE atom of SULFUR. COEFFICIENTS. - PowerPoint PPT PresentationTRANSCRIPT
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COUNTING ATOMS
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RULES FOR COUNTING ATOMS
1. SUBSCRIPTS only refer to the atom that they are BEHIND. For example…
H2SThere are TWO atoms of HYDROGEN and only ONE atom of SULFUR.
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COEFFICIENTS
2. COEFFICIENTS apply to the entire compound. You MULTIPLY the coefficients and SUBSCRIPTS.
2 H2S
ATOMS OF HYDROGEN:
ATOMS OF SULFUR:
4
2
IF THERE ISN’T A SUBSCRIPT BEHIND AN ELEMENT, ASSUME THERE IS ONLY ONE ATOM OF THAT ELEMENT!
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PARENTHESES
3. If elements or compounds are inside of PARENTHESES, then the SUBSCRIPT behind the parentheses applies to everything inside.
Ba(OH)2
ATOMS OF BARIUM:
ATOMS OF OXYGEN:
ATOMS OF HYDROGEN:
1
2
2
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LET’S PRACTICE!LET’S PRACTICE!
MgCl2
Atoms of Magnesium:
Atoms of Chlorine:
1
2
Al2S3
Atoms of Aluminum:
Atoms of Sulfur:
23
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PRACTICEPRACTICE
H2SO4
Atoms of Hydrogen:Atoms of Sulfur:Atoms of Oxygen:
21
CH3OH
Atoms of Carbon:
Atoms of Hydrogen:
Atoms of Oxygen:
14
4
1
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THIS COULD BE A LITTLE THIS COULD BE A LITTLE TRICKY…TRICKY…
Ca3(PO4)2 Atoms of Calcium:Atoms of Phosphorus:Atoms of Oxygen:
32
Al2(SO4)3
Atoms of Aluminum:
Atoms of Sulfur:
Atoms of Oxygen:
23
8
12
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What about this BAD BOY???What about this BAD BOY???
2Ca3(PO4)2 Atoms of Calcium:Atoms of Phosphorus:Atoms of Oxygen:
64
16