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Chapter 7Chemical Formula Problems
I. Formulas and Formula Mass
A. The Number of Atoms in a formula
1) Determine the number of atoms of each element.
B. Calculating the Molecular Mass (or Formula Mass)
1) Atomic Mass: Average mass of atoms of an element
compared to atom of carbon12 as exactly 12 amu.
Atomic mass of Carbon = 12.01 amu
2) Molecular Mass: Average Mass of Molecules
compared to atom of carbon12 as exactly 12 amu.
3) Formula Mass: Average mass of formula units(ionic compounds)
compared to atom of carbon12 as exactly 12 amu.
4. Formula Mass= (funny looking E which means Mass) atomic masses in
formula unit
5. Examples: (In notebook)
II. The Mole Concept
A. Def: One mole is that amount of any substance that contains the
same number of units as the number of atoms in exactly 12 grams of
carbon12.
B. Avogadro's Number:
The number of particles in one mole.
This number is 6.02 x 10^23
C. Molar Mass
1. Def: Mass in grams of 1 mole of a substance
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View Full Document2. Elements
Examples: (In notebook)
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 Fall '08
 Staff
 Chemistry, Atom, Mole

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