Chapter 4 - Calculations & Chemical Equations

Chapter 4 - Calculations & Chemical Equations




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,↑ Chapter 4 - Calculations & Chemical Equations

4.1 - The Mole Concept & Atoms

Atoms are exceedingly small

The mass of the atom is measured using amu (Atomic Mass Unit)

Carbon-12 is assigned the mass of exactly 12 amu

1 amu = 1.66 x 10−24 g/amu

Chemists usually work with much larger quantities, it is more convenient to work with grams
than amu when using larger quantities




The Mole and Avogadro’s Number

Mole: A practical unit for defining a collection of atoms

Avogadro's Number: 1 mole of atoms = 6.022 x 1023 atoms/mol

This has provided the basis for the concept of the mole

A mole (mol) is simply a unit that defines an amount of something, like the dozen defines 12
of something




Atomic Mass

The atomic mass of one atom of an element corresponds to

The average mass of a single atom in amu
The mass of a mole of atoms in grams

1 atom of F is 19.00 amu 19.00 amu/atom F

1 mole of F is 19.00g 19.00 g/mole F




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, Conversions Between the Units




What to memorize to solve any problem

1 amu = 1.66 x 10−24 g/amu

1 mol = 6.022 x 1023 atoms/mol

Molar Mass = g/mol (from the periodic table)




Practice




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