Moles, Molecules and Grams
A quick review!
National Mole Day
October 23rd from
6:02 a.m. to 6:02 p.m.
Established by a high school
chemistry teacher, Maurice
Oehler, in 1991.
National Mole Day is celebrated around the world
to engage young minds in the study of chemistry.
Amedeo Avogadro
6.02 x
23
10
Things to understand about
Avogadro's number
• It is a huge number, far greater in magnitude than we
can visualize.
• Its practical use is limited to counting tiny things like
atoms, molecules, "formula units", electrons, or
photons.
• It is a number, just like a "dozen", and thus is
dimensionless; you can think of Avogadro's number
as the "chemist's dozen".
There are 12 eggs in a dozen:
12 eggs =
There are 6.02 x 1023 molecules in a mole:
=
Example:
#12 from your worksheet
How many grams are there in 1 x 1024 molecules
of BCl3?
1) Find the molar mass of BCl3
1 x B atom: 1 x 10.811 =
10.811
3 x Cl atoms: 3 x 35.453 =
106.359
117.17 g/mol
Example:
#12 from your worksheet
How many grams are there in 1 x 1024 molecules
of BCl3?
2) Set up your conversions
1 x 1024 molecules
x
1 mole
x
6.02 x 1023 molecules
117.17 grams of BCl3
1 mole
Example:
#12 from your worksheet
How many grams are there in 1 x 1024 molecules of
BCl3?
3) Do your calculations and cross off your units
1 x 1024 molecules
x
1 mole
x
6.02 x 1023 molecules
= 194.63 grams of BCl3
117.17 grams of BCl3
1 mole
Conversion
Nomenclature
A quick review!
Naming Binary Compounds
• A Metal and a Non-Metal....
Name of Metal + Non-Metal with suffix “ide”
Ex:
CaCl
Calcium Chloride
Naming Binary Compounds
• A Non-Metal and a Non-Metal....
(prefix) non-metal + (prefix) non-metal with
suffix “ide”
Note: if the prefix of the 1st non-metal is mono,
then we do NOT write it
Ex:
CO2
Carbon dioxide
Writing the Chemical Formula
• The cross over rule.....
2+
N
3O
N3O2