Today
You will need
a calculator!
Go get it
Counting Atoms
What are some ways that we make it
easier to count groups of things?
Atoms and molecules are tiny...
 Counting groups is a pain in the back.
 18 grams of water contain 602 000 000 000 000 000 000
000 molecules (more or less...)
 How can we make this easier?
1 mole = 6.023 x 1023 items
We still don’t want to count the things!
The mass of one mole is the
MOLAR MASS
1 mole of iron
= 602 000 000 000 000 000 000
000 atoms
= 55.85 grams
Posters around the room...
 Lists of Elements and Compounds, with their
Molar Mass
 I did NOT give any hint as to how I found the
molar mass.
 You know how to look up mass on the periodic
table for each atom.
 You have 5 minutes to look at the posters and
figure out what you would need to do.
Oxygen
O2
32.00 grams/mole
Water
H2O
18.02 grams/mole
Calcium chloride
CaCl2
110.98 grams/mole
Sodium chloride
NaCl
58.44 grams/mole
Fluorine gas
F2
38.00 grams/mole
Sulfur
S8
256.56 grams/mole
Baking Soda
NaHCO3
56.54 grams/mole
Potassium permanganate
KMnO4
158.04 grams/mole
It seemed that...