Atomic mass
• The atomic mass is the average mass of
an atom.
When using
atomic masses
make sure to
round to at least
one decimal
place.
What is the
atomic mass of
actinium (Ac)?
227.0278
227.0
What is the
atomic mass of
hydrogen (H)?
1.00794
1.0
What is the mass
of hydrogen (H2)?
2.0
Vitamin A: C20H30O
• The first of the 13 vitamins to be discovered,
it plays a vital role in the growth and repair of
body tissues, and is particularly important in
maintaining good eyesight and healthy skin,
as well as aiding in bone and teeth formation.
• Vitamin A-rich foods include: Liver, sweet
potatoes, carrots, mangoes, spinach,
cantaloupe, dried apricots, milk, egg yolks,
mozzarella cheese.
Determine the
Molecular Mass of
Vitamin A
C20H30O
20 x 12.0 = 240.0
30 x 1.0 = 30.0
1 x 16.0 = 16.0
= 286.0 amu
H
H2O
NaCl
• H is an atom and it would therefore have an
atomic mass.
• H2O is a molecule and it would therefore have
a molecular mass.
• NaCl is neither an atom or a molecule and
would therefore have a formula mass.
Formula Mass
• The formula mass is the mass of an ionic
compound.
• An ionic compound is formed from a
combination of metals and nonmetals.
• Formula masses are calculated the same
as molecular masses.
Determine the
Formula Mass of
Calcium Phosphate
Ca3(PO4)2
3 x 40.1 = 120.3
2 x 31.0 = 62.0
8 x 16.0 = 128.0
= 310.3 amu
Chapter 8: The Mole – Part 1
What is Avogadro’s favorite saying
from American History?
The Mole
• A mole is Avogadro’s number of particles, that
is 6.02 × 1023 particles.
• 1 mol = Avogadro’s Number
= 6.02 × 1023 particles
How Big is a Mole?
• Where would you need
to go to see 1 mole of
rice grains?
How Big is a Mole?
• 1 mole of rice grains is
more than the number
of rice grown since the
beginning of time?
How Big is a Mole?
• The worlds fastest supercomputer can count the
world’s population in ¼ second. How long would
it take this computer to count to 1 mole?
How Big is a Mole?
• The worlds fastest supercomputer can count the
world’s population in ¼ second. It would take this
computer 1.9 million years to count to 1 mole?
How Big is a Mole?
One mole of marbles would cover the entire Earth
(oceans included) for a depth of three miles.
One mole of $100 bills stacked one on top of another
would reach from the Sun to Pluto and back 7.5 million
times.
It would take light 9500 years to travel from the
bottom to the top of a stack of 1 mole of $100 bills.
How Big is a Mole?
• Where would you
need to go to see
1 mole of water.
World’s Fastest Super Computer
vs.
Super Teacher
The Marble Contest
What is the mass in grams of
exactly 1 mole of water?
• 1.66 x 10-24 g/amu
1 mol H2O
What is the mass in grams of
exactly 1 mole of water?
• 1.66 x 10-24 g/amu
1 mol H2O 6.02 x 1023 H2O molecules
mol H2O
What is the mass in grams of
exactly 1 mole of water?
• 1.66 x 10-24 g/amu
1 mol H2O 6.02 x 1023 H2O molecules 18.0 amu
mol H2O
molecule H2O
What is the mass in grams of
exactly 1 mole of water?
• 1.66 x 10-24 g/amu
1 mol H2O 6.02 x 1023 H2O molecules 18.0 amu
mol H2O
molecule H2O
1.66 x 10-24 g
amu
What is the mass in grams of
exactly 1 mole of water?
• 1.66 x 10-24 g/amu
1 mol H2O 6.02 x 1023 H2O molecules 18.0 amu
mol H2O
molecule H2O
1.66 x 10-24 g
amu
= 18.0 g
1 mol H2O = 18.0g
• This is the gram formula mass of water.
• This is the molar mass of water.
• The gram formula mass (molar mass) is
the molecular mass of the substance in
grams.
What is the mass of
1 mol sucrose (C12H22O11)
1 mol sucrose (C12H22O11) = 342.0g
• 12 x 12.0 = 144.0
• 22 x 1.0 = 22.0
• 11 x 16.0 = 176.0
gfm = 342.0 g
Homework
• Molecular and Formula Mass Worksheet
(due in two days).
• Don’t forget to show your work on your
calculations.
Why 6.02 x
23
10
• How did scientists come up with such a random
number for the mole?
• It’s really not random at all. It is really just
based on a ratio that you already know.
• 1.66 x 10-24 g/amu.
Why 6.02 x
23
10
• How many atoms are in exactly one mole
of carbon?
Why 6.02 x
23
10
• How many atoms are in exactly one mole of
carbon?
1 mol C
Why 6.02 x
23
10
• How many atoms are in exactly one mole of
carbon?
1 mol C
12.0 g C
mol
Why 6.02 x
23
10
• How many atoms are in exactly one mole of
carbon?
1 mol C
12.0 g C
mol
1 amu
1.66 x 10-24 g
Why 6.02 x
23
10
• How many atoms are in exactly one mole of
carbon?
1 mol C
12.0 g C
mol
1 amu
1.66 x 10-24 g
C atom
12.0 amu
Why 6.02 x
23
10
• How many atoms are in exactly one mole of
carbon?
1 mol C
12.0 g C
mol
1 amu
1.66 x 10-24 g
C atom
12.0 amu
= 6.02 x 1023 C atoms/mol
Why 6.02 x
23
10
• How many atoms are in exactly one mole of
carbon?
1 mol C
12.0 g C
mol
1 amu
1.66 x 10-24 g
C atom
12.0 amu
= 6.02 x 1023 C atoms/mol
Why 6.02 x
23
10
• How many atoms are in exactly one mole of
carbon?
1
1.66 x 10-24
= 6.02 x 1023
Why 6.02 x
23
10
• How many molecules are in exactly one
mole of water?
Why 6.02 x
23
10
• How many molecules are in exactly one mole of
water?
1 mol H2O
Why 6.02 x
23
10
• How many molecules are in exactly one mole of
water?
1 mol H2O 18.0 g H2O
mol
Why 6.02 x
23
10
• How many molecules are in exactly one mole of
water?
1 mol H2O 18.0 g H2O
mol H2O
1 amu
1.66 x 10-24 g
Why 6.02 x
23
10
• How many molecules are in exactly one mole of
water?
1 mol H2O 18.0 g H2O
mol
1 amu
1.66 x 10-24 g
H2O molecule
18.0 amu
Why 6.02 x
23
10
• How many molecules are in exactly one mole of
water?
1 mol H2O 18.0 g H2O
mol
1 amu
1.66 x 10-24 g
H2O molecule
18.0 amu
= 6.02 x 1023 H2O molecules/mol
Why 6.02 x
23
10
• How many molecules are in exactly one mole of
water?
1 mol H2O 18.0 g H2O
mol
1 amu
1.66 x 10-24 g
H2O molecule
18.0 amu
= 6.02 x 1023 H2O molecules/mol
Why 6.02 x
23
10
• How many molecules are in exactly one mole of
water?
1
1.66 x 10-24
= 6.02 x 1023