Transcript 2.8 Atoms, Molecules & the Atmosphere Notes

2.8 Atoms, Molecules, and the
Atmosphere
• Every person on the planet earth needs air
to breathe. But, have you ever wondered
what air is made up of?
• Take a minute and write down what you
think makes up air.
• Now, write down the corresponding
percentages for each component of air.
Atoms, Molecules, and the
Atmosphere
• Here are the actual components of air:
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–
–
–
Oxygen
Nitrogen
Argon (Ar)
Carbon Dioxide (CO2)
Oxygen
• Atoms of oxygen can combine to form two
different molecules:
• O2 is oxygen gas. It makes up 21% of air.
• and O3 is ozone. It is formed naturally in the
upper layers of the atmosphere.
• Ozone is important since it absorbs most of the
ultraviolet radiation from the Sun.
• The ozone layer is being destroyed by CFCs or
chlorofluorocarbons.
Nitrogen
• Nitrogen makes up 78.02% of the
atmosphere.
• It is not very reactive, which means we can
inhale it without causing chemical changes
in our lungs.
• We do not want to inhale nitrogen dioxide
since it is a very toxic gas.
Argon
• Argon gas is completely harmless.
• Almost all of the argon in the atmosphere
has leaked out from inside the Earth.
• Argon is used for filling electric light bulbs
and fluorescent tubes.
• Argon and other gases make up 0.94% of
the atmosphere.
Carbon Dioxide CO2
• When fossil fuels burn, the two main
products are carbon dioxide and water.
• Carbon dioxide is used by plants.
• Carbon dioxide makes up 0.03% of the
atmosphere.
Carbon Monoxide (CO)
• Produced during combustion when there is a lack
of oxygen. For example, if you use a propane
barbecue indoors, or if you run an automobile
inside a closed garage.
• The CO molecule is similar to the oxygen
molecule in that when carbon monoxide enters
the lungs, the body’s red blood cells treats it the
same as oxygen and carries it throughout the
body. The cells of the body are then starved of
the oxygen they need and you could die.
Answering Questions about
Various Molecules
By looking at the chemical formula of a molecule
we can answer a variety of questions such as:
• Which elements are required to construct the molecule?
• How many atoms, in total, are required to construct the
molecule?
• How many atoms, of each element, are required to
construct the molecule?
• What is the ratio of each type of atom in the molecule?
• What is the mass of each molecule?
An Example
C9H8O4 or Aspirin
• Which elements are required to construct the molecule?
C = Carbon H = Hydrogen O = Oxygen
• How many atoms, in total, are required to construct the
molecule?
9 + 8 + 4 = 21 total atoms in one molecule of Aspirin
• How many atoms, of each element, are required to
construct the molecule?
9 Carbon, 8 Hydrogen and 4 Oxygen atoms are required
to construct one molecule of Aspirin.
An Example
C9H8O4 or Aspirin
• What is the ratio of each type of atom in the molecule?
9/21 is Carbon 8/21 is Hydrogen 4/21 is Oxygen
• What is the mass of each molecule?
Mass of one molecule of aspirin is calculated as follows:
(atomic mass C) x 9
(atomic mass H) x 8
+ (atomic mass O) x 4
(12) x 9
(1) x 8
(16) x 4
108
8
64
180
The atomic mass of one molecule of Aspirin is 180.
An Example - You do it!
Theobromine (Chocolate) - C7H8N4O2
• Which elements are required to construct the molecule?
• How many atoms, in total, are required to construct the
molecule?
• How many atoms, of each element, are required to
construct the molecule?
• What is the ratio of each type of atom in the molecule?
• What is the mass of each molecule?
An Example - You do it!
Theobromine (Chocolate) - C7H8N4O2
• Which elements are required to construct the molecule?
C = Carbon H = Hydrogen N = Nitrogen O = Oxygen
• How many atoms, in total, are required to construct the
molecule?
7 + 8 + 4 + 2 = 21 total atoms in one molecule of Chocolate
• How many atoms, of each element, are required to
construct the molecule?
7 Carbon, 8 Hydrogen, 4 Nitrogen and 2 Oxygen atoms are
required to construct one molecule of Chocolate.
An Example
Theobromine (Chocolate) - C7H8N4O2
• What is the ratio of each type of atom in the molecule?
7/21 is Carbon 8/21 is Hydrogen 4/21 is Nitrogen and
2/21 is Oxygen
• What is the mass of each molecule?
Mass of one molecule of chocolate is calculated as follows:
(atomic mass C) x 7
(atomic mass H) x 8
(atomic mass N) x 4
+ (atomic mass O) x 2
(12) x 7
(1) x 8
(14) x 4
(16) x 2
84
8
56
32
180
The atomic mass of one molecule of chocolate is 180.
Assignment
• Do the “Counting Atoms” worksheet that’s
in the shared file
– For the molecules containing calcium,
aluminum and chromium calculate the atomic
mass also.
• Hand in the worksheet and then move on.
• Questions 1, 2 and 4 on page 61