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Chem. Atmosphere
Early Atmosphere
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Cards (21)
Why are there many theories of the early atmosphere?
Little
evidence
Time scale of
4.6
billion years
Main theory of Evolution Early Atmosphere
During the first billion years of Earth's existence, there was intense
volcanic
activity /
eruptions.
This released
gases
that formed the early
atmosphere.
How were oceans formed?
Water vapour
in the atmosphere cooled and
condensed
to form
oceans.
The temperature fell below
100
degrees.
Gases present in the Early Atmosphere :
Water
Vapour
Nitrogen
Methane
Ammonia
Early Earth's similarity with Venus and Mars today :
Consisting of mainly
carbon dioxide
gas
Little or no
oxygen
gas
How Volcanoes gradually produced Nitrogen, Methane and Ammonia?
intense
volcanic
eruptions
including
small
proportions of
methane
and
ammonia
Other ways Nitrogen had formed?
Ammonia
in the
Earth's
early atmosphere reacted with
oxygen
Dissolution of carbon dioxide in the oceans :
Decreasing
carbon dioxide
Carbon dioxide
dissolved
in
oceans
Carbon dioxide precipitate forming sediments
This reduced the amount of carbon dioxide in the atmosphere
Describe and explain how the surface of the early Earth and its atmosphere have changed to form the surface of the Earth and its atmosphere today (6)
Oxygen
increased = plants /
algae
developed using carbon dioxide for
photosynthesis
, producing
oxygen.
Thus, carbon dioxide
decreased.
Water vapour
in the atmosphere cooled and
condensed
to form oceans.
Carbon dioxide
decreased
because carbon dioxide
dissolved
in oceans. Carbon dioxide became
locked
up in
sedimentary
rocks.
Nitrogen
formed because
ammonia
from early atmosphere reacted with
oxygen
Explain how carbon dioxide is released from limestone.
Calcium
carbonate
Thermal
decomposition
How oxygen increased?
Algae
and
plants
produced oxygen
NOW
in the atmosphere by
photosynthesis.
Word equation for photosynthesis
Carbon dioxide
+
water
-->
glucose
+
oxygen
Symbol equation for photosynthesis (balanced)
6CO2
+ 6H20 -->
C6H12O6
+ 6O2
First presence of Algae
First produced
oxygen
about
2.7
billion years ago.
Oxygen
presence
Soon after
algae
,
oxygen
appeared in the
atmosphere
Plant evolution
Over the next
billion
years, plants evolved and the percentage of
oxygen
gradually
increased.
Increased to a
level
that enabled animals to
evolve.
2 ways carbon dioxide has decreased
Plants and
algae
developed using carbon dioxide for
photosynthesis
,
decreasing
the level of carbon dioxide in the atmosphere.
Dissolved
into oceans. Carbon dioxide become
locked
up in
sedimentary
rocks.
Fossil fuels and carbon dioxide
Carbon dioxide
decreased
because it
dissolved
into oceans. Carbon dioxide became
locked
up in
fossil
fuels.
One reason why nitrogen has increased overtime
Very
unreactive
Coal, Crude Oil, Natural Gas
Fossil fuels
The percentage of argon in the Earth’s atmosphere today is the same as it was in the Earth’s early atmosphere. Suggest why.
Argons
gas is
unreactive
/
inert
A
noble
gas = Group
0