&").! $%/"! $%! %
0!1"&Dierent types: ;
Example of Natural Change: Great Oxidation Event; Greatest chemical change. GOE is where free oxygen into
our atmosphere. It was caused by cyanobacteria doing photosynthesis. It took a very long time, from about
three billion years ago to about one billion years ago. Photosynthesis was producing oxygen both before and after
the GOE. The difference was that before the GOE, organic matter and dissolved iron chemically captured any
free oxygen. Dissolved iron (of which there was a great deal) became iron oxide and huge deposits of this are
found as banded iron rock from the Archaean and Proterozoic eras. The GOE was the point when these minerals
became saturated and could not capture any more oxygen. The excess free oxygen started to accumulate in the
A Life drastically altered the composition of the surface of the earth.
Air Pollution: winds distribute pollutants. Sources of Mercury are distributed in the air by two main sources:
Human (greater emissions by humans such as coal burning power plants and waste incinerators) and Natural
(biomass burning and volcanic). Dominating air currents circulate these emissions to the arctic and other areas
around the world.
Formation and Evolution of The Universe:
The universe was created from a very small, dense conglomeration of mater and energy (called
singularity) that then exploded. This was known as the Big Bang! (10-15bya, an explosion of the dense
center of matter into a titanic fireball). The universe is made up of space and time, all forms of matter,
energy and momentum, and physical laws that govern these.
Aftermath of the Big Bang:
Hot cloud containing only Hydrogen (98%) and Helium (2%)
Gases clump into separate clouds forming a nebulae
Collapse of a nebulae leads to formation of protostars.
In the enormous gaseous cloud, created when the universe began, smaller cloud of H and He formed.
These clouds of gases condensed under gravitational pull and contracted into swirling tubular masses of
material that eventually would become galaxies. The spinning cosmic clouds fragmented further and
smaller masses (protostars) formed within them. During their evolution, protostars contracted under
gravitational pill and became denser. Their temperatures rose and nuclear fusion reactions began within
When fusion of Hydrogen produces Helium until hydrogen is used up A then fusion of Helium to form
heavier atoms until helium is consumed A then the formation of Iron (Fe) in large stars.
A supernova occurs when a very massive star runs out of fuel and an energetic explosion occurs such that
elements heavier then Fe are formed. A death of a star leaves the universe with heavier elements left
behind to mix with residual gas from the big bang.