Where does all the silicon on Earth come from?
Well, I am sure you have heard of the term “atom”.
Atoms are the building blocks of all the material
in the universe and they are made of little
particles called protons, neutrons and electrons.
There are many different types of atoms and the
type is determined by the number of protons. For
example hydrogen has one proton, helium has two,
and Lithium has three and so on. Silicon is
also a type of atom and has 14 protons.
When the universe was created in the big bang,
first there were only single protons flying
around. So there was only one type of atom
(hydrogen). New types of atoms can form when
protons get really hot, come together and join.
This is called nuclear fusion and creates a lot of
energy. In fact the sun shines because of hydrogen
joining together to make helium. When more and
more protons join together they form more and more
different types of atoms. Silicon with 14
protons is the 8th most abundant type of atom in
the universe so that means that there is quite a
lot of it.
Now we know how the different types of atoms
form but how did so much silicon from the
universe ended up on planet Earth?
Well, before the sun and the planets existed there
was just a giant cloud of different types of atoms
that formed a dust. The dust slowly came together
and started rotating faster and faster. More and
more dust particles became attracted to each
other, collided and formed larger and larger
bodies. That way the sun and the planets formed.
The sun was in the center and the planets were
rotating around it. But the sun was very, very hot
and many types of atoms could not survive in that
heat and were driven far away from the sun.
Only material that was mostly made of iron,
silicon and oxygen stayed close to the sun and
many of the other atoms were pushed further
away. Therefore, the planets that are close to
the sun (Mercury, Venus, Earth, Mars) are made of
mostly iron, silicon and oxygen and just small
numbers of the other types of atoms.
Now the last question that remains is where
did all the iron go? There is a little bit of
iron on the
Earth surface but is there so much more
silicon? Well, much of the iron, because it is
so much heavier than silicon, sank to the core of
the Earth, whereas the silicon stayed on the
outside. For that reason the rocks at the
surface of the Earth today are made out of a lot