Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Why is the Earth made up of so much silicon?

  1. Dec 21, 2008 #1
    Why is the Earth made up of so much silicon?
  2. jcsd
  3. Dec 21, 2008 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Re: Silicon

    The chemical composition of the earth is determined by the composition of the debris cloud from which the solar system formed. These debris are "cinders" of stellar furnaces and perhaps a super nova or 2. Iron is the true cinders of stellar fires as there is no release of energy on either fusion or fission of an iron nuclei.
  4. Dec 23, 2008 #3
    Re: Silicon

    But why is the Earth made of such a high proportion of silicon? Would all other rock planets have a similiar composition of silicon?
  5. Dec 23, 2008 #4


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Re: Silicon

    Are you talking about the abundance of silicon in Earth's crust? I believe it is roughly 16% by weight in the crust and about 9-10% in the whole earth. Iron is about 1.5% in the crust and about 46% in the whole earth. Earth is mostly iron. Lighter elements like the various oxides of silicon tend to float on top and have hardened into crust.
  6. Dec 24, 2008 #5
    Re: Silicon

    I am talking about the composition of the Earth, not taking into account atmospheric composition. From wikipedia....The mass of the Earth is approximately 5.98×1024 kg. It is composed mostly of iron (32.1%), oxygen (30.1%), silicon (15.1%), magnesium (13.9%), sulphur (2.9%), nickel (1.8%), calcium (1.5%), and aluminium (1.4%); with the remaining 1.2% consisting of trace amounts of other elements.....

    looking at the table below which I found, I am curious as to why there is so much silicon on Earth?

    most common elements in the universe

    Element (Parts per million – mg per kg)
    1 Hydrogen 750,000
    2 Helium 230,000
    3 Oxygen 10,000
    4 Carbon 5,000
    5 Neon 1,300
    6 Iron 1,100
    7 Nitrogen 1,000
    8 Silicon 700
    9 Magnesium 600
    10 Sulphur 500

    SOURCE: The Top 10 of Everything 2006 by Russell Ash, page 10
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Why is the Earth made up of so much silicon?
  1. Why is the earth so big? (Replies: 13)