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| | Abundance of the chemical elements - ExampleProblems.com |
 | | The Solar System was created from the remnants of previous stellar systems that went supernova, and is hence, relative to the rest of the universe, richer in heavier elements. |
 | | The six very rare, highly radioactive elements (polonium, astatine, francium, radium, actinium and protactinium) have such low natural abundances that they are not included or their natural adundances are not known as they are so low. |
 | | See sea water for abundance of elements in the ocean, but note that that list is by mass - a list by molarity would look very different, especially as regards the first 4 elements; specifically, hydrogen would comprise well over half of such a list. |
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