A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus.[1] Common examples of elements are iron, copper, silver, gold, hydrogen, carbon, nitrogen, and oxygen. All chemical matter consists of these elements.
Save for the hydrogen and helium in the universe, which are thought to have been mostly produced in the Big Bang, most chemical elements are thought to have been produced by later processes.
These processes are divided into:
* cosmic ray spallation (important for lithium, beryllium and boron, though some of these may have formed in the Big Bang), and
* stellar nucleosynthesis which produces all elements heavier than boron (with carbon being the first of this series). The very heaviest elements (those beyond element 94, plutonium) decay with half lives too short to allow them to be observed naturally on Earth.
Timberland Boots Sale
Baltimore accident lawyer
Subject: Chemical element 
Mon Nov 29, 2010 1:57 pm
