Origins of the Earths Chemical Elements

Humans have espoused all manner of theories as to the origins of the universe—including philosophical, scientific, theological, and mystical myths, as well as just plain speculation— 

Another popular theory speculates that there was no beginning and there will be no end to the universe—it is infinite. Another theory is that there is continuous death and rebirth of stars and matter in the universe. Others postulate that it all started by some spontaneous and unknown force—possibly supernatural. 

We know a great deal about the nature of the universe. For instance, the element hydrogen makes up about 75% of all the mass in the universe. In terms of number, about 90% of all atoms in the universe are hydrogen atoms, and most of the rest of the atoms in the universe are helium. All the other heavier elements make up just one to two percent of the total. Interestingly, the most abundant element on Earth (in number of atoms) is oxygen (O ). Oxygen accounts for about 50% of all the elements found in the Earth s crust, and silicon, the second most abundant element, makes up about 25%. Silicon dioxide (SiO ) accounts for about 87% of the total Earth s mass. Sfiicon dioxide is the main chemical compound found in sand and rocks. 

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