The Comparative Abundance of The Elements
By Derrick Deacon
- There are 92 naturally occurring elements, only 17 of them make up 99.5% of the earth's crust (including oceans and atmosphere). - In living things (plants, animals, people) the six most abundant elements are carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur. - The universe is dominated by the elements hydrogen (83%) and helium (16%)
1. The Crust
The outside of the earth is a thin crust which is approximately 20 to 40km thick. The crust is a formation of dips and hollows which are filled with water to form the oceans and seas. On top of the earth's crust is an atmosphere, this is a thin layer of gases, 95% of these gases are within the first 20km of the earth's surface. Of the 17 elements that make up 99.5%, the most abundant of these are Oxygen 49.2%, Silicon 25%, and Aluminum 7.5%. Then the next most abundant elements are Iron 4.7%, Calcium 3.4%, Sodium 2.6%, Potassium 2.4%, Magnesium 1.9%, Hydrogen 0.9%, titanium 0.6%, Chlorine 0.2%, Phosphorus Manganese and Carbon are all 0.1%, Sulfur 0.05% Barium 0.04%, Nitrogen 0.03% and the rest of the elements on the periodic table take up about 0.5%.
The elements of the crust are graphed below, but only ones that are the most abundant due to the fact that the abundance of the other elements of the crust are too low to graph accurately on one graph.
Almost all elements are found as compounds, however Oxygen, Nitrogen, and to a lesser extent sulfur, gold, silver and platinum are the only elements which can be found in almost there raw sate. The atmosphere contains Oxygen and nitrogen, but it only contains a small portion of the earth's oxygen, this is because most of the world's oxygen is found in water, oxides of metals, and as silicates. Common soils and clays are silicates.
2. Living Things
In living things (plants, animals, people) the six most abundant elements are carbon, hydrogen, oxygen, nitrogen,...
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