Back to the Top of the Page Oxygen is not just used by our bodies for respiration . It is the most abundant element on earth and is a part of almost everything. It's not just in the air. Half of the weight of the entire planet earth is oxygen. About 89 percent of the total weight of the ocean is oxygen.
Most common rocks are about half oxygen by weight.
And about 65 percent of the weight of your body is oxygen . Of course, a great deal of that oxygen in our bodies is in water which has one oxygen atom and two hydrogen atoms in each molecule. But it is also a key ingredient of many other molecules. Of Your whole body is mostly made of just 6 different types of atoms - carbon , hydrogen , oxygen , nitrogen , sulfur , and phosphorous . There are, of course, a few other minerals here and there, but the above elements make up about 98 percent of the human body.