All Acronyms. CTA - Control Terminal Agency [Internet]; April 13, 2017 [cited 2017 APR 13]. Available from: https://www.allacronyms.com/CTA/Control_Terminal_Agency.
There are almost 120 known elements. For example, you are made up of billions of billions of atoms but you probably won't find more than 40 elements (types of atoms) in your body. Chemists have learned that over 95% of your body is made up of hydrogen (H), carbon (C), nitrogen, oxygen, phosphorus (P), and calcium (Ca).
Over the past two centuries, we have gained a much better understanding of the atomic elements and how they have formed. One of the things we have learned is that weâand every other living thing on Earthâare made up mostly of four elements. These four atomic elements are oxygen, carbon, hydrogen, and nitrogen. Together they make up about 96% of our bodies, as you can see in the figure.