There are 118 elements in the periodic table. We might think that we are made up of many of them. In reality, the complex systems that support the human body have a surprisingly simple elemental composition.
The Periodic Table of Elements is an organized arrangement of the 118 currently known chemical elements. These are arranged from left to right and top to bottom in increasing order of atomic number (number of protons in the nucleus) which generally coincides with increasing atomic mass.
The horizontal rows of the table are called periods, and each period number indicates the number of orbitals for the elements in that row. An atomic orbital is a mathematical term that describes the location of an electron as well as its wave behavior.
The columns (or groups) of the periodic table represent the atomic elements that have the same number of valence electrons or the electrons of the outermost orbital shell. These elements behave similarly chemically. For example, all group 18 elements are so-called "inert" gases that do not react with any other element.
That being said, how many of these elements fit into our body? There are several dozen of them, but four of them largely dominate, making up about 97% of our body weight . These are oxygen, carbon, hydrogen and nitrogen.
In this sample, oxygen represents between 65% and 67% of the human body by weight . This is not very surprising since we are made up of about 60% water. Oxygen is also essential for energy production and metabolism, and other chemical processes.
Carbon ranks second (about 18% to 19% of the body by weight). This element, which is a major component of most terrestrial life forms , forms the backbone of fats, carbohydrates and proteins.
Hydrogen comes next. The other component of H2O along with oxygen is also a key component of proteins, carbohydrates and fats. Note that there are more hydrogen atoms in the human body than any other element. On the other hand, it only represents 9 to 10% of our body by mass. Indeed, oxygen and carbon have atomic weights that are respectively nearly sixteen and twelve times greater.
Finally, nitrogen makes up about 3% of the human body by weight. This element is essential for proteins and their building blocks, called amino acids. Nitrogen is also a major component of DNA and RNA . In other words, without this element, the cells of our body could neither store genetic information nor replicate.
