![]() This table organizes the elements by increasing atomic number into rows (" periods") in which the columns (" groups") share recurring ("periodic") physical and chemical properties. ![]() Much of the modern understanding of elements developed from the work of Dmitri Mendeleev, a Russian chemist who published the first recognizable periodic table in 1869. Attempts to classify materials such as these resulted in the concepts of classical elements, alchemy, and various similar theories throughout human history. The history of the discovery and use of the elements began with primitive human societies that discovered native minerals like carbon, sulfur, copper and gold (though the concept of a chemical element was not yet understood). Air is primarily a mixture of the elements nitrogen, oxygen, and argon, though it does contain compounds including carbon dioxide and water. Nearly all other naturally occurring elements occur in the Earth as compounds or mixtures. Only a minority of elements, such as silver and gold, are found uncombined as relatively pure native element minerals. When different elements undergo chemical reactions, atoms are rearranged into new compounds held together by chemical bonds. This is in contrast to chemical compounds and mixtures, which contain atoms with more than one atomic number.Īlmost all of the baryonic matter of the universe is composed of chemical elements (among rare exceptions are neutron stars). For example, oxygen has an atomic number of 8, meaning that each oxygen atom has 8 protons in its nucleus. ![]() The basic particle that constitutes a chemical element is the atom, and each chemical element is distinguished by the number of protons in the nuclei of its atoms, known as its atomic number. Its availability limits the amount of life our planet can sustain.A chemical element is a chemical substance that cannot be broken down into other substances. Phosphorus, then, is nature’s bottleneck. Unlike carbon, which can be obtained from carbon dioxide, there is no phosphorus compound present in our surroundings that can serve as a convenient source. We need phosphorus for our bones and teeth, and it is a crucial component of all living cells. Phosphorus makes up 1.1% of the human body but only 0.105% of Earth’s crust. There is an element that we need more of in our bodies than is proportionately present in Earth’s crust, and this element is not easily accessible. Looking Closer: The Phosphorous Bottleneck On the other hand, although carbon is present in the atmosphere as carbon dioxide, and about 80% of the atmosphere is nitrogen, we obtain those two elements from the food we eat, not the air we breathe. We obtain oxygen from the air we breathe and the water we drink. How does the human body concentrate so many apparently rare elements? The relative amounts of elements in the body have less to do with their abundances on Earth than with their availability in a form we can assimilate. Oxygen has the highest percentage in both cases, but carbon, the element with the second highest percentage in the body, is relatively rare on Earth and does not even appear as a separate entry carbon is part of the 0.174% representing “other” elements. If you compare both compositions, you will find disparities between the percentage of each element in the human body and on Earth. \) also lists the relative abundances of elements in the human body.
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