A chemical element is any substance that cannot be chemically separated into simpler substances. They are made up of a single type of atom and are distinguished by the atomic number, which is the amount of protons found in the nucleus of the element. All elements also have a chemical symbol, such as Mg for magnesium and Na for sodium, which is used on the periodic table and in chemical equations. Currently there are 118 known elements, but not all of these occur naturally.
How many elements in the periodic table are naturally occurring?
Of the 118 elements that are known only the first 94 have been found naturally on Earth. However, 6 of these elements (technetium, promethium, astatine, francium, neptunium and plutonium) are not stable and have a relatively short half life. They may been found in trace amounts in nature due to cosmic rays, nuclear tests or in uranium ore, but they do not remain in the environment for very long. This means that the answer to the question is not straightforward. We can say that 88 elements are naturally occurring in larger than trace amounts and 94 elements have been found naturally on Earth.
Did you know?
Although the debate exists on the number of naturally occurring elements, most textbooks state that 92 elements are naturally occurring. This is due to the fact that neptunium and plutonium are usually considered synthetic elements even though trace amounts are sometimes found in uranium ores.
Astatine, which only occurs through the decay of heavier elements, is considered to be the rarest naturally occurring element at less than an ounce in the Earth’s crust at any time. Francium is the second rarest naturally occurring element in nature and is found in uranium and thorium ores. It is estimated that there is only 20-30 g (about an ounce) of it at any time in the crust of the Earth. Both of these elements decay away rapidly and the most stable isotope of francium has a half life of just 22 minutes.