Views: 8 Author: Anne Marie Helmenstine, Ph.D. Publish Time: 2019-12-17 Origin: ThoughtCo
How Many Elements Can Be Found Naturally?
by Anne Marie Helmenstine, Ph.D.
Updated September 02, 2019
There are 118 elements currently on the periodic table. Several elements have only been found in laboratories and nuclear accelerators. So, you may wonder how many elements can be found naturally.
The usual textbook answer is 91. Scientists used to believe that, except for the element technetium, all the elements up to element 92 (uranium) could be found in nature. However, it turns out there are other elements that occur in trace amounts naturally . This brings the number of naturally occurring elements to 98.
"New" Naturally Occurring Elements
Technetium is one of the newer elements added to the list. Technetium is an element with no stable isotopes. It is produced artificially by bombarding samples of molybdenum with neutrons for commercial and scientific uses and was widely believed to be nonexistent in nature. This has turned out to be untrue. Technetium-99 can be produced when uranium-235 or uranium-238 undergoes fission. Minute amounts of technetium-99 have been found in uranium-rich pitchblende.
Elements 93–98 (neptunium, plutonium, americium, curium, berkelium, and californium) were all first artificially synthesized and isolated in the Lawrence Berkeley National Laboratory at the University of California, Berkeley. They have all been found in the fallout of nuclear testing experiments and by products of the nuclear industry and were believed to exist only in man-made forms. This also turned out to be untrue. All six of these elements have been found in very small amounts in samples of uranium-rich pitchblende.
Perhaps one day, samples of element numbers greater than 98 will be identified.
List of Elements Found in Nature
The elements found in nature are elements with atomic numbers 1 (hydrogen) through 98 (californium). Ten of these elements occur in trace amounts: technetium (No. 43), promethium (61), astatine (85), francium (87) , neptunium (93), plutonium (94), americium (95), curium (96), berkelium (97), and californium (98).
The rare elements are produced by radioactive decay and other nuclear processes of more common elements. For example, francium is found in pitchblende as the result of alpha decay of actinium. Some elements found today may have been produced by the decay of primordial elements—elements produced earlier in the history of the universe that have since vanished.
Native vs. Natural Elements
While many elements occur in nature, they might not occur in pure or native form. There are only a few native elements. These include the noble gases, which don't readily form compounds, so they are pure elements. Some of the metals occur in native form, including gold, silver, and copper. Nonmetals including carbon, nitrogen, and oxygen occur in native form. Elements that occur naturally, yet not in native form, include the alkali metals, alkaline earth, and rare earth elements. These elements are found bound in chemical compounds, not in pure form.