Natural chemical elements are those that are found in nature, they are not produced by man or in laboratories. There are 118 different elements currently on the periodic table; several elements have only been found in laboratories and nuclear accelerators.
So, anyone can wonder how many elements there are that can be found naturally. The usual textbook answer is 91. Scientists used to believe that, with the exception of the element technetium, all elements up to element 92 (uranium) could not be found in nature.
Of the 118 elements discovered, there are 90 elements that occur in nature in appreciable quantities. There are 8 other elements that occur in nature as a result of radioactive decay of heavier elements.
However, it turns out that there are other elements that occur in trace amounts naturally. This brings the number of natural elements to 98. As new decay patterns are discovered, the number of natural elements is likely to grow.
80 elements have at least one stable isotope. The other 38 elements only exist as radioactive isotopes. Several of the radioisotopes instantly break down into a different element.
Technocium is one of the newer items added to the list. Technetium is an element without stable isotopes. It is produced artificially by bombarding molybdenum samples with neutrons for commercial and scientific uses and was widely believed not to exist in nature.
This has turned out not to be true. Technetium-99 can be produced when uranium-235 or uranium-238 undergo fission. Minimal amounts of technetium -99 have been found in uranium-rich pitch.
Elements 93-98 (neptunium, plutonium, americium, curium, berchium, and californium) were all artificially synthesized and isolated at the Berkeley Radiation Laboratory of the University of California.
They have all been found in the rain of nuclear test experiments and by-products of the nuclear industry and were believed to exist only in man-made forms. This also turned out to be uncertain.
All six of these elements have been found in very small quantities in samples of uranium rich in pitchblende.
One day samples of item numbers greater than 98 may be identified.
Chemical elements found in nature
The elements found in nature are elements with atomic numbers from 1 (hydrogen) to 98 (californium).
Ten of these elements can be found, albeit briefly, in nature, in extremely minute quantities: technetium (number 43), promethium (number 61), astatine (number 85), francium (number 87), neptunium (number 93), plutonium (number 94), americium, curium (number 96), berkelium (number 97) and californium (number 98).
Rare elements are produced by radioactive decay and other nuclear processes of more common elements. For example, francium is found in pecblende as a result of the alpha decay of actinium.
Some elements found today may have been produced by the decay of primordial elements, which are elements produced earlier in the history of the universe that have since disappeared.
Here is a list of the natural elements, with their respective symbols. Colors refer to where they are found on the periodic table:
Elements are detected in stars, nebulae, and supernovae from their spectra. Although practically the same elements are found on Earth compared to the rest of the universe, the proportions of the elements and their isotopes are different.
Non-native natural elements
While many elements occur in nature, they may not occur in a pure or native form. Actually, there are only a few native elements.
These include the noble gases, which do not easily form compounds, so they are pure elements. Some of the metals are produced natively, including gold, silver, and copper.
Nonmetals including carbon, nitrogen, and oxygen occur natively. Elements that occur naturally, but not natively include the alkali metals, alkaline earths, and rare earth elements. These elements are united in chemical compounds, not in pure form.