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[4] [5] Their natural occurrence is the result of cosmic ray spallation of carbon, nitrogen and oxygen in a type of nuclear fission reaction. The elements from carbon to iron are relatively more abundant in the universe because of the ease of making them in supernova nucleosynthesis. Elements of higher atomic numbers than iron (element 26 ...
In physics, natural abundance (NA) refers to the abundance of isotopes of a chemical element as naturally found on a planet. The relative atomic mass (a weighted average, weighted by mole-fraction abundance figures) of these isotopes is the atomic weight listed for the element in the periodic table. The abundance of an isotope varies from ...
The abundance of elements in Earth's crust is shown in tabulated form with the estimated crustal abundance for each chemical element shown as mg/kg, or parts per million (ppm) by mass (10,000 ppm = 1%).
The synthetic elements are those with atomic numbers 95–118, as shown in purple on the accompanying periodic table: [1] these 24 elements were first created between 1944 and 2010. The mechanism for the creation of a synthetic element is to force additional protons into the nucleus of an element with an atomic number lower than 95.
Chemical elements may also be categorized by their origin on Earth, with the first 94 considered naturally occurring, while those with atomic numbers beyond 94 have only been produced artificially via human-made nuclear reactions. Of the 94 naturally occurring elements, 83 are considered primordial and either stable or weakly
Today, 118 elements are known, the first 94 of which are known to occur naturally on Earth at present. [10] [a] The remaining 24, americium to oganesson (95–118), occur only when synthesized in laboratories. Of the 94 naturally occurring elements, 83 are primordial and 11 occur only in decay
Additionally, about 31 nuclides of the naturally occurring elements have unstable isotopes with a half-life larger than the age of the Solar System (~10 9 years or more). [b] An additional four nuclides have half-lives longer than 100 million years, which is far less than the age of the Solar System, but long enough for some of them to have ...
Thus, about two-thirds of stable elements occur naturally on Earth in multiple stable isotopes, with the largest number of stable isotopes for an element being ten, for tin (50 Sn). There are about 94 elements found naturally on Earth (up to plutonium inclusive), though some are detected only in very tiny amounts, such as plutonium-244.