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Platinum also has 38 synthetic isotopes ranging in atomic mass from 165 to 208, making the total number of known isotopes 44. The least stable of these are 165 Pt and 166 Pt, with half-lives of 260 μs, whereas the most stable is 193 Pt with a half-life of 50 years. Most platinum isotopes decay by some combination of beta decay and alpha decay. 188
Alternately, the atomic mass of a carbon-12 atom may be expressed in any other mass units: for example, the atomic mass of a carbon-12 atom is 1.992 646 882 70 (62) × 10 −26 kg. As is the case for the related atomic mass when expressed in daltons , the relative isotopic mass numbers of nuclides other than carbon-12 are not whole numbers, but ...
A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [ 1 ] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...
Naturally occurring platinum (78 Pt) consists of five stable isotopes (192 Pt, 194 Pt, 195 Pt, 196 Pt, 198 Pt) and one very long-lived (half-life 4.83×10 11 years) radioisotope (190 Pt). There are also 34 known synthetic radioisotopes, the longest-lived of which is 193 Pt with a half-life of 50 years. All other isotopes have half-lives under a ...
The Earth's crust is one "reservoir" for measurements of abundance. A reservoir is any large body to be studied as unit, like the ocean, atmosphere, mantle or crust. Different reservoirs may have different relative amounts of each element due to different chemical or mechanical processes involved in the creation of the reservoir. [1]: 18
Just as atomic units are given in terms of the atomic mass unit (approximately the proton mass), the physically appropriate unit of length here is the Bohr radius, which is the radius of a hydrogen atom. The Bohr radius is consequently known as the "atomic unit of length". It is often denoted by a 0 and is approximately 53 pm. Hence, the values ...
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This number was chosen so that if an element has an atomic mass of 1 u, a mole of atoms of that element has a mass close to one gram. Because of the definition of the unified atomic mass unit, each carbon-12 atom has an atomic mass of exactly 12 Da, and so a mole of carbon-12 atoms weighs exactly 0.012 kg. [65]