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Neptunium is a chemical element; it has symbol Np and atomic number 93. A radioactive actinide metal, neptunium is the first transuranic element . It is named after Neptune , the planet beyond Uranus in the Solar System, which uranium is named after.
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 ...
Ausenium (atomic symbol Ao) and hesperium (atomic symbol Es) were the names initially assigned to the transuranic elements with atomic numbers 93 and 94, respectively. The discovery of the elements, now discredited, was made by Enrico Fermi and a team of scientists at the University of Rome in 1934.
Each distinct atomic number therefore corresponds to a class of atom: these classes are called the chemical elements. [5] The chemical elements are what the periodic table classifies and organizes. Hydrogen is the element with atomic number 1; helium, atomic number 2; lithium, atomic number 3; and so on.
List of elements by atomic properties. ... This is a list of chemical elements and their atomic properties, ordered by atomic number (Z). ... 0.93: 5.13908: 180: 227 ...
The darker more stable isotope region departs from the line of protons (Z) = neutrons (N), as the element number Z becomes larger. This is a list of chemical elements by the stability of their isotopes. Of the first 82 elements in the periodic table, 80 have isotopes considered to be stable. [1] Overall, there are 251 known stable isotopes in ...
where Z is the atomic number, and α is the fine-structure constant, a measure of the strength of electromagnetic interactions. [96] Under this approximation, any element with an atomic number of greater than 137 would require 1s electrons to be traveling faster than c, the speed of light. Hence, the non-relativistic Bohr model is inaccurate ...
Six of these occur in extreme trace quantities: technetium, atomic number 43; promethium, number 61; astatine, number 85; francium, number 87; neptunium, number 93; and plutonium, number 94. These 94 elements have been detected in the universe at large, in the spectra of stars and also supernovae, where short-lived radioactive elements are ...