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The periodic table is a graphic description of the periodic law, which states that the properties and atomic structures of the chemical elements are a periodic function of their atomic number. Elements are placed in the periodic table according to their electron configurations , [41] the periodic recurrences of which explain the trends in ...
List of chemical elements. 118 chemical elements have been identified and named officially by IUPAC. 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]
Graphs of abundance vs atomic number. Abundance (atom fraction) of the chemical elements in Earth's upper continental crust as a function of atomic number; [5] siderophiles shown in yellow. Graphs of abundance against atomic number can reveal patterns relating abundance to stellar nucleosynthesis and geochemistry .
Rare-earth elements occur in nature in combination with phosphate ( monazite ), carbonate - fluoride ( bastnäsite ), and oxygen anions. In their oxides, most rare-earth elements only have a valence of 3 and form sesquioxides (cerium forms CeO2 ). Five different crystal structures are known, depending on the element and the temperature.
Table of nuclides. A table or chart of nuclides is a two-dimensional graph of isotopes of the elements, in which one axis represents the number of neutrons (symbol N) and the other represents the number of protons (atomic number, symbol Z) in the atomic nucleus. Each point plotted on the graph thus represents a nuclide of a known or ...
Blocks (s, p, d, f, ...) A block of the periodic table is a set of elements unified by the atomic orbitals their valence electrons or vacancies lie in. [1] The term seems to have been first used by Charles Janet. [2] Each block is named after its characteristic orbital: s-block, p-block, d-block, f-block and g-block .
The Gmelin rare earths handbook lists 1522 °C and 1550 °C as two melting points given in the literature, the most recent reference [ Handbook on the chemistry and physics of rare earths, vol.12 (1989)] is given with 1529 °C. The World Book encyclopedia from 2002 lists 1529 °C. 89 Ac actinium (Ac-227 ?)
Iron is a chemical element; it has symbol Fe (from Latin ferrum 'iron') and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's outer and inner core.
The standard atomic weight of a chemical element (symbol Ar° (E) for element "E") is the weighted arithmetic mean of the relative isotopic masses of all isotopes of that element weighted by each isotope's abundance on Earth. For example, isotope 63 Cu ( Ar = 62.929) constitutes 69% of the copper on Earth, the rest being 65 Cu ( Ar = 64.927), so.
Eka-tantalum is actually the synthetic superheavy element dubnium (105). Mendeleev's 1869 table had implicitly predicted a heavier analog of titanium (22) and zirconium (40), but in 1871 he placed lanthanum (57) in that spot. The 1923 discovery of hafnium (72) validated Mendeleev's original 1869 prediction. Mendeleev [6] Modern names.