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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 ...
This is a list of chemical elements and their atomic properties, ordered by atomic number (Z).. Since valence electrons are not clearly defined for the d-block and f-block elements, there not being a clear point at which further ionisation becomes unprofitable, a purely formal definition as number of electrons in the outermost shell has been used.
At high pressure formation of TcH 1.3 from elements was also reported. [33] TcCl 4 forms chain-like structures, similar to the behavior of several other metal tetrachlorides. The following binary (containing only two elements) technetium halides are known: TcF 6, TcF 5, TcCl 4, TcBr 4, TcBr 3, α-TcCl 3, β-TcCl 3, TcI 3, α-TcCl 2, and β-TcCl 2.
The following molar volumes and densities for the majority of the gaseous elements were calculated from the van der Waals equation of state, using the quoted values of the van der Waals constants. The source for the van der Waals constants and for the literature densities was: R. C. Weast (Ed.), Handbook of Chemistry and Physics (53rd Edn ...
Platinum is a chemical element; it has symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Its name originates from Spanish platina, a diminutive of plata "silver". [7] [8] Platinum is a member of the platinum group of elements and group 10 of the periodic table of ...
The (C 5 H 5) − ion in samarium cyclopentadienides can be replaced by the indenide (C 9 H 7) − or cyclooctatetraenide (C 8 H 8) 2− ring, resulting in Sm(C 9 H 7) 3 or KSm(η(8)−C 8 H 8) 2. The latter compound has a structure similar to uranocene .
It is to be expected that the electronegativity of an element will vary with its chemical environment, [7] but it is usually considered to be a transferable property, that is to say that similar values will be valid in a variety of situations. Caesium is the least electronegative element (0.79); fluorine is the most (3.98).
A chemical element is a chemical substance whose atoms all have the same number of protons.The number of protons is called the atomic number of that element. For example, oxygen has an atomic number of 8, meaning each oxygen atom has 8 protons in its nucleus.