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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 ...
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. Each of these names can be further abbreviated by a one- or two-letter chemical symbol; those for hydrogen, helium, and lithium are respectively H, He, and Li. [6]
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.
Americas, where the element was first synthesized, by analogy with its homolog europium: f-block groups 7 f-block [243] 12: 1449: 2880 – 1.13 – synthetic: solid 96 Cm Curium: Pierre and Marie Curie, physicists and chemists f-block groups 7 f-block [247] 13.51: 1613: 3383 – 1.28 – synthetic solid 97 Bk Berkelium: Berkeley, California ...
(at m.p.) 6.21 g/cm 3: 71 Lu lutetium; use: 9.3 g/cm 3: CR2 (at m.p.) 9.3 g/cm 3: 72 Hf hafnium; use: 12 g/cm 3: CR2 (at m.p.) 12 g/cm 3: 73 Ta tantalum; use: 15 g/cm 3: CR2 (at m.p.) 15 g/cm 3: 74 W tungsten; use: 17.6 g/cm 3: CR2 (at m.p.) 17.6 g/cm 3: 75 Re rhenium; use: 18.9 g/cm 3: CR2 (at m.p.) 18.9 g/cm 3: 76 Os osmium; use: 20 g/cm 3 ...
This small radius and high weight cause it to be expected to have an extremely high density of around 46 g·cm −3, over twice that of osmium, currently the most dense element known, at 22.61 g·cm −3; element 164 should be the second most dense element in the first 172 elements in the periodic table, with only its neighbor unhextrium ...
Here [Ne] refers to the core electrons which are the same as for the element neon (Ne), the last noble gas before phosphorus in the periodic table. The valence electrons (here 3s 2 3p 3) are written explicitly for all atoms. Electron configurations of elements beyond hassium (element 108) have never been measured; predictions are used below.
There are currently seven complete periods in the periodic table, comprising the 118 known elements. Any new elements will be placed into an eighth period; see extended periodic table. The elements are colour-coded below by their block: red for the s-block, yellow for the p-block, blue for the d-block, and green for the f-block.