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Chlorine. orthorhombic (oS8) Chlorine is a chemical element; it has symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is a yellow-green gas at room temperature. It is an extremely reactive element ...
Isotopes of chlorine. Chlorine (17 Cl) has 25 isotopes, ranging from 28 Cl to 52 Cl, and two isomers, 34m Cl and 38m Cl. There are two stable isotopes, 35 Cl (75.8%) and 37 Cl (24.2%), giving chlorine a standard atomic weight of 35.45. The longest-lived radioactive isotope is 36 Cl, which has a half-life of 301,000 years.
Chlorine-36. Chlorine-36 (36 Cl) is an isotope of chlorine. Chlorine has two stable isotopes and one naturally occurring radioactive isotope, the cosmogenic isotope 36 Cl. Its half-life is 301,300 ± 1,500 years. [1] 36 Cl decays primarily (98%) by beta-minus decay to 36 Ar, and the balance to 36 S. [1] Trace amounts of radioactive 36 Cl exist ...
Prout's hypothesis. Prout's hypothesis was an early 19th-century attempt to explain the existence of the various chemical elements through a hypothesis regarding the internal structure of the atom. In 1815 [1] and 1816, [2] the English chemist William Prout published two papers in which he observed that the atomic weights that had been measured ...
The mass number should also not be confused with the standard atomic weight (also called atomic weight) of an element, which is the ratio of the average atomic mass of the different isotopes of that element (weighted by abundance) to the atomic mass constant. [9] The atomic weight is a mass ratio, while the mass number is a counted number (and ...
The atomic mass (ma or m) is the mass of an atom. Although the SI unit of mass is the kilogram (symbol: kg), atomic mass is often expressed in the non-SI unit dalton (symbol: Da) – equivalently, unified atomic mass unit (u). 1 Da is defined as 1⁄12 of the mass of a free carbon-12 atom at rest in its ground state. [1]
The rule is a modified version of Prout's hypothesis proposed in 1815, to the effect that atomic weights are multiples of the weight of the hydrogen atom. [2] It is also known as the Aston whole number rule[3] after Francis W. Aston who was awarded the Nobel Prize in Chemistry in 1922 "for his discovery, by means of his mass spectrograph, of ...
The first of these quantities is used in atomic physics, the second in chemistry, but both refer to the same basic property of the element. To convert from "value of ionization energy" to the corresponding "value of molar ionization energy", the conversion is: 1 eV = 96.48534 kJ/mol. 1 kJ/mol = 0.0103642688 eV [12]