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Krypton (from Ancient Greek: κρυπτός, romanized: kryptos 'the hidden one') is a chemical element; it has symbol Kr and atomic number 36. It is a colorless, odorless noble gas that occurs in trace amounts in the atmosphere and is often used with other rare gases in fluorescent lamps .
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 periodic table and law are now a central and indispensable part of modern chemistry. The periodic table continues to evolve with the progress of science. In nature, only elements up to atomic number 94 exist; [a] to go further, it was necessary to synthesize new elements in the laboratory.
There are 34 known isotopes of krypton (36 Kr) with atomic mass numbers from 67 to 103. Naturally occurring krypton is made of five stable isotopes and one (78 Kr) which is slightly radioactive with an extremely long half-life, plus traces of radioisotopes that are produced by cosmic rays in the atmosphere.
Mass number [294] Oganesson in the periodic table; ... Krypton: Rubidium: Strontium: Yttrium: Zirconium: ... On the periodic table of the elements it is a p-block ...
For other isotopes, the isotopic mass is usually within 0.1 u of the mass number. For example, 35 Cl (17 protons and 18 neutrons) has a mass number of 35 and an isotopic mass of 34.96885. [7] The difference of the actual isotopic mass minus the mass number of an atom is known as the mass excess, [8] which for 35 Cl is –0.03115.
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.
Krypton is less reactive than xenon, but several compounds have been reported with krypton in the oxidation state of +2. [40] Krypton difluoride is the most notable and easily characterized. Under extreme conditions, krypton reacts with fluorine to form KrF 2 according to the following equation: Kr + F 2 → KrF 2