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Helium at low temperatures is used in cryogenics and in certain cryogenic applications. As examples of applications, liquid helium is used to cool certain metals to the extremely low temperatures required for superconductivity, such as in superconducting magnets for magnetic resonance imaging.
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.
Elements are placed in the periodic table according to their electron configurations, [38] the periodic recurrences of which explain the trends in properties across the periodic table. [39] An electron can be thought of as inhabiting an atomic orbital, which characterizes the probability it can be found in any particular region around the atom.
Boca Raton, Florida, 2003; Section 6, Fluid Properties; Critical Constants. Also agrees with Celsius values from Section 4: Properties of the Elements and Inorganic Compounds, Melting, Boiling, Triple, and Critical Point Temperatures of the Elements Estimated accuracy for Tc and Pc is indicated by the number of digits.
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.
Main-group elements (with some of the lighter transition metals) are the most abundant elements on Earth, in the Solar System, and in the universe. Group 12 elements are often considered to be transition metals; however, zinc (Zn), cadmium (Cd), and mercury (Hg) share some properties of both groups, and some scientists believe they should be ...
Helium and neon are also used as refrigerants due to their low boiling points. Industrial quantities of the noble gases, except for radon, are obtained by separating them from air using the methods of liquefaction of gases and fractional distillation. Helium is also a byproduct of the mining of natural gas.
The properties of the elements are often summarized using the periodic table, which powerfully and elegantly organizes the elements by increasing atomic number into rows in which the columns share recurring ("periodic") physical and chemical properties. The table contains 118 confirmed elements as of 2021. Although earlier precursors to this ...