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Superheavy elements, also known as transactinide elements, transactinides, or super-heavy elements, or superheavies for short, are the chemical elements with atomic number greater than 104. [1] The superheavy elements are those beyond the actinides in the periodic table; the last actinide is lawrencium (atomic number 103).
Heavy metals is a controversial and ambiguous term [2] for metallic elements with relatively high densities, atomic weights, or atomic numbers.The criteria used, and whether metalloids are included, vary depending on the author and context and it has been argued that the term "heavy metal" should be avoided.
Even though half-lives of hundreds or thousands of years would be relatively long for superheavy elements, they are far too short for any such nuclides to exist primordially on Earth. Additionally, instability of nuclei intermediate between primordial actinides ( 232 Th , 235 U , and 238 U ) and the island of stability may inhibit production of ...
The rare-earth elements (REE), also called the rare-earth metals or rare earths, and sometimes the lanthanides or lanthanoids (although scandium and yttrium, which do not belong to this series, are usually included as rare earths), [1] are a set of 17 nearly indistinguishable lustrous silvery-white soft heavy metals. Compounds containing rare ...
In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal currently detectable (i.e. non-dark) matter in the universe is either hydrogen or helium, and astronomers use the word "metals" as convenient shorthand for "all elements except hydrogen and helium".
The abundance of the chemical elements is a measure of the occurrences of the chemical elements relative to all other elements in a given environment. Abundance is measured in one of three ways: by mass fraction (in commercial contexts often called weight fraction), by mole fraction (fraction of atoms by numerical count, or sometimes fraction of molecules in gases), or by volume fraction.
Astatine is the rarest naturally occurring element. [j] The total amount of astatine in the Earth's crust (quoted mass 2.36 × 10 25 grams) [108] is estimated by some to be less than one gram at any given time. [8] Other sources estimate the amount of ephemeral astatine, present on earth at any given moment, to be up to one ounce [109] (about ...
Tellurium and selenium are the heavy elements most depleted by this process. [ 21 ] Tellurium is sometimes found in its native (i.e., elemental) form, but is more often found as the tellurides of gold such as calaverite and krennerite (two different polymorphs of AuTe 2 ), petzite , Ag 3 AuTe 2 , and sylvanite , AgAuTe 4 .