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Lanthanum is a chemical element with the symbol La and the atomic number 57. It is a soft , ductile , silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table , of which lanthanum is the first and the prototype.
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.
The term rare-earth element or rare-earth metal is often used to include the stable group 3 elements Sc, Y, and Lu in addition to the 4f elements. [8] All lanthanide elements form trivalent cations, Ln 3+, whose chemistry is largely determined by the ionic radius, which decreases steadily from lanthanum (La) to lutetium (Lu).
The CuTi 2 structure of the lanthanum, cerium and praseodymium diiodides along with HP-NdI 2 contain 4 4 nets of metal and iodine atoms with short metal-metal bonds (393-386 La-Pr). [ 10 ] these compounds should be considered to be two-dimensional metals (two-dimensional in the same way that graphite is).
Polane (polonium hydride) is a more covalent compound than most metal hydrides because polonium straddles the border between metal and metalloid and has some nonmetallic properties: it is intermediate between a hydrogen halide like hydrogen chloride (HCl) and a metal hydride like stannane (SnH 4).
This is a list of prices of chemical elements. Listed here are mainly average market prices for bulk trade of commodities. Data on elements' abundance in Earth's crust is added for comparison. As of 2020, the most expensive non-synthetic element by both mass and volume is rhodium.
This is a similar pattern to those of the early transition metal groups, where the lightest element is distinct from the very similar next two. All the group 3 elements are rather soft, silvery-white metals, although their hardness increases with atomic number.
Praseodymium is a chemical element; it has symbol Pr and the atomic number 59. It is the third member of the lanthanide series and is considered one of the rare-earth metals. It is a soft, silvery, malleable and ductile metal, valued for its magnetic, electrical, chemical, and optical