Search results
Results From The WOW.Com Content Network
Rare-earth element. Refined rare-earth oxides are heavy, gritty powders usually brown or black, but can be lighter colors as shown here. The rare-earth elements ( REE ), also called the rare-earth metals or rare earths or, in context, rare-earth oxides, and sometimes the lanthanides (although scandium and yttrium, which do not belong to this ...
The lanthanide ( / ˈlænθənaɪd /) or lanthanoid ( / ˈlænθənɔɪd /) series of chemical elements [ a] comprises at least the 14 metallic chemical elements with atomic numbers 57–70, from lanthanum through ytterbium. In the periodic table, they fill the 4f orbitals. [ 2][ 3][ 4] Lutetium (element 71) is also sometimes considered a ...
Chromium is a chemical element; it has symbol Cr and atomic number 24. It is the first element in group 6. It is a steely-grey, lustrous, hard, and brittle transition metal. [ 7] Chromium metal is valued for its high corrosion resistance and hardness.
Promethium is a chemical element; it has symbol Pm and atomic number 61. All of its isotopes are radioactive; it is extremely rare, with only about 500–600 grams naturally occurring in Earth's crust at any given time. Promethium is one of only two radioactive elements that are followed in the periodic table by elements with stable forms, the ...
Most stable known isotope has half-life of 9.6 seconds. 111: Rg: Roentgenium (28.7) 0: Not traded. Only produced in experiments on a per-atom basis. [73] Most stable known isotope has half-life of 2.1 minutes. 112: Cn: Copernicium (14.0) 0: Not traded. Only tens of atoms have been produced in experiments. [72] Most stable known isotope has half ...
A period 7 element is one of the chemical elements in the seventh row (or period) of the periodic table of the chemical elements.The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behavior of the elements as their atomic number increases: a new row is begun when chemical behavior begins to repeat, meaning that elements with similar behavior fall ...
On the periodic table of the elements it is a p-block element, a member of group 18 and the last member of period 7. Its only known isotope, oganesson-294 , is highly radioactive , with a half-life of 0.7 ms and, as of 2020, [update] only five atoms have been successfully produced. [ 19 ]
Livermorium. Livermorium is a synthetic chemical element; it has symbol Lv and atomic number 116. It is an extremely radioactive element that has only been created in a laboratory setting and has not been observed in nature. The element is named after the Lawrence Livermore National Laboratory in the United States, which collaborated with the ...