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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 electronic configuration of most neutral gas-phase lanthanide atoms is [Xe]6s 2 4f n, where n is 56 less than the atomic number Z. Exceptions are La, Ce, Gd, and Lu, which have 4f n−1 5d 1 (though even then 4f n is a low-lying excited state for La, Ce, and Gd; for Lu, the 4f shell is already full, and the fifteenth electron has no choice ...
57 La 2-1 - 58 Ce 2 1 1 - 59 Pr 2 3-- 60 Nd 2 4-- 61 Pm 2 5-- 62 Sm 2 6-- 63 Eu 2 7-- 64 Gd 2 7 1 ... Note that these electron configurations are given for neutral ...
Here [Ne] refers to the core electrons which are the same as for the element neon (Ne), the last noble gas before phosphorus in the periodic table. The valence electrons (here 3s 2 3p 3) are written explicitly for all atoms. Electron configurations of elements beyond hassium (element 108) have never been measured; predictions are used below.
A period 6 element is one of the chemical elements in the sixth row (or period) of the periodic table of the chemical elements, including the lanthanides.The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements ...
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In 2001, an 18-year-old committed to a Texas boot camp operated by one of Slattery’s previous companies, Correctional Services Corp., came down with pneumonia and pleaded to see a doctor as he struggled to breathe.