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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.
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.
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 ...
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 ...
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Naturally occurring lanthanum (57 La) is composed of one stable (139 La) and one radioactive (138 La) isotope, with the stable isotope, 139 La, being the most abundant (99.91% natural abundance). There are 39 radioisotopes that have been characterized, with the most stable being 138 La, with a half-life of 1.03×10 11 years; 137 La, with a half ...
He named this village in honor of Edward Tiffin, first governor of Ohio and later a member of the United States Senate who had helped gain statehood for the Ohio Territory in 1803. [11] Tiffin was incorporated by an act of the Ohio Legislature on March 7, 1835. In March 1850, Fort Ball was absorbed by Tiffin. In 1824, with the establishment of ...
Seneca County Airport has one runway designated as runway 6/24. It measures 4000 x 75 ft (1219.2 x 22.9 m) and is paved with asphalt. [1]The airport received $230,000 in 2012 to upgrade its runway and pavement as well as to install guidance signage.