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The lanthanide contraction is the greater-than-expected decrease in atomic radii and ionic radii of the elements in the lanthanide series, from left to right. It is caused by the poor shielding effect of nuclear charge by the 4f electrons along with the expected periodic trend of increasing electronegativity and nuclear charge on moving from left to right.
All of the lanthanides form Ln 2 Q 3 (Q= S, Se, Te). [18] The sesquisulfides can be produced by reaction of the elements or (with the exception of Eu 2 S 3) sulfidizing the oxide (Ln 2 O 3) with H 2 S. [18] The sesquisulfides, Ln 2 S 3 generally lose sulfur when heated and can form a range of compositions between Ln 2 S 3 and Ln 3 S 4.
This is the energy per mole necessary to remove electrons from gaseous atoms or atomic ions. The first molar ionization energy applies to the neutral atoms. The second, third, etc., molar ionization energy applies to the further removal of an electron from a singly, doubly, etc., charged ion.
The adiabatic ionization energy of a molecule is the minimum amount of energy required to remove an electron from a neutral molecule, i.e. the difference between the energy of the vibrational ground state of the neutral species (v" = 0 level) and that of the positive ion (v' = 0). The specific equilibrium geometry of each species does not ...
The principal sources of rare-earth elements are the minerals bastnäsite (RCO 3 F, where R is a mixture of rare-earth elements), monazite (XPO 4, where X is a mixture of rare-earth elements and sometimes thorium), and loparite ((Ce,Na,Ca)(Ti,Nb)O 3), and the lateritic ion-adsorption clays.
Ionic potential is the ratio of the electrical charge (z) to the radius (r) of an ion. [1]= = As such, this ratio is a measure of the charge density at the surface of the ion; usually the denser the charge, the stronger the bond formed by the ion with ions of opposite charge.
The electrostatic energy of the ion at site r i then is the product of its charge with the potential acting at its site E e l , i = z i e V i = e 2 4 π ε 0 r 0 z i M i . {\displaystyle E_{el,i}=z_{i}eV_{i}={\frac {e^{2}}{4\pi \varepsilon _{0}r_{0}}}z_{i}M_{i}.}
In 1953, Brillouin derived a general equation [10] stating that the changing of an information bit value requires at least kT ln(2) energy. This is the same energy as the work Leo Szilard 's engine produces in the idealistic case, which in turn equals the same quantity found by Landauer .