Lanthanum and the lanthanides, Chemistry

 

 

LANTHANUM AND THE LANTHANIDES

 

The lanthanides are 14 components following lanthanum in the periodic table, and associated with the filling of the seven orbitals of the 4f shell. The symbol Ln is usually used to denote these elements collectively. Atomic designs are complex with electrons in 4f, 5d and 6s orbitals outside the Xe core. The first three ionization energies are relatively less, leading to electropositive metals with chemistry dominated by the Ln3+ state in solution and in ionic solids. All Ln3 + ions have electron design (4f)n, but the 4f orbitals are highly contracted in size and do not overlap significantly with neighboring ions. Unlike the case with the d orbitals in the transition components, magnetism and spectra associated with 4f orbitals in Ln3+ compounds are same to those found in free gas-phase ions. Chemical bonding and ligand field effects associated with incomplete 4f orbitals are very small and hardly detectable in chemical trends.

 

The chemistry of all Ln3+ ions is therefore same and differentiated only by the gradual contraction in radius associated with increasing nuclear charge. The lanthanide contraction is also important for the transition components of the 5d series. The Ln3+ state is the most stable under normal conditions for all components in the series. Oxides Ln2O3and halides LnX3 are known for all components, as well as an extensive range of oxo salts having mixed and hydrated compounds such as Ln2(SO4)3.3Na2(SO4).12H2O. Ionic radii vary from 104 pm (La3+) to 86 pm (Lu3+) and this relatively bigger size for 3+ ions (cf. Al3+ 53 pm) is associated with correspondingly high coordination numbers in solid compounds. LnF3 elements for earlier elements have nine-coordination, Ln2O3 are seven-coordinate. For later Ln components the decrease in radius goes to changes in structure with reduction in coordination.

 

 

Posted Date: 7/23/2012 7:57:22 AM | Location : United States







Related Discussions:- Lanthanum and the lanthanides, Assignment Help, Ask Question on Lanthanum and the lanthanides, Get Answer, Expert's Help, Lanthanum and the lanthanides Discussions

Write discussion on Lanthanum and the lanthanides
Your posts are moderated
Related Questions
Q.How can we determine Concentrations of Solutions? Ans. The concentration of a solution is the quantitative expression of the amount of solute dissolved in the solution.

A tank containing 100 kg of a 60% brine (60% salt) is filled with a 10% salt solution at the rate of 10 kg/min and 78°F. Solution is removed from the tank at the rate of 15 kg/min.

Liquid phase cracking - Hydrocarbon In that type of cracking, the residual oil or heavy oil is cracked at a high temperature that is from 475 to 530 o C under high pressure fro

Fundamentals of Acids and Bases Bronsted-Lowry theory: A Bronsted acid is a (proton) + donor, whilst a Brønsted base is a proton acceptor. An acid-base reaction involves t

Energy of atomic orbitals in a particular shell is in the order: (1) s (2) s> p > d > f        (3) p (4)  f > d > s >p Ans:  s


what is the symmetry of a star

what is the effect of cement refactory on wear and tear

How many grams of silica gel and plaster of paris and volume of water is needed to have a preparative TLC?