Lanthanum and the lanthanides, Chemistry

Assignment Help:

 

 

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.

 

 


Related Discussions:- Lanthanum and the lanthanides

Define the both - direct extrusion and indirect extrusion, Define the both ...

Define the both - Direct extrusion and Indirect extrusion Direct extrusion: Billet is placed in a container and forced through the die by a piston. Indirect extrusion:

Find the resulting moisture content, Question: a) Briefly compare the w...

Question: a) Briefly compare the windrow method v/s the aerated static pile composting b) Explain, with the help of a diagram, the role of aeration in turned windrow compos

IInorganic chemistry, Why magnesium does not impart any colour to Bunsen fl...

Why magnesium does not impart any colour to Bunsen flame while calcium does

DSC., How to get Energy vs Temperature curve from DSC data

How to get Energy vs Temperature curve from DSC data

Hookes law simulation, Hookes Law simulation Using a horizontal and a v...

Hookes Law simulation Using a horizontal and a vertical spring that this applet simulates Hooke's law and easy harmonic motion. As discussed previously, the amount of stretchin

Explain physical changes of food deterioration, Physical Changes Physi...

Physical Changes Physical changes are caused by mishandling of foods during harvesting, processing and distribution; these changes lead to reduced shelf life of foods. Crushin

Electrolysis, How to know prefrential discharge for ions

How to know prefrential discharge for ions

Organic, Write essey on organic quantitative analysis

Write essey on organic quantitative analysis

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd