Question

What is lanthanide contraction and write its result also

Answer 1

Lanthanide contraction is the greater than expected decrease in the ionic radii of the elements in the lanthanide series from atomic number 57 to 71. This results in smaller than otherwise expected ionic radii for the subsequent elements. This is theresult of the shielding effect.

Answer 2

Lanthanide Contraction is defined as the steady decrease in the size of lanthanide ions (M 3+) with the increase in atomic no. in lanthanide series is called lanthanide contraction. As we move down the group from left to right in a lanthanide series, the atomic no. increases and for every proton in the nucleus the extra electron goes to 4f orbital. The 4f orbital is too diffused to shield the nucleus effectively, thus there is a gradual increase in the effective nuclear charge experienced by the outer electrons. Consequently , the attraction of the nucleus for the electrons in the outermost shell increases with the increase of atomic number, thus size decreases.