Physical and Chemical Properties of Lanthanides
The lanthanides are the 15 metallic elements that have atomic numbers ranging from 57 to 71.
They are often referred to as rare earth metals since their abundance in the Earth’s crust is very
low. The physical and chemical properties of lanthanides are briefly discussed in this article.
Physical Properties :-
The lanthanides are soft and shiny metals (as is the case with the alkali metals). However, not
all lanthanides are highly reactive. Their reactivities depend on several factors including their
basicity. When contaminated with other metals or non-metals, these elements can corrode or
become brittle. Generally, the lanthanides form trivalent compounds. However, they can also
form divalent or tetravalent compounds. They also hold magnetic properties. The lanthanides
have high melting points and high boiling points.
Chemical Properties :-
The chemical reactivities of the lanthanides are similar but are much higher than that of the
transition metals (d-block elements). They are readily tarnished by oxygen, forming oxides with
the general formula M 2 O 3 . the halides of these elements can be obtained by heating them with a
halogen, or by heating their oxides with ammonium halides. These elements also exhibit various
oxidation states but the most commonly exhibited oxidation state is +3.
The atomic or ionic radii of the lanthanides (or the +3 charged lanthanide cations) decrease in a
steady fashion along the period (from left to right). This is caused by the increase in the effective
nuclear charge and the filling of the (n-2)f orbital. This steady decrease in the atomic/ionic radii
of the lanthanides is commonly referred to as lanthanide contraction.
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