Question

Similarity between $Nb$ and $Ta$ is because they:

• A. are transition metals
• B. belong to same group of periodic table
• C. have the same mineral source
• D. have almost same ionic and covalent radii

Answer 1

The correct option is D have almost same ionic and covalent radii

The similarity between $Nb$ and $Ta$ is because they have almost same ionic and covalent radii.
Due to Lanthanide contraction, $Nb$ and $Ta$ show similar atomic and ionic size.
The elements which follow the lanthanoids in the third transition series are known as post lanthanoids. Due to lanthanoid contraction, the atomic radii of the elements which follow lanthanum ($Hf,Ta,W$ etc) are similar to that of the elements of the previous period. $Nb$ and $Ta$ have almost identical sizes. They have a similar number of valence electrons and similar properties. They are called chemical twins.