Question

why niobium and tantalam have almost same radiys​

Answer 1

Answer:

Due to lanthanide contraction. As the shielding of 4f orbitals are not particularly effective though there is increasing nuclear charge the elements immediately following the lanthanide have atomic radii similar. .

Answer 2

Answer:

Due to Ianthanide contraction. As the shielding of 4f orbitals are not particularly effective thought there is increasing nuclear charge the elements immediately following the lanthanide have atomic radii similar.

Explanation:

#Hope it help.