Question

describe Lanthanide contraction in 40 to 50 words
​

Answer 1

Answer:

Lanthanoid contraction, also called lanthanide contraction, in chemistry, the steady decrease in the size of the atoms and ions of the rare earth elements with increasing atomic number from lanthanum (atomic number 57) through lutetium (atomic number 71).

Answer 2

Answer:

The regular decrease in the atomic and ionic radii of lanthanoides with increasing atomic number is known as lanthanoid contraction. As we move along the lanthanoid series, the nuclear charge increases by one unit at each successive element. The new electron is added into the same subshell. As a result, the attraction on the electrons by the nucleus increases and this tends to decrease the size. Also as the electron is added to the f- subshell , there is imperfect shielding of electrons by another due to diffused f orbitals. The imperfect shielding is unable to counter balance the effect of increased nuclear charge