Question

Explain the meaning of transition series. 

OR 

Explain in brief, four series of transition elements.

Answer 1

i. d-block elements are also known as transition elements. The long form of periodic table contains four series of transition elements, known as transition series.

ii. Four transition series are 3d, 4d, 5d and 6d series wherein orbitals of (n - 1)^th main shell gets filled.

a. The 3d series contains the elements from Sc (Z = 21) to Zn (Z = 30) belonging to the 4^th period.

b. The 4d series contains the elements from Y (Z = 39) to Cd (Z = 48) belonging to the 5^th period.

c. The 5d series begins with La (Z = 57) and contains elements from Hf (Z = 72) to Hg (Z = 80) belonging to the 6^th period.

d. The 6d series begins with Ac (Z = 89) and contains elements from Rf (Z = 104) to Uub (Z = 112) belonging to the 7^th period.