Question

What are lanthanoids (or lanthanides)? 

OR 

What is the lanthanoid series?

Answer 1

• Lanthanoids or Lanthanoid series or Lanthanones :  The series of fourteen elements from ₅₈Ce to ₇₁Lu in which a differentiating electron enters 4f subshell and follows lanthanum is called lanthanoid series and the elements are called lanthanoids.
• They have general electronic configuration, [Xe] 4f^1-14 ,5d^0-1, 6s².
• They follow Lanthanum (Z = 57) in 3d-series.