Lesson eLearning

Write the ground‑state electron configuration of yttrium (Y) and indicate whether it belongs to the d‑block or f‑block of the periodic table.

medium 2 marks Class 12 · Chemistry · d- and f-Block Elements
Answer
[Kr]4d¹5s²; d‑block

The correct answer is [Kr]4d¹5s²; d‑block — Yttrium has its outermost electron in a d‑subshell, so it is a d‑block element.

Step-by-step solution

  1. The atomic number of yttrium is 39.
  2. Start filling electrons from the noble gas core [Kr] (Z = 36).
  3. After [Kr], the next available subshells are 5s and then 4d.
  4. Place two electrons in 5s: 5s².
  5. Place the remaining one electron in 4d: 4d¹.
  6. Thus the configuration is [Kr]4d¹5s².
  7. Yttrium has its outermost electron in a d‑subshell, so it is a d‑block element.
Common mistake: Writing the configuration as [Kr]5s²4d¹ (reversing the order) or assigning it to the f‑block.

Concept tested: Electronic configuration and block identification

Published · How this solution was prepared and checked

← All d- and f-Block Elements questions