Question

use the following electron configuration of europium 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶4d¹⁰4f⁷5s²5p⁶6s². how many sublevels are occupied?

Explanation:

Step1: Identify sublevels in electron config

The electron - configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{10}4s^{2}4p^{6}4d^{10}4f^{7}5s^{2}5p^{6}6s^{2}$. The sublevels are $1s$, $2s$, $2p$, $3s$, $3p$, $3d$, $4s$, $4p$, $4d$, $4f$, $5s$, $5p$, $6s$.

Step2: Count occupied sublevels

Counting these sublevels, we find there are 13 occupied sublevels.

Answer:

d. 13