Consider the ground state of chromium atom $(Z=24)$. How many electrons are with Azimuthal quantum number $l=1$ and $l=2$ respectively ?
Solution
<p>The ground state electron configuration of chromium (Cr, $ Z = 24 $) is:</p>
<p>$\text{Cr: } [\text{Ar}]\,3d^5\,4s^1$</p>
<p>Let's break down the configuration:</p>
<p>The noble gas core $[\text{Ar}]$ represents:</p>
<p><p>$1s^2$ (with $l=0$)</p></p>
<p><p>$2s^2$ (with $l=0$)</p></p>
<p><p>$2p^6$ (with $l=1$)</p></p>
<p><p>$3s^2$ (with $l=0$)</p></p>
<p><p>$3p^6$ (with $l=1$)</p></p>
<p>Electrons with azimuthal quantum number $l = 1$ are found in $p$ orbitals:</p>
<p><p>$2p^6$: 6 electrons</p></p>
<p><p>$3p^6$: 6 electrons</p></p>
<p><p>Total $p$-electrons: $6 + 6 = 12$.</p></p>
<p>Electrons with azimuthal quantum number $l = 2$ are found in $d$ orbitals:</p>
<p>$3d^5$: 5 electrons</p>
<p>Thus, there are 12 electrons with $l = 1$ and 5 electrons with $l = 2$.</p>
<p>The correct option is Option B.</p>
About this question
Subject: Chemistry · Chapter: Atomic Structure · Topic: Bohr's Model
This question is part of PrepWiser's free JEE Main question bank. 122 more solved questions on Atomic Structure are available — start with the harder ones if your accuracy is >70%.