### Related Formula textAzimuthal Quantum Number: l=1 implies textp-orbital, quad l=2 implies textd-orbital$\text{Azimuthal Quantum Number: } l=1 \implies \text{p-orbital}, \quad l=2 \implies \text{d-orbital}$ ### Core Logic The ground-state electronic configuration of Chromium (Z=24$Z=24$) is anomalous due to half-filled stability: Cr: 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 3d^5 \, 4s^1$Cr: 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 3d^5 \, 4s^1$ Now count the electrons in specific subshells: - For l = 1$l = 1$ (p-electrons): present in 2p^6$2p^6$ and 3p^6 implies 6 + 6 = 12$3p^6 \implies 6 + 6 = 12$ electrons. - For l = 2$l = 2$ (d-electrons): present in 3d^5 implies 5$3d^5 \implies 5$ electrons. Thus, the counts are **12 and 5** respectively. ### Pattern Recognition Always remember the 3d^5 4s^1$3d^5 4s^1$ exception for Chromium (Z=24$Z=24$) and 3d^10 4s^1$3d^{10} 4s^1$ for Copper (Z=29$Z=29$). Forgetting the half-filled d-subshell exception will lead to the wrong answer (12 and 4). ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Chemistry: Structure of Atom